WEBVTT 00:01.440 --> 00:02.000 Prof: Good morning. 00:02.000 --> 00:03.670 We can start. 00:03.670 --> 00:07.710 Today we'll be discussing poliomyelitis, 00:07.706 --> 00:09.876 or polio for short. 00:09.880 --> 00:14.000 And you may be wondering why we've included it at this point, 00:13.995 --> 00:16.185 late in the day in our course. 00:16.190 --> 00:20.740 And that's because a number of you have been saying that you'd 00:20.744 --> 00:24.934 like to have the course come right up to date and today's 00:24.925 --> 00:29.185 newspapers, and the way I want to deal with 00:29.188 --> 00:33.418 polio, I hope, is in light of that 00:33.415 --> 00:34.555 request. 00:34.560 --> 00:37.800 In other words, we're going to be dealing with 00:37.796 --> 00:42.976 polio at this very moment; and in particular with problems 00:42.981 --> 00:47.481 of vaccination, that very major public health 00:47.482 --> 00:48.712 strategy. 00:48.710 --> 00:53.930 The subject will really be the problems facing the Global Polio 00:53.927 --> 00:58.467 Eradication Initiative which, just to remind you, 00:58.469 --> 01:03.629 is the largest public health campaign ever launched. 01:03.630 --> 01:09.080 It predicted global eradication by 2000. 01:09.078 --> 01:14.948 And when it began in 1988 it used as its model the 01:14.947 --> 01:20.607 eradication of smallpox, as you know pioneered long ago 01:20.610 --> 01:24.260 by Edward Jenner, and actually reaching 01:24.260 --> 01:29.280 successful conclusion in 1980 when the World Health 01:29.284 --> 01:34.714 Organization certified that the world globe was free of 01:34.712 --> 01:38.132 naturally occurring smallpox. 01:38.129 --> 01:42.939 There seemed to be a number of reasons that smallpox could be 01:42.944 --> 01:44.634 taken as the model. 01:44.629 --> 01:49.219 This was the first disease, and still the only one, 01:49.215 --> 01:52.235 major disease, actually eradicated 01:52.242 --> 01:58.022 intentionally by human beings, by a public health campaign. 01:58.019 --> 02:03.909 It was thought that polio had a number of features that made it 02:03.912 --> 02:08.572 a similarly good candidate, just like smallpox. 02:08.568 --> 02:11.038 It was a disease, like smallpox, 02:11.036 --> 02:13.976 that possessed no animal reservoir. 02:13.979 --> 02:18.159 So, if you got rid of it in the human population, 02:18.163 --> 02:23.403 it wouldn't again jump species and recur through transmission 02:23.395 --> 02:25.745 from animals to humans. 02:25.750 --> 02:30.460 It was also a viral disease, and the pathogen has no 02:30.461 --> 02:32.681 complicated lifecycle. 02:32.680 --> 02:35.990 It's at the other end of the spectrum from, 02:35.991 --> 02:38.991 for example, the malarial plasmodia. 02:38.990 --> 02:44.850 The acquired resistance is robust, produced by the body 02:44.848 --> 02:46.148 naturally. 02:46.150 --> 02:52.560 That was true of polio, as it is of smallpox. 02:52.560 --> 02:58.780 And it was the case that just as in the example of smallpox, 02:58.782 --> 03:05.322 so too with polio there seemed to be a very robust and powerful 03:05.319 --> 03:08.359 tool; that is, two vaccines, 03:08.358 --> 03:13.768 one injected--we'll come back to that--and the other oral, 03:13.770 --> 03:15.860 the polio vaccines. 03:15.860 --> 03:20.280 But as we speak, the global eradication program 03:20.278 --> 03:25.178 has run into serious and unexpected difficulties. 03:25.180 --> 03:28.880 After it was originally launched in 1988, 03:28.878 --> 03:33.408 it went from success to success, and seemed to be poised 03:33.408 --> 03:38.648 for successful eradication, if perhaps not by its original 03:38.645 --> 03:43.195 timetable of 2000, well then perhaps just a little 03:43.198 --> 03:44.158 bit later. 03:44.160 --> 03:49.790 But in 2003 major difficulties overtook the campaign-- 03:49.788 --> 03:55.038 and we'll come back to those--and now the campaign is a 03:55.041 --> 04:00.631 decade behind schedule, and the elusive goal of global 04:00.633 --> 04:04.213 eradication seems to be receding, 04:04.210 --> 04:06.970 rather than becoming closer. 04:06.968 --> 04:11.928 It stalled particularly in four endemic countries-- 04:11.930 --> 04:16.700 India, Afghanistan, Pakistan and Nigeria-- 04:16.699 --> 04:21.279 and even spread, particularly from Nigeria, 04:21.279 --> 04:24.209 to an array of other countries. 04:24.209 --> 04:29.519 So, the question is whether this stalling is temporary and 04:29.519 --> 04:33.989 for contingent reasons likely to be overcome, 04:33.990 --> 04:39.540 or was eradication on the smallpox model a mirage from the 04:39.540 --> 04:40.320 start? 04:40.319 --> 04:45.689 And this can be personified in a major debate between two 04:45.690 --> 04:50.390 leading figures in international public health. 04:50.389 --> 04:56.039 One is Bruce Aylward, who's the director general of 04:56.036 --> 05:01.566 the Global Public Polio Eradication Initiative. 05:01.569 --> 05:05.899 He's a great optimist, and says that the problem is 05:05.896 --> 05:11.346 simply a matter of pressing harder when difficulties emerge, 05:11.350 --> 05:16.820 and he envisages eradication in short order. 05:16.819 --> 05:22.429 Then there's D.A. Henderson, and he was the former director 05:22.430 --> 05:27.460 of the successful Smallpox Eradication Program, 05:27.459 --> 05:32.159 and he was the director of polio eradication in the region 05:32.163 --> 05:33.653 of the Americas. 05:33.649 --> 05:37.879 Originally he was a very enthusiastic eradicator, 05:37.879 --> 05:43.079 but now he's come round to the view instead that eradication 05:43.077 --> 05:46.777 was a mistaken concept from the start; 05:46.779 --> 05:52.049 that it will simply never work with polio, which is totally 05:52.053 --> 05:53.693 unlike smallpox. 05:53.690 --> 05:56.000 This morning, fortunately, 05:55.995 --> 06:00.975 we don't need to make a decision, and hopefully Aylward 06:00.978 --> 06:03.098 will be successful. 06:03.100 --> 06:07.810 But I do think we need to understand how difficult the 06:07.812 --> 06:12.792 eradication of a disease actually is, and to remember how 06:12.790 --> 06:16.170 exceptional smallpox is as a case. 06:16.170 --> 06:20.440 Polio reminds us that smallpox was an outlier, 06:20.444 --> 06:22.634 rather than the norm. 06:22.629 --> 06:25.269 Furthermore, the polio problem is 06:25.271 --> 06:30.231 intellectually interesting, and we ought to understand it 06:30.230 --> 06:34.760 in order to comprehend tomorrow's press reports on why 06:34.764 --> 06:38.104 eradication perhaps didn't succeed, 06:38.100 --> 06:40.150 if that's the outcome. 06:40.149 --> 06:43.679 I don't want to make a prediction because I'm mindful 06:43.677 --> 06:49.137 of that great sage, Yogi Berra, who had a saying, 06:49.144 --> 06:55.414 "never make a prediction, especially if it's about the 06:55.410 --> 06:56.350 future." 06:56.350 --> 06:59.410 In any case, we don't know whether polio 06:59.411 --> 07:01.611 will be eradicated or not. 07:01.610 --> 07:06.120 I tend to be a skeptic, but I really hope I'm wrong. 07:06.120 --> 07:10.640 The poliovirus has three types, polio 1, 07:10.639 --> 07:17.539 2 and 3, and it enters the body via the mouth, 07:17.540 --> 07:22.940 perhaps through contaminated food or water, 07:22.939 --> 07:29.119 or in unsanitary conditions with direct contact with stools, 07:29.120 --> 07:34.000 or with the secretions from the throat of a patient. 07:34.000 --> 07:38.720 The virus then settles in the intestinal tract and it 07:38.723 --> 07:40.453 multiplies there. 07:40.449 --> 07:45.169 And that's a picture of the poliovirus. 07:45.170 --> 07:49.480 After an incubation period of one to five days, 07:49.483 --> 07:55.113 it then settles in lymphatic tissue, along the intestines and 07:55.112 --> 07:57.272 in the lymph nodes. 07:57.269 --> 08:01.659 Now, normally the virus does no appreciable harm in the 08:01.658 --> 08:05.148 digestive tract, producing nothing more than 08:05.153 --> 08:07.513 some swollen lymph nodes. 08:07.509 --> 08:11.989 And apart from that, the infection can be totally 08:11.990 --> 08:13.390 asymptomatic. 08:13.389 --> 08:18.059 In some cases it leads to minor symptoms-- 08:18.060 --> 08:22.300 these are brief--such as a mild fever, 08:22.300 --> 08:26.350 and other symptoms that would make you think of seasonal 08:26.346 --> 08:31.066 influenza: headache, nausea, vomiting. 08:31.069 --> 08:38.059 Then the patient recovers with nothing more occurring. 08:38.058 --> 08:42.668 And that's true then of the vast majority of cases that end 08:42.667 --> 08:43.777 in that way. 08:43.779 --> 08:49.209 And indeed, in the historical literature, this was termed 08:49.206 --> 08:53.466 abortive poliomyelitis, because the infection 08:53.470 --> 08:55.990 progressed no further. 08:55.990 --> 09:01.230 But in about one percent or so of cases, 09:01.230 --> 09:05.020 there's something much more serious that occurs, 09:05.019 --> 09:09.029 which is the involvement of the central nervous system, 09:09.028 --> 09:13.758 and that's where the disease, if it becomes so established, 09:13.759 --> 09:16.769 does its serious damage. 09:16.769 --> 09:21.429 It destroys nerves, especially in the spinal cord 09:21.427 --> 09:22.977 and the brain. 09:22.980 --> 09:30.240 Let me show you a rather--a schematic--rather scary picture 09:30.238 --> 09:35.618 of the poliovirus attacking a nerve cell. 09:35.620 --> 09:41.130 When this occurs, the results are severe pain, 09:41.133 --> 09:46.773 weakness in the muscles, and then paralysis; 09:46.769 --> 09:51.759 and the paralysis can be one leg, both legs, 09:51.755 --> 09:56.275 the arms, and the respiratory system. 09:56.279 --> 10:00.459 The paralysis also is normally irreversible, 10:00.460 --> 10:06.000 and often leads to very severe deformity or maiming of the 10:06.001 --> 10:07.851 affected limbs. 10:07.850 --> 10:12.700 If the muscles involved are those of the respiratory system, 10:12.701 --> 10:16.981 the result can be respiratory paralysis and death. 10:16.980 --> 10:24.740 Let me show you some images of the work of poliomyelitis. 10:24.740 --> 10:29.990 This is a picture from the 1950s of a child in 10:29.988 --> 10:34.068 rehabilitation, with paralyzed legs, 10:34.070 --> 10:36.870 braces and calipers. 10:36.870 --> 10:43.520 Or we can see this is a poster of the campaign against 10:43.520 --> 10:45.530 poliomyelitis. 10:45.529 --> 10:51.379 Or this is the iron lung that was used to save the lives of 10:51.379 --> 10:56.419 those who had respiratory paralysis, and we can see 10:56.423 --> 11:00.663 another iron lung with a child inside. 11:00.658 --> 11:05.238 And a terrible picture, that was all too common in the 11:05.240 --> 11:09.910 thirties, forties and fifties, which is a whole ward of 11:09.905 --> 11:12.235 children in iron lungs. 11:12.240 --> 11:17.890 So, this really was a terrible and cataclysmic disease in its 11:17.890 --> 11:19.210 severe form. 11:19.210 --> 11:20.910 What about the history? 11:20.908 --> 11:28.578 Poliomyelitis used to be called "infantile paralysis." 11:28.580 --> 11:32.460 Until the 1890s, it was regarded as a minor 11:32.458 --> 11:35.598 medical and public health issue. 11:35.600 --> 11:40.450 It really exploded onto the world as a major public health 11:40.452 --> 11:43.862 and medical problem only in the 1890s. 11:43.860 --> 11:48.330 That's not to say that polio was an emerging disease of the 11:48.326 --> 11:50.886 1890s, but I'm going to say that 11:50.889 --> 11:55.009 something new happened that transformed awareness of the 11:55.005 --> 11:55.825 disease. 11:55.830 --> 12:01.460 It was thought then originally to be an exotic and unimportant 12:01.456 --> 12:04.866 endemic disease of early childhood. 12:04.870 --> 12:10.260 But something happened in the 1890s, and polio began to appear 12:10.260 --> 12:14.500 as something different, especially in the Western 12:14.503 --> 12:16.363 industrial world. 12:16.360 --> 12:21.550 It began to appear as a virulent epidemic disease. 12:21.548 --> 12:25.598 It struck older groups of people, adolescents and 12:25.604 --> 12:30.004 grownups, as well as infants, and in its wake it left 12:29.996 --> 12:33.626 clusters of dead and paralyzed victims. 12:33.629 --> 12:38.889 The first substantial epidemics ever recorded struck 12:38.894 --> 12:42.614 Scandinavia, Sweden, in the 1890s; 12:42.610 --> 12:46.390 in this country Vermont, in 1894; 12:46.389 --> 12:51.619 Scandinavia again in 1905; New York in 1907; 12:51.620 --> 12:57.180 Vienna in 1908; and the northeast of the United 12:57.181 --> 13:01.141 States in a devastating epidemic in 1916. 13:01.139 --> 13:05.879 After that, epidemics of polio became a recurring and 13:05.883 --> 13:11.633 terrifying feature of the warm months of the industrial West. 13:11.629 --> 13:13.759 In the U.S., for example, 13:13.759 --> 13:17.489 polio struck with ever increasing fury, 13:17.490 --> 13:24.250 reaching a peak of ferocity in the years 1950 to 1954, 13:24.250 --> 13:29.770 and by that time it had taken over from tuberculosis as the 13:29.769 --> 13:32.909 most feared disease of the era. 13:32.909 --> 13:35.169 Well, what happened? 13:35.168 --> 13:38.038 And here I think we ought to be careful. 13:38.038 --> 13:42.238 Let's avoid an error that misled epidemiologists and 13:42.244 --> 13:46.864 public health officials, at least until World War II, 13:46.860 --> 13:52.070 and that sometimes has misled medical historians since then. 13:52.070 --> 13:57.590 The mistake was to think that polio was in some simple way a 13:57.592 --> 14:01.532 disease of the affluent industrial nations, 14:01.525 --> 14:06.015 of the clean and the prosperous within them. 14:06.019 --> 14:11.609 In reality, poliovirus, as we know, is transmitted by 14:11.610 --> 14:17.090 the oral-fecal route, and it was ubiquitous in human 14:17.091 --> 14:20.641 populations across the globe. 14:20.639 --> 14:26.269 But hygienic advances transformed its epidemiology. 14:26.269 --> 14:30.859 The sanitary bulwarks of the modern industrial state 14:30.863 --> 14:35.553 prevented children from encountering the virus during 14:35.547 --> 14:41.547 infancy and early childhood, and therefore they failed to 14:41.548 --> 14:46.198 build an acquired immunity to the disease. 14:46.200 --> 14:49.530 As a result, the numbers of susceptible 14:49.528 --> 14:53.468 people in populations began to accumulate, 14:53.470 --> 15:00.460 and that provided the basis for periodic large-scale epidemics 15:00.461 --> 15:03.671 that struck at later ages. 15:03.668 --> 15:08.758 There was a distinguished Yale epidemiologist named John Paul 15:08.758 --> 15:13.588 who was very active in the middle decades of the twentieth 15:13.592 --> 15:17.242 century in dealing with poliomyelitis, 15:17.240 --> 15:22.450 and he argued that the disease should no longer be called 15:22.445 --> 15:24.485 infantile paralysis. 15:24.490 --> 15:28.210 Under the circumstances, he said, that term should be 15:28.210 --> 15:31.930 replaced with the phrase "modern polio." 15:31.928 --> 15:34.678 And modern polio, as he called it, 15:34.676 --> 15:38.666 demonstrated a strong predilection for relatively 15:38.669 --> 15:43.109 prosperous older children, adolescents and adults, 15:43.105 --> 15:47.295 and it did so in the economically advanced nations of 15:47.298 --> 15:50.998 the world: Northern Europe, North America, 15:51.000 --> 15:53.060 Australia, New Zealand. 15:53.058 --> 15:57.378 Polio, in this sense, what John Paul called modern 15:57.384 --> 16:00.394 polio, seemed to be--if we could toy 16:00.388 --> 16:04.498 with a phrase that's all too familiar to you by now-- 16:04.500 --> 16:09.580 it seemed to be a kind of social disease in reverse. 16:09.580 --> 16:15.130 That is, it seemed to cause epidemics among the clean, 16:15.125 --> 16:18.365 the wealthy and the suburban. 16:18.370 --> 16:23.580 And, so, polio became a highly visible epidemic disease that 16:23.581 --> 16:26.661 terrified, because it was so visible, 16:26.664 --> 16:30.984 because there was no cure, and because everyone seemed to 16:30.980 --> 16:34.520 be vulnerable, while the disease itself left 16:34.515 --> 16:37.425 in its wake, after each visitation, 16:37.431 --> 16:41.561 thousands of people who were maimed and crippled, 16:41.559 --> 16:45.059 as well as the dead. 16:45.058 --> 16:48.828 But the reality was a little different. 16:48.830 --> 16:54.150 Although epidemic modern poliomyelitis increased the pace 16:54.147 --> 16:57.847 of its ravages in the Western world, 16:57.850 --> 17:03.290 proof soon emerged that polio also imposed an unnoticed but 17:03.294 --> 17:08.374 equally heavy tribute of suffering in the resource-poor 17:08.365 --> 17:10.145 tropical world. 17:10.150 --> 17:14.650 In other words, this was an illusion that it 17:14.653 --> 17:19.893 was only afflicting the industrial, clean world. 17:19.890 --> 17:23.150 This caused enormous surprise. 17:23.150 --> 17:28.180 The prevailing dogma was that poliomyelitis was an affliction 17:28.176 --> 17:32.946 of modernity and sanitation, and was of negligible concern 17:32.952 --> 17:35.302 in the developing world. 17:35.299 --> 17:38.519 But World War II caused a shock. 17:38.519 --> 17:43.669 Suddenly there was the experience of non-immune U.S., 17:43.670 --> 17:48.890 British, Australian troops, stationed in places like Egypt 17:48.891 --> 17:52.511 or the Pacific, and there, against all 17:52.513 --> 17:57.173 expectations, significant numbers of them 17:57.165 --> 18:00.345 contracted poliomyelitis. 18:00.348 --> 18:04.898 And then this disturbing finding was confirmed by 18:04.903 --> 18:08.893 evidence from serological examinations, 18:08.890 --> 18:14.690 from rectal swabs, from laboratory analysis of the 18:14.689 --> 18:19.659 microbial bounty in Third-World sewers, 18:19.660 --> 18:26.490 and by lameness surveys--that is actually counting people who 18:26.492 --> 18:33.222 are afflicted by paralysis-- in places like India. 18:33.220 --> 18:37.870 And the evidence confirmed that paralytic poliomyelitis in the 18:37.867 --> 18:42.437 tropics was actually greater than in the developed world, 18:42.440 --> 18:46.720 at its height, but that it was unnoticed. 18:46.720 --> 18:48.470 Why was it not noticed? 18:48.470 --> 18:52.940 It was not noticed, in part, because physicians and 18:52.936 --> 18:58.206 public health officials had long taught not to expect it; 18:58.210 --> 19:01.240 everyone closed their eyes. 19:01.240 --> 19:05.110 It was also true because the impoverished children of the 19:05.112 --> 19:09.262 tropical world had so little access to medical care that they 19:09.259 --> 19:13.399 simply weren't seen; they were invisible. 19:13.400 --> 19:18.440 Because the illnesses of the poor were regarded as 19:18.442 --> 19:22.872 unremarkable, and because the poor themselves 19:22.865 --> 19:28.145 fatalistically expected that their children would suffer and 19:28.145 --> 19:31.275 die in disproportionate numbers. 19:31.278 --> 19:37.758 Meanwhile, maimed and paralyzed children grew up in the Tropical 19:37.759 --> 19:43.009 world to join the ranks of beggars in the streets of 19:43.006 --> 19:45.986 Jakarta, Cairo and Lagos. 19:45.990 --> 19:51.140 Well, the poliovirus was discovered in 1908 by Karl 19:51.143 --> 19:55.203 Landsteiner-- who's on your handout--but 19:55.202 --> 20:01.102 thereafter the natural history of the disease remains shrouded 20:01.096 --> 20:02.446 in mystery. 20:02.450 --> 20:06.440 Still in 1950, the mode of transmission and 20:06.443 --> 20:12.343 the portal of entry of the virus into the body were unknown; 20:12.338 --> 20:17.748 as was the issue of whether poliovirus existed in a single 20:17.749 --> 20:21.829 strain, or serotype, or in multiple ones. 20:21.829 --> 20:24.789 Was there one type or many? 20:24.788 --> 20:29.208 Similarly, the immune mechanisms of the body were not 20:29.212 --> 20:30.322 understood. 20:30.318 --> 20:34.788 And, in fact, a critical mistake was made 20:34.786 --> 20:37.876 that-- and this mistake misled the 20:37.884 --> 20:42.934 public health community, researchers and medical science 20:42.932 --> 20:47.372 for a long period, from the 1920s or so, 20:47.365 --> 20:52.515 down to the 1950s-- and this was to assume that the 20:52.516 --> 20:57.786 course of the disease in human beings was the same as that in 20:57.791 --> 20:58.761 monkeys. 20:58.759 --> 21:03.019 In other words, there was an extrapolation from 21:03.016 --> 21:06.066 the laboratory to human beings. 21:06.068 --> 21:09.178 And this mistake had a number of corollaries. 21:09.180 --> 21:14.640 It meant that it was assumed that the portal of entry of the 21:14.635 --> 21:18.695 virus was the nose, rather than the digestive 21:18.704 --> 21:19.634 tract. 21:19.630 --> 21:24.960 It was assumed that the disease primarily attacked the central 21:24.957 --> 21:29.307 nervous system, and that the virus made its way 21:29.311 --> 21:33.711 from the nose to the spinal cord and the brain, 21:33.710 --> 21:37.290 via the nervous system. 21:37.288 --> 21:41.578 Well in terms of public health, and the possibility of vaccine 21:41.584 --> 21:45.854 development, these conclusions were entirely 21:45.848 --> 21:52.118 counterproductive, because they led to a corollary. 21:52.118 --> 21:55.868 The corollary was that since the disease spread via the 21:55.868 --> 21:59.268 nervous system, rather than the bloodstream, 21:59.265 --> 22:03.935 there was no opportunity for antibodies to mount a defense, 22:03.940 --> 22:10.080 and therefore no possibility for developing a vaccine. 22:10.078 --> 22:16.088 Then we have an enormous campaign of research and public 22:16.087 --> 22:23.077 health against this increasingly feared and terrible disease, 22:23.078 --> 22:29.378 and this was with the National Foundation of Infantile 22:29.383 --> 22:34.783 Paralysis, and it spawned the March of 22:34.782 --> 22:39.552 Dimes Campaign, which collected enormous 22:39.545 --> 22:43.335 amounts of money devoted to research, 22:43.338 --> 22:47.618 and also to the care and rehabilitation of the victims of 22:47.616 --> 22:48.836 poliomyelitis. 22:48.838 --> 22:53.478 Let me just show you some images of the collecting of 22:53.480 --> 22:58.390 funds in the middle decades of the twentieth century. 22:58.390 --> 23:00.960 Or celebrities took part. 23:00.960 --> 23:05.450 This is Elvis Presley campaigning for the March of 23:05.446 --> 23:06.176 Dimes. 23:06.180 --> 23:11.730 Or you can see Elvis again there. 23:11.730 --> 23:17.900 And most importantly, one of the most famous, 23:17.900 --> 23:21.170 probably the most famous of all polio victims, 23:21.170 --> 23:24.940 was President Franklin Delano Roosevelt, 23:24.940 --> 23:30.690 who was the leading figure in the establishment of this 23:30.689 --> 23:34.459 foundation, and the March of Dimes, 23:34.463 --> 23:39.833 and also another rehabilitation center in Warm Springs, 23:39.827 --> 23:40.917 Georgia. 23:40.920 --> 23:48.980 Let me just remind you that FDR was in fact himself a victim of 23:48.980 --> 23:52.490 polio, who was paralyzed. 23:52.490 --> 23:58.750 In 1948, a major discovery was made by three men who worked 23:58.752 --> 24:04.372 together as a team and shared the Nobel Prize amongst 24:04.368 --> 24:05.988 themselves. 24:05.990 --> 24:10.630 These were John Enders, Thomas Weller and Frederick 24:10.628 --> 24:14.488 Robbins, and they discovered that the 24:14.492 --> 24:20.382 poliovirus could be cultured in vitro in non-nervous 24:20.384 --> 24:22.014 human tissue. 24:22.009 --> 24:25.009 Now, why was that discovery critical? 24:25.009 --> 24:29.529 Well, first it meant that the cost of research plummeted, 24:29.528 --> 24:35.158 because you didn't need to have live monkeys to take care of in 24:35.157 --> 24:38.877 order to do experiments with the virus. 24:38.880 --> 24:44.490 It led soon to the discovery that the digestive tract, 24:44.490 --> 24:47.930 rather than the nose, was the portal of entry, 24:47.930 --> 24:52.230 and it led to the discovery of a phase in which antibodies 24:52.230 --> 24:55.930 could attack the virus in the open bloodstream. 24:55.930 --> 25:01.820 And it led to the discovery that poliovirus exists in three 25:01.821 --> 25:05.171 different serotypes: poliovirus 1, 25:05.173 --> 25:08.733 poliovirus 2, and poliovirus 3. 25:08.730 --> 25:13.180 And it was these discoveries that made possible the 25:13.178 --> 25:16.558 successful development of a vaccine. 25:16.558 --> 25:19.718 And this duly occurred in two major forms. 25:19.720 --> 25:23.910 This was a momentous development. 25:23.910 --> 25:30.460 The first was by Jonas Salk, and that was an inactivated 25:30.458 --> 25:36.408 injectable vaccine, tested in 1904 and administered 25:36.411 --> 25:40.461 successfully en masse in 1955. 25:40.460 --> 25:44.520 And Jonas Salk became a national hero and celebrity for 25:44.519 --> 25:48.429 this, on the cover of Time Magazine. 25:48.430 --> 25:52.750 Everyone talked about him, and indeed he was later to say 25:52.751 --> 25:57.541 himself that he didn't need the Nobel Prize because he was much 25:57.537 --> 26:00.467 more famous than the prize itself. 26:00.470 --> 26:05.510 Second was another vaccine, a competitor if you like, 26:05.509 --> 26:09.289 which was a live oral polio vaccine, 26:09.288 --> 26:14.708 developed by Albert Sabin, and tested in 1959 and '60, 26:14.710 --> 26:19.630 and administered en masse in the 1960s. 26:19.630 --> 26:23.210 Now both of these developments were funded by the National 26:23.212 --> 26:25.542 Foundation for Infantile Paralysis. 26:25.538 --> 26:30.298 You can see the role of the March of Dimes in leading to 26:30.297 --> 26:32.197 medical discoveries. 26:32.200 --> 26:37.150 Almost immediately after the development of these two 26:37.151 --> 26:42.011 vaccines, the goal of eradication was taken up as an 26:42.007 --> 26:43.337 objective. 26:43.338 --> 26:46.948 In the 1950s, already, Albert Sabin, 26:46.952 --> 26:51.292 for example, made eradication an article of 26:51.287 --> 26:52.317 faith. 26:52.318 --> 26:56.148 He said the goal--and I'm quoting--"is to completely 26:56.152 --> 26:59.052 eradicate poliomyelitis, to eliminate it, 26:59.046 --> 27:02.406 to make it disappear, to achieve ultimate 27:02.413 --> 27:04.283 eradication." 27:04.278 --> 27:09.178 Well, a major question was which vaccine? 27:09.180 --> 27:14.910 Should the campaign be based on Salk's IPV; 27:14.910 --> 27:18.710 that is, the injectable inactivated vaccine? 27:18.710 --> 27:23.500 Let me try to fix this in your mind. 27:23.500 --> 27:29.410 This is a picture of Jonas Salk, and as you can see he's 27:29.414 --> 27:35.224 holding--about to vaccinate someone with his injectable 27:35.222 --> 27:37.592 inactivated virus. 27:37.589 --> 27:39.939 And here we can see him at work. 27:39.940 --> 27:46.140 This is how Jonas Salk's vaccine operates with a syringe. 27:46.140 --> 27:49.510 It had a number of drawbacks. 27:49.509 --> 27:57.409 It was an effective public health measure and led to a 27:57.406 --> 28:00.086 robust immunity. 28:00.088 --> 28:03.608 But it was administered by injection, 28:03.608 --> 28:10.088 and in terms of being a worldwide public health tool, 28:10.088 --> 28:15.148 it required qualified vaccinators, and that made it 28:15.150 --> 28:21.020 too complicated and expensive for a worldwide campaign, 28:21.019 --> 28:25.819 especially in Third World countries. 28:25.818 --> 28:28.438 And since it was a killed vaccine, 28:28.440 --> 28:32.710 killed by formaldehyde, it would stimulate the 28:32.711 --> 28:38.491 production of antibodies, but it wouldn't cause what was 28:38.494 --> 28:43.814 termed mucosal immunity directly in the human gut. 28:43.808 --> 28:50.408 Then there was the alternative, which was developed by Albert 28:50.414 --> 28:55.374 Sabin, which was the attenuated live virus. 28:55.368 --> 29:00.048 This had--it was administered initially on sugar cubes that 29:00.049 --> 29:04.569 were a couple of drops put on them and then people downed 29:04.568 --> 29:06.988 them, especially children. 29:06.990 --> 29:13.020 Or else it was a pink liquid that was simply dropped with a 29:13.015 --> 29:15.815 dropper down your throat. 29:15.818 --> 29:20.118 And that could be administered at a fraction of the cost-- 29:20.118 --> 29:23.958 as I said, on sugar cubes or as a liquid-- 29:23.960 --> 29:28.800 and the only skill that was required of the vaccinator was 29:28.795 --> 29:33.815 the ability to count to two; because you dropped two drops 29:33.817 --> 29:35.267 into the throat. 29:35.269 --> 29:40.929 And that's the--it took half an hour to train a vaccinator using 29:40.932 --> 29:43.632 Albert Sabin's oral vaccine. 29:43.630 --> 29:49.410 But equally importantly the oral poliovirus caused a virus 29:49.412 --> 29:54.792 to be shed from the intestine into the environment; 29:54.788 --> 29:59.808 that is, it took root and flourished in the gut of the 29:59.811 --> 30:02.631 people, of the vaccinees, 30:02.625 --> 30:06.685 and as they shed they would spread, 30:06.690 --> 30:10.480 that is the virus, causing an asymptomatic and 30:10.480 --> 30:15.030 harmless infection in the guts of whole communities. 30:15.028 --> 30:18.018 Thereby you would raise the herd immunity, 30:18.020 --> 30:20.940 even in people who weren't vaccinated. 30:20.940 --> 30:25.690 So, you could miss people with Sabin's vaccine, 30:25.689 --> 30:29.509 and still reach entire communities. 30:29.509 --> 30:33.139 That was the vaccine, the major new tool, 30:33.144 --> 30:38.424 with its two different forms: Salk's injectable vaccine and 30:38.416 --> 30:40.686 Sabin's oral vaccine. 30:40.690 --> 30:45.830 But what the campaign relied upon was something in addition 30:45.825 --> 30:50.955 to the new scientific tools, and this was a new operational 30:50.961 --> 30:52.911 campaign strategy. 30:52.910 --> 30:56.620 And the campaign strategy, interestingly, 30:56.618 --> 31:01.458 was first devised in Fidel Castro's Cuba, 31:01.460 --> 31:06.080 and the campaign strategy provided a context in which oral 31:06.075 --> 31:09.715 polio vaccine could be maximally effective. 31:09.720 --> 31:14.880 This was taken up and was called the tool of National 31:14.883 --> 31:16.873 Immunization Days. 31:16.869 --> 31:19.369 Let's remember how they started. 31:19.368 --> 31:22.678 Instead of limiting immunization to those who 31:22.684 --> 31:26.834 received routine vaccinations from their physicians, 31:26.828 --> 31:33.278 the National Immunization Days took as axiomatic that there was 31:33.275 --> 31:37.325 very limited access to medical care, 31:37.328 --> 31:41.298 and so the idea was to not bring patients to the 31:41.297 --> 31:45.347 vaccinators but to take vaccine to the people. 31:45.348 --> 31:50.108 In 1962 in Cuba, the grassroots organizations of 31:50.109 --> 31:54.089 Castro's revolution, which were called Committees 31:54.093 --> 31:56.223 for the Defense of the Revolution, 31:56.220 --> 32:01.340 carried out house-to-house surveys to locate every child on 32:01.337 --> 32:05.827 the island of Cuba, and then vaccinators made a 32:05.833 --> 32:11.323 return visit to vaccinate every child who'd been located. 32:11.318 --> 32:18.078 This procedure morphed in the United States into what were 32:18.079 --> 32:23.539 called Sabin Oral Sundays, beginning at Tucson, 32:23.536 --> 32:24.956 Arizona. 32:24.960 --> 32:28.520 And, as you can imagine, these Sabin Oral Sundays 32:28.520 --> 32:32.450 weren't sponsored by Committees for the Defense of the 32:32.452 --> 32:37.142 Revolution, but rather by local and county 32:37.135 --> 32:41.885 chapters of the AMA, and its members volunteered 32:41.890 --> 32:45.060 their services, alongside those of local 32:45.063 --> 32:47.673 pharmacists, county health officials, 32:47.670 --> 32:51.970 nurses, school teachers, clergymen, the local press, 32:51.971 --> 32:53.521 and housewives. 32:53.519 --> 32:57.199 And the vaccine was administered in school 32:57.202 --> 32:58.282 buildings. 32:58.279 --> 33:01.779 This campaign, thus structured with the new 33:01.781 --> 33:06.201 tool of vaccine and the new organizational strategy of 33:06.201 --> 33:11.371 National Immunization Days, successful eradicated smallpox, 33:11.369 --> 33:16.669 first in the United States, and then in the Americas. 33:16.670 --> 33:23.510 In 1988, the World Health Organization then launched the 33:23.506 --> 33:28.226 Global Polio Eradication Initiative. 33:28.230 --> 33:31.730 At the outset, it was supported in particular 33:31.732 --> 33:36.192 by what was the equivalent of the Gates Foundation of its 33:36.192 --> 33:39.802 time, and that is the resources and 33:39.796 --> 33:45.796 international structure of the 32,000 clubs worldwide of Rotary 33:45.795 --> 33:48.925 International; which was an NGO, 33:48.930 --> 33:53.670 as I said, somewhat equivalent in its time to the Gates 33:53.665 --> 33:56.205 Foundation of our own day. 33:56.210 --> 34:01.220 The campaign also enjoyed the support of the CDC, 34:01.220 --> 34:04.850 of international agencies like the G8-- 34:04.848 --> 34:07.428 as it was then, it's no longer that, 34:07.430 --> 34:12.020 it's expanded--the African Union, various national 34:12.023 --> 34:16.513 governments, and an army of vaccinators. 34:16.510 --> 34:20.870 From the beginning, the Global Polio Eradication 34:20.869 --> 34:26.619 Initiative adopted the strategy of combining Sabin's oral polio 34:26.621 --> 34:31.721 vaccine with Cuba's operational device of community-wide 34:31.722 --> 34:33.952 immunization days. 34:33.949 --> 34:38.579 The goal was to provide the most susceptible populations on 34:38.581 --> 34:40.621 earth, small children, 34:40.615 --> 34:44.035 worldwide, every child on the planet, 34:44.039 --> 34:51.359 to be vaccinated with at least two doses of oral polio vaccine. 34:51.360 --> 34:56.200 Now, let's remember what a gargantuan effort this actually 34:56.199 --> 34:56.709 was. 34:56.710 --> 35:01.450 National Immunization Days were extraordinary events that 35:01.452 --> 35:06.452 necessitated the participation of 10 million people in their 35:06.449 --> 35:07.889 organization. 35:07.889 --> 35:13.359 Take the example of India, where the National Immunization 35:13.364 --> 35:19.614 Days became the largest single public health events in history; 35:19.610 --> 35:26.060 when as many as 93 million children were vaccinated on 35:26.063 --> 35:27.773 single days. 35:27.768 --> 35:35.818 Well, 1988 to 2003, the campaign made huge 35:35.820 --> 35:37.980 progress. 35:37.980 --> 35:42.700 In 1988, the World Health Organization estimated that 35:42.699 --> 35:49.029 there were 350,000 cases, worldwide, of paralysis from 35:49.027 --> 35:53.317 polio, and it believed the disease to 35:53.322 --> 35:56.432 be endemic in 125 countries. 35:56.429 --> 36:00.049 In 1988 itself, transmission was halted in 36:00.045 --> 36:00.835 Europe. 36:00.840 --> 36:04.600 In 1991, it was halted in the Americas, 36:04.599 --> 36:11.909 in 1997, in the Pacific region, and in 2001 there was a world 36:11.911 --> 36:18.491 record with a low of 483 recorded cases of paralysis in 36:18.494 --> 36:23.374 just four endemic countries: India, 36:23.369 --> 36:28.499 Pakistan, Afghanistan and Nigeria. 36:28.500 --> 36:33.490 Let me show you a map. 36:33.489 --> 36:36.269 This is 2008, as you can see, 36:36.273 --> 36:41.453 and the countries in red are those where polio is now 36:41.445 --> 36:44.545 endemic, and the ones in yellow are 36:44.550 --> 36:51.190 places that it spread to, from those endemic countries, 36:51.192 --> 36:52.672 in 2008. 36:52.670 --> 36:58.990 Well, there was a setback in 2003, and what did that 36:58.994 --> 37:00.364 indicate? 37:00.360 --> 37:03.390 Already vanquished in the industrial world, 37:03.389 --> 37:08.909 poliomyelitis, in 2003, remained endemic only 37:08.911 --> 37:16.041 in some of the most unsanitary, poverty stricken and insecure 37:16.039 --> 37:18.209 places on the planet. 37:18.210 --> 37:22.210 This is one reason that it's a mockery to think of 37:22.206 --> 37:27.016 poliomyelitis as a disease of the affluent and the clean. 37:27.018 --> 37:34.388 Poliomyelitis had been driven back to the war-torn and remote 37:34.389 --> 37:39.159 areas of Pakistan, to Muslim dominated states of 37:39.157 --> 37:43.257 northern Nigeria, northern Sindh in Pakistan, 37:43.259 --> 37:48.399 and the states of Bihar and Uttar Pradesh in India. 37:48.400 --> 37:53.560 Now, the Muslim states of Nigeria, and especially Kano, 37:53.561 --> 37:58.721 as we'll talk about in a moment, were the most striking 37:58.724 --> 37:59.684 cases. 37:59.679 --> 38:04.129 There, in northern Nigeria, the campaign was actually 38:04.132 --> 38:07.642 halted by a boycott, an organized boycott, 38:07.643 --> 38:09.703 for thirteen months. 38:09.699 --> 38:13.619 As a result, in Nigeria, the disease flared 38:13.623 --> 38:18.393 up, causing hundreds of cases of acute paralysis. 38:18.389 --> 38:21.989 And alarmingly it spread from Nigeria widely, 38:21.989 --> 38:26.719 causing outbreaks of paralysis in eighteen countries in West 38:26.717 --> 38:30.907 and Central Africa, that had previously had been 38:30.911 --> 38:32.911 pronounced polio free. 38:32.909 --> 38:38.669 Well, what were the problems that emerged in 2003? 38:38.670 --> 38:45.400 I'm going to say that they were operational, religious, 38:45.402 --> 38:48.772 political and biological. 38:48.768 --> 38:54.678 Operationally you can see the problems that would emerge in a 38:54.679 --> 38:58.949 place like Afghanistan, and why that would be a 38:58.954 --> 39:03.354 recalcitrant place for public health officials to attempt to 39:03.351 --> 39:06.781 eradicate a disease as entrenched as polio. 39:06.780 --> 39:13.960 War and lack of security made vaccination campaigns dangerous 39:13.958 --> 39:17.188 and sometimes impossible. 39:17.190 --> 39:21.200 But let's look for a moment at a different place. 39:21.199 --> 39:25.889 And this is a map of Nigeria, if you imagine the country, 39:25.893 --> 39:31.093 and that's the state I want to talk about, the state of Kano in 39:31.088 --> 39:32.848 northern Nigeria. 39:32.849 --> 39:41.069 There we see a problem that's political and religious. 39:41.070 --> 39:46.880 Muslim leaders in Kano--and that's in a country--the 39:46.876 --> 39:52.226 government of Nigeria is Christian-dominated. 39:52.230 --> 39:55.800 The states of northern Nigeria, however, 39:55.800 --> 40:01.760 are Muslim, and they were suspicious in northern Nigeria 40:01.762 --> 40:07.472 about Western intentions, especially after the launching 40:07.465 --> 40:12.925 of war in Afghanistan and Iraq, and people began to preach, 40:12.932 --> 40:17.522 religious leaders, that oral polio vaccine, 40:17.518 --> 40:23.158 these drops were not a measure of public health, 40:23.159 --> 40:28.719 but instead a sinister plot to sterilize Muslim children by 40:28.715 --> 40:33.565 poisoning them, so that Islam would recede from 40:33.572 --> 40:38.122 the earth and Christianity could replace it. 40:38.119 --> 40:44.949 And this whole thinking was ramped up by the issue raised by 40:44.954 --> 40:51.704 the pharmaceutical giant Pfizer, which had conducted unethical 40:51.695 --> 40:55.835 testing in Nigeria, in a way that inflamed public 40:55.844 --> 40:59.764 opinion especially, and led to a major lawsuit 40:59.757 --> 41:01.627 against the company. 41:01.630 --> 41:04.320 Furthermore, since the traditional dogma 41:04.318 --> 41:08.388 about poliomyelitis held that it was an insignificant public 41:08.385 --> 41:11.275 health problem in the tropical world, 41:11.280 --> 41:17.000 it was difficult for many to understand why the international 41:17.000 --> 41:22.720 community was so intent on trying to rid Nigeria of polio. 41:22.719 --> 41:26.719 The Nigerians themselves regarded other disease as much 41:26.717 --> 41:29.677 greater causes of death and suffering. 41:29.679 --> 41:34.509 Why was the international community not concentrated on 41:34.507 --> 41:38.977 dealing with malaria, tuberculosis and HIV/AIDS? 41:38.980 --> 41:44.750 Why all this attention to polio, that seemed to them a 41:44.750 --> 41:47.690 relatively minor problem? 41:47.690 --> 41:54.180 The Emir of Kano was unable to discern benign intentions also 41:54.179 --> 41:58.289 when it transpired that industrial, 41:58.289 --> 42:03.129 predominantly Christian nations, were vaccinating their 42:03.128 --> 42:07.338 own populations instead with Salk's vaccine-- 42:07.340 --> 42:12.560 that is, the IPV--while insisting that Nigerians receive 42:12.556 --> 42:14.356 the oral vaccine. 42:14.360 --> 42:17.510 Why on earth was that? 42:17.510 --> 42:21.350 Finally, opposition to the vaccination campaign, 42:21.349 --> 42:24.389 promoted by the Christian-dominated federal 42:24.389 --> 42:28.029 government of Nigeria, served as a proxy for 42:28.025 --> 42:32.545 sectional, political and religious discontents in the 42:32.545 --> 42:34.975 minority northern states. 42:34.980 --> 42:39.710 So, the result was a boycott of the anti-polio campaign, 42:39.710 --> 42:45.250 and it lasted until 2004, at which time Muslim operated 42:45.253 --> 42:52.033 laboratories in Indonesia agreed to supply vaccines to Nigeria, 42:52.030 --> 42:56.960 and other Muslim operated laboratories in India analyzed 42:56.963 --> 43:00.823 the vaccine previously supplied to Kano, 43:00.820 --> 43:05.390 and found it to be harmless, at which point prominent Muslim 43:05.394 --> 43:10.364 leaders around the world pressed their co-religionists in Nigeria 43:10.358 --> 43:13.458 to support the international effort. 43:13.460 --> 43:18.550 But by then considerable harm had been done to the campaign. 43:18.550 --> 43:22.870 It was not clear either that large numbers of Muslim parents 43:22.867 --> 43:27.037 would ever again allow their children to be immunized, 43:27.039 --> 43:31.759 or that the spread of the virus beyond Nigerian borders was 43:31.760 --> 43:34.610 something that could be reversed. 43:34.610 --> 43:38.530 Let's say that deals then with political and religious 43:38.532 --> 43:39.422 obstacles. 43:39.420 --> 43:43.550 Then there were biological ones. 43:43.550 --> 43:47.100 And to illustrate those, let me go somewhere else. 43:47.099 --> 43:54.199 And this is Uttar Pradesh, in a Muslim-dominated state in 43:54.195 --> 43:55.205 India. 43:55.210 --> 43:59.460 And again you see there the issue of Muslim suspicions and 43:59.460 --> 44:01.550 resistance to vaccination. 44:01.550 --> 44:06.160 But I want to turn from those--imagine all of that going 44:06.155 --> 44:11.345 on--but I'd like to look at some biological issues that emerged 44:11.349 --> 44:13.359 in places like this. 44:13.360 --> 44:18.400 The first was whether polio turned out to be more 44:18.400 --> 44:21.340 complicated than smallpox. 44:21.340 --> 44:24.470 Because smallpox had only one serotype; 44:24.469 --> 44:28.659 poliovirus has types 1,2 and 3, and there's no crossover 44:28.663 --> 44:31.183 immunity from one to the other. 44:31.179 --> 44:34.619 So, it was a more complicated disease than smallpox. 44:34.619 --> 44:36.709 That was a first problem. 44:36.710 --> 44:40.790 And this emerged in the form of what kind of vaccine do you use; 44:40.789 --> 44:45.069 one that's monovalent, attacking developing resistance 44:45.065 --> 44:49.335 against only one type of poliovirus, or polyvalent? 44:49.340 --> 44:54.310 Should it be try to immunize you at once against one, 44:54.306 --> 44:56.786 two, or all three types? 44:56.789 --> 45:01.439 It turned out that polyvalent vaccines, for complicated 45:01.436 --> 45:04.186 reasons, weren't so effective. 45:04.190 --> 45:09.280 Another was a problem of monitoring and surveillance. 45:09.280 --> 45:14.310 Unlike smallpox, the vast majority of polio 45:14.313 --> 45:17.433 cases were asymptomatic. 45:17.429 --> 45:22.449 And then there was a problem called "interference". 45:22.449 --> 45:26.699 Children were found to be vaccinated twenty and 45:26.697 --> 45:31.217 twenty-five times, and still not to have developed 45:31.221 --> 45:33.531 an immunity to polio. 45:33.530 --> 45:34.640 Why was that? 45:34.639 --> 45:38.689 It turned out that in unsanitary tropical conditions, 45:38.690 --> 45:42.490 the intestinal flora of other viruses, 45:42.489 --> 45:47.919 particularly enteroviruses, in the digestive tract, 45:47.920 --> 45:54.800 could be so dense that the poliovirus in the vaccine would 45:54.804 --> 46:00.964 be unable to establish an infection and therefore an 46:00.963 --> 46:03.383 immune response. 46:03.380 --> 46:08.320 There were other problems that emerged in these turbulent 46:08.324 --> 46:13.634 years, after 2003--turbulent for the Global Polio Eradication 46:13.625 --> 46:14.945 Initiative. 46:14.949 --> 46:20.689 One was that live viruses, the Sabin poliovirus--remember, 46:20.688 --> 46:26.528 it's a live vaccine--it was unlike the smallpox vaccine. 46:26.530 --> 46:29.750 The smallpox vaccine, as you know, 46:29.751 --> 46:35.121 was a vaccine from cowpox, that had a crossover immunity 46:35.119 --> 46:40.879 to smallpox, and cowpox is not a serious human disease. 46:40.880 --> 46:45.930 With polio instead, what's administered through the 46:45.934 --> 46:50.824 oral vaccine is a live virus; in attenuated strains, 46:50.815 --> 46:53.825 yes, but it still is the live virus, 46:53.829 --> 46:58.839 and therefore there is always the possibility of the virus 46:58.835 --> 47:02.695 mutating and reverting to a virulent form. 47:02.699 --> 47:07.719 And this indeed happened, causing outbreaks of what's 47:07.721 --> 47:11.971 called vaccine-associated paralytic polio. 47:11.969 --> 47:15.209 This possibility wasn't just theoretical. 47:15.210 --> 47:19.630 It happened in the Philippines, in Madagascar, 47:19.628 --> 47:22.378 in China and in Indonesia. 47:22.380 --> 47:27.260 Reversing progress against the disease, outbreaks of that kind 47:27.260 --> 47:28.860 occasioned a quip. 47:28.860 --> 47:33.810 The quip was that it was impossible to eradicate polio 47:33.813 --> 47:36.903 without the oral polio vaccine. 47:36.900 --> 47:42.830 But it was also impossible to eradicate polio with it because 47:42.831 --> 47:47.481 the vaccine itself led to outbreaks of polio. 47:47.480 --> 47:51.620 So, vaccine-associated poliovirus implied something 47:51.619 --> 47:55.019 serious, that the campaign against 47:55.016 --> 47:59.686 poliomyelitis could have no logical endpoint, 47:59.690 --> 48:03.390 because it would always be necessary to immunize 48:03.393 --> 48:08.043 populations against epidemics that could be initiated by the 48:08.041 --> 48:09.541 vaccine itself. 48:09.539 --> 48:12.569 A very paradoxical situation. 48:12.570 --> 48:16.900 And the difficulty is all the more intractable because people 48:16.898 --> 48:21.298 with immunodeficiency disorders can continue to shed the virus 48:21.300 --> 48:23.970 for as long as ten years or more. 48:23.969 --> 48:27.309 If the campaign were ever allowed to lapse, 48:27.309 --> 48:31.579 the accumulation of non-immunized susceptibles could 48:31.579 --> 48:36.429 result in devastating virgin soil epidemics among those who 48:36.434 --> 48:38.114 had no immunity. 48:38.110 --> 48:41.800 So, for this reason critics have argued that the WHO 48:41.804 --> 48:45.214 campaign involved a semantic trick with the word 48:45.210 --> 48:47.240 "eradication." 48:47.239 --> 48:50.579 Traditionally, eradication had always implied 48:50.579 --> 48:54.679 the cessation of the need to maintain public protective 48:54.679 --> 48:56.729 public health policies. 48:56.730 --> 49:00.840 But vaccine-associated polio, paralytic polio, 49:00.836 --> 49:06.216 meant that planners for this campaign would have to continue 49:06.221 --> 49:08.961 immunization indefinitely. 49:08.960 --> 49:13.400 The traditional criterion that eradication implied the end of 49:13.396 --> 49:16.646 prophylactic measures was quietly dropped. 49:16.650 --> 49:20.050 And then there are the problems about certification and 49:20.047 --> 49:20.927 eradication. 49:20.929 --> 49:25.359 Poliovirus is notorious for being silent and undetected in 49:25.355 --> 49:28.375 its circulation, at the other end of the 49:28.382 --> 49:30.482 spectrum from smallpox. 49:30.480 --> 49:35.330 So, how would you be able to actually confirm that there were 49:35.327 --> 49:36.617 no more cases? 49:36.619 --> 49:42.109 And it's also true that another problem, that symptoms of 49:42.108 --> 49:47.598 paralytic- acute flaccid paralysis can be caused by other 49:47.599 --> 49:49.069 conditions. 49:49.070 --> 49:50.380 They're on your handout. 49:50.380 --> 49:54.220 I won't mention them because I'm rapidly running out of time. 49:54.219 --> 49:59.009 But in my last thirty seconds I would say that the history of 49:59.007 --> 50:03.477 Global Polio Eradication Initiative demonstrates that the 50:03.476 --> 50:08.306 original optimistic belief, that polio, like smallpox, 50:08.313 --> 50:12.093 can be readily eradicated by vaccination, 50:12.090 --> 50:13.970 was misplaced. 50:13.969 --> 50:18.439 Smallpox is exceptionally vulnerable to attack. 50:18.440 --> 50:22.980 It has no animal reservoirs, no range of serotypes that 50:22.976 --> 50:25.576 confer no crossover immunity. 50:25.579 --> 50:30.379 Its symptoms were almost always memorable and florid for the 50:30.384 --> 50:31.284 sufferer. 50:31.280 --> 50:35.000 It gives rise in survivors to a lasting immunity, 50:35.003 --> 50:39.663 and the vaccine used to attack it is effective after a single 50:39.655 --> 50:40.505 effort. 50:40.510 --> 50:45.900 Polio is a far more formidable enemy that reminds us that the 50:45.904 --> 50:50.764 original eradicationist perspective may be illusory. 50:50.760 --> 50:55.490 The human condition is to be surrounded by near infinity of 50:55.485 --> 50:58.985 infectious, constantly evolving microbes. 50:58.989 --> 51:03.269 Occasional final victories are possible, but they should be 51:03.269 --> 51:06.809 celebrated as exceptions, rather than regarded as 51:06.811 --> 51:10.061 successive steps to a disease-free Eden. 51:10.059 --> 51:14.889 The normal state is one of vigilance, to minimize harm and 51:14.893 --> 51:16.423 achieve control. 51:16.420 --> 51:22.040 Polio seems to me unlikely soon to follow smallpox by becoming 51:22.036 --> 51:27.006 the second infectious disease ever to be eradicated. 51:27.010 --> 51:30.670 That would be--if I had time, I'd talk more about it. 51:30.670 --> 51:31.450 But I don't. 51:31.449 --> 51:32.869 So, let's stop there. 51:32.869 --> 51:36.799 And I don't want to make a prediction, but I think we need 51:36.804 --> 51:39.914 to see how complex eradication actually is. 51:39.909 --> 51:44.949 And polio isn't like smallpox; and many other diseases aren't. 51:44.949 --> 51:49.999