 Hello and welcome to news click. Today we're going to discuss again the question about herd immunity and whether without vaccines herd immunity is possible. There have been articles, for example, which have been written recently that they will be moving towards herd immunity because numbers have gone, what is called set of positivity numbers have gone above 50% and so on. The question before you is a natural progress to herd immunity and this has come out again and again from the Barrington Declaration in the US by a certain set of people to now Professor Patel from Harvard also talking about in this vein, as well as various others that if you have sufficient number of infections in the country or in a place we will get herd immunity. This seems to neglect the fact that we do not know how long this immunity stays and arguments which we have discussed earlier that herd immunity is not possible is not enough that if we want to stop the pandemic will have we need vaccines. So when how do you see the landscape today with respect to this. So, as you point out probably this is the next page if you like of months old conversation, I won't say debate, because if I said debate, it would imply that there is enough evidence and data on the basis of which to have a substantive conversation. And the sad part is that there really isn't the cases of Manaus and Sao Paulo which you refer to as Amazonas the province of Amazonas in Brazil. So, the paper that you're referring to is actually not about Amazonas, it is about the city of Manaus and their own comparison in the paper is with the city of Sao Paulo. Okay. And there are really interesting differences there, which they use to make the argument that even with an extremely widespread infection, as many as two thirds of the community infected at one point they infer the infer. Cases and mortalities were still evident. So, in fact, the bottom line of the paper this past week or so in science at the paper actually makes the point that despite a high prevalence of infection. The case numbers and mortality figures were still very much in evidence as socio medical problems. And in fact there is a recurrence of the pandemic epidemic in Manaus. In fact, right now, oxygen cylinders are not available. The hospitals are full. Of course it's one of the relatively poor provinces and where there's a lot of poverty, people are closely living very close together and so on. So there's a basically all the social problems exist but they have now seen even after that earlier really high numbers, they're seeing again a recurrence of these numbers. So it would seem to indicate that actually if there was immunity, that immunity over a period of time may not be there with a lot of people. Absolutely. On the other hand, we have the repeated references to India and that after all is what we are going to be primarily interested in in these conversations. And where zero survey after zero survey nationwide zero surveys of all sorts nationwide zero surveys from the Indian Council of Medical Research, which takes a few samples in very large number of dispersed locations, or a zero survey that has been recently found from the Council of Scientific and Industrial Research where CSI employees and their families have been studied in all of those. The general interpreted claim is that infection is extremely widespread in India, yet our case numbers are as large as those rates of infection would seem to predict, and that we have had only one peak in September for infection our case numbers are now steadily falling, despite unchanged or improved testing and and so on and so forth. And therefore, our actual mortality rates as a fraction of infected people is far below the global average which seems to be about a quarter to a third of a percent, and our seems to be about a 10th of a percent. And therefore, the argument goes, Indians, whatever the idea of Indians, given all our disparities might mean in this context, Indians are resistant to the severe outcomes of COVID-19 and many of us are likely to be immune and therefore, our national vaccination program, the largest in the world for COVID-19 is effectively addressing an already vanquished foe to use some of the more dramatic imagery that has been proposed. The difficulty with this particular argument is underlined by the Manaus data that you refer to, which is that there is a great deal of noise of variation in the data. We've talked about variations in zero surveys in the past in these conversations, where in the same neighborhoods, one part of the neighborhood shows as low a figure as 30%, another part of the neighborhood shows another part of a municipal ward shows numbers as high as 70%. Clearly, coupled to the fact that the dispersal efficiency of this virus seems to be highly variable, unlike say the measles virus or unlike say the influenza virus, given all that, I think perhaps a certain amount of at least caution about interpreting small sample size data sets in macro sociological terms is in order. And if that we keep as a note of caution, then what the Manaus study couples as an additional caution is they're finding that there seems to be a waning of antibody responses in people who were exposed after a few months. And those really are the underpinnings for erring on the side of caution for not assuming large scale widespread protective immunity, leave alone the breakpoint of herd immunity where infection transmission effectively drops below levels that need to be worried about at the public health In all of this, it is important to be cautious. And therefore, I think that these calls for Oh, don't worry about the vaccine herd immunity is already kicked in and so on and so forth. Are premature and poorly founded on data to say the least. The other part, which is again results which are coming out that there are new variants that are appearing. Some of them are seem to be easily controlled, possibly by the vaccines we have. And we are talking about really the Moderna and the Pfizer by biotech vaccine, because those are the ones which seem to be at the moment more used in the advanced countries therefore more studied etc etc. But if you look at that, there is also the Pfizer biotech results which seem to show that against the South is particular variant which is now visible in South Africa could be another places as well. There is also Brazilian variant which also seems to be quite, quite similar that they that Pfizer vaccine did not produce a strong immune response, a weaker immune response will it be sufficient, not set question mark, but it did not produce as strong a response as the other, no other variants normally do. So, could it be that you will need tweaks to our back existing vaccines as well to meet variants. In fact, is it a part of the larger evolutionary struggle between the virus and us. So, your question again underlines my perpetual worry about the extremely sketchy quantities of evidence on the basis of which we make these facile interpretations. Satya, we are not scientists, we have to do with as a matter of course. Let's remind ourselves of the evidence. Moderna has claimed that they have tested vaccine blood serum samples and find that the three major variants that are under discussion at the moment, is the UK variant so called the so called South African variant and the so called Brazilian, well I don't think they've tested the so called Brazilian variant. But certainly the so called UK and South African variants they've tested and their vaccine samples provide protection. We don't know what the basis of this data assertion is. Let's keep that in mind as well. Biontech Pfizer have said that the so called UK variant is well protected against the so called South African variant, perhaps not quite as much but they are very cagey and cautious about what exactly they claim about it. Keep in mind that a proper public sector South African data set from Professor Penny Moore's group in South Africa has tested naturally infected people's blood against the UK and the South African variants, and finds that the South African so called variant is somewhat resistant to protection by blood samples from naturally infected people. All of this is a quantitative mess because keep in mind that what we are saying is it is less well protected, it is a little bit better protected and so on and so forth. What we are missing here, and I remind you of our conversations over these past months again, is that we have not been quantifying measuring amounts of the protective set of antibodies, either in naturally infected individuals or in vaccines. We have not been correlating the levels of protective antibodies, the actual quantitative levels of these protective antibodies with the extent of protection. And yet, all the variant related information is quantitative, a little more, a little less, how much is too little to worry about, how much is more and therefore we should worry about. We don't have good evidence on any of this. What we seem to have at the moment is that a substantial amount of the virus circulating is still by and large amenable to most vaccine related immune responses. So should all of us be taking the first generation vaccines. Absolutely, yes. Do we expect that need will arise for next generation vaccines and again, I remind you of our conversations from the past, where we've said this is going to be only the first generation vaccines, we are going to be in light in all likelihood over the years, using next generation vaccine using next generation vaccines, either because vaccine mediated protection wins after a year or so, and or because the virus changes. And I think what we are seeing is the early days of that. So are we going to need variant vaccines absolutely yes. And should we therefore now rush into the judgment of saying, Oh, these old vaccines are not useful any longer now we need new vaccines. No, not at all. What we should do is take the current vaccines and demand that our governments across the board make provision for public interest public health vaccination on the one hand, and public interest public health. We are monitoring of immune responses so that we know the quantitative basis of all these claims and counterclaims much better than we currently taking a step back from what you said, let's put it this way, that we are not going to see vaccines which will give, at least not in the future, a lifetime protection, that is something that we can perhaps conclude that our immune response is not going to be lifelong to protect us against such infections. Secondly, the both the vaccines will change meaning improve what you call second generation, generation vaccines, but it's also possible, the virus will also change. So this would continue to be one of the diseases which are endemic, likely to be endemic unless you are lucky and it sort of goes away by miracle at some point, and the cycle of vaccination and low level endemic infection is likely to stay. This will join the various other diseases that we have as humanity, and this will add to that kitty. I'm beginning to sound like a broken record because I'm saying you will remember that many months ago, we had a conversation in which we came to the conclusion that the most likely out resolution of the pandemic was going to be that the disease will endemic that we will see smoldering, you know, a little low level transmission outbreaks here and there some with variant virus. We will make a quick vaccine against it, we will respond to it, we will bring it under control in the public health sense, but we will live with the virus, the virus will live with us. All said and done, this virus has three cousins who already live with us that we exchange through a common cold. There are three other coronavirus family members that give us the common cold amongst many, many other viruses that give us the common cold. So absolutely yes, in short. Well, that took a couple of hundred, maybe even a thousand years or so for the coronavirus to be tamed. Hopefully, this will be faster. I think the latest was supposed to be 150 150 years back that we got the coronavirus coming to human population. Hopefully, vaccination will give us a crash course by which we'll reach that stage for faster. But coming back Satyajit to perhaps the discussion that you'd have in the future, that all of this has brought out humanity, not just in the global south, that infectious disease has not gone away. The idea, which is the famous book that hotels have written the forgotten diseases that these are not forgotten diseases, the effect, they used to affect four to five billion people anyway because that was the global south, and now affect more than seven billion human population and coronavirus has shown that infection infectious diseases haven't gone away, and this will continue therefore in battle between the two, and we have to look at therefore public health and not an individualized medicine. This is something that I have to come back to you next week, because I think both in terms of the larger issues can the global economy recover, or can people's health recover. Both of these are connected to how we look at public health issues in the future. Thank you very much for being with us, and we hope to see you again next week. This is all the time we have for news click do keep watching news click and do visit our website.