'It's time to exit the lockdown, we cannot have a protracted lockdown policy,' says Dr K Srinath Reddy in a interview with FIT.
President of Public Health Foundation of India, Dr Reddy has been advising the government in various aspects on India's response to the novel coronavirus pandemic. In a conversation with FIT, Dr Reddy also spoke about how, "we should not shy away as a nation from facing the possibility of a community transmission." He also mentioned that herd immunity cannot possibly be a public health strategy.
Many studies and models we have come across with, seem to suggest that at the most conservative estimate, the peak in India is at least 2-3 months away. What should be India’s exit policy?
The purpose of the lockdown was to slow down the transmission of the virus and give us time to build up a stronger health system response and a sturdier social response. It’s time to move on to the next phase where we continue to implement a large number of personal protective measures as well as public health measures in order to slow down the transmission, but with resumption of economic and social activities as appropriate to each region of the country and district of the country.
The Health Minister recently said that India has avoided community transmission and that’s because of our robust contact tracing efforts. But is that true of areas like Mumbai, Delhi and parts of Ahmadabad?
They are describing it as local transmission and saying it is coming from foreign travellers, their contacts and their secondary contacts and so on and so long as they are able to trace those contacts, they feel it is local transmission. But we should not fight shy as a nation of facing the prospect of community transmission. Every country has gone through, at some level or other, some form of community transmission. The virus is going to stay with us. It is not in a permanent lockdown in terms of neither is it imprisoned or exorcised from our community or the planet. We have to make sure the transmission continues to be very slow so we do not have too many people suffering serious consequences. We protect the most vulnerable while resuming our economic and social activity. Till the time a vaccine arrives that offers a much larger protection. But the fact that community transmission is inevitable is something we all must recognise and proceed with that.
Is herd immunity a logical public health strategy in a country like India?
There is a lot of misunderstanding about what herd immunity is. Firstly it depends a lot upon the R Nought or R0 (rate of transmission). And the more the R0, the greater the immunity threshold. If you take polio and smallpox, the R0 was 5-7. And the herd immunity threshold was 80-85 % of the population. Being a very severe disease, it has taken us 100 years to achieve that, not through acquired immunity through infections but through vaccines.
In terms of Ebola and Influenza, the R0 was 1-2. There the herd immunity threshold is 30-50 percent.
For COVID-19 R0 is 3 when it started. So the herd immunity threshold is 60-70%. Here as well, we need to clarify a few things:
1st, it is herd protection and not herd immunity. Let’s say people in Delhi - 50 -60 percent are infected, and the rest develop that kind of immunity. But suppose a person from Delhi travels to Ranchi or Raipur, where the infection rate has only been 20-30 percent, so that community does not have the herd immunity to confer to this person. So this person from Delhi is still vulnerable. So it is the herd that has protection characteristics if it is stable, but not the unprotected individuals of the herd if they travel to another herd.
We also do not know, these antibodies we are developing, to what levels will they confer immunity, what duration will that immunity last, because we know influenza immunity does not last long, also we need to know if we need cell immunity or whether these antibodies are enough.
With multiple questions hanging around this new virus, I don’t think we can place our bets on this herd immunity to get us out of trouble.
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