Majority Indians have natural immunity. Vaccinating entire population can cause great harm

For recovered Covid patients, the vaccines provide no benefit and some harm. It is thus unethical to vaccinate them.

Health workers prepare for the dry run of COVID-19 vaccine at a community centre, in Gurugram, on 7 January 2021 (representational image) | PTI Photo

As we start 2021, the Covid-19 epidemic in India has progressed to a point where a near majority of the population has developed immunity to the virus. Though too many have died, India’s Covid death rate is, fortunately, lower than many other countries. With the vaccine roll-out imminent, there are reasons for optimism after a challenging year.

The primary question at hand for Indian Covid response policy planners is how best to use the vaccine — roll-out for which in India begins from 16 January and will target three crore health staff  — to minimise the harm from the disease until the end of the epidemic. Given the size of the population and the rate of production of the vaccine, it may take a considerable amount of time to vaccinate the entire population. So it will be necessary to choose who receives priority.

Despite the deployment of the vaccine, many countries – including the US and UK – continue to impose lockdowns as the primary means of controlling the virus’s spread. The results have not been good, with both cases and deaths rising despite the shuttered businesses, schools, and places of worship. Indian policy planners should take full advantage of these bad examples and continue to avoid lockdowns that have devastated the lives and livelihoods of millions of poor people throughout the country.

We know from the mortality statistics that the Covid infection poses the greatest risk to older populations. Worldwide, the infection survival rate for people under 70 is 99.95 per cent, while the analogous number for those aged 70 and over is 95 per cent. So, the only ethical choice requires offering the vaccine to people aged 70 and older first, as well as to the frontline health workers who care for Covid patients.

The problem is that, with 88 million elderly citizens in India, there will not be enough doses in the immediate future to vaccinate them all for months to come. We argue that inoculating only people who have not been previously infected provides an efficient way to target the vaccine at those who will benefit from it most.

Immunity after recovery from Covid

The scientific evidence is overwhelming that natural immunity attained after recovery from Covid infection is effective and long lasting. The immune system responds to infection by various mechanisms, including the production of specific antibodies, T-cells, and B-cells to protect nearly every recovered Covid patient from reinfection. After almost a year of pandemic, globally, only 34 cases and two deaths have been definitively identified as reinfections at the time of writing, out of the 90 million Covid cases and likely hundreds of millions of infections worldwide.

Vaccines cause the immune system of those inoculated to mimic the immune response that natural infection induces. While the immunity conferred by the Covid vaccines documented in the clinical trials is excellent, it is not as effective as the immunity conferred by natural infection.

Furthermore, those who have already developed immunity to Covid through natural infection are extremely unlikely to develop additional immunity from vaccination. For instance, in the Pfizer randomised trial, the vaccine was tested in previously infected patients to check for its safety in that group. But those same patients were excluded from the analysis of efficacy, presumably because the scientists understood that the vaccine would confer no additional benefit to them.

Every vaccine has some side effects, and though the approved Covid vaccines are safe, they are no exception. Most of the side effects are mild – soreness at the injection site, aches and pains from the immunological reaction – but very rarely, severe adverse events do occur. For recovered Covid patients, then, the vaccines provide no benefit and some harm. It is thus unethical to vaccinate them.

India is reaching very high level of natural immunity

These considerations are not merely of theoretical interest because an enormous proportion of the Indian population has already been infected and recovered. While the officially reported figure of Covid cases in India is around 1.4 crore, mathematical models imply that more than 50 per cent of the Indian population may have developed natural immunity to the virus.

This fact is corroborated by serological tests for Covid antibodies carried out commercially on a large scale by Thyrocare. The founder of Thyrocare, Dr A. Velumani, says that “nature… already has immunised, freely, silently 70% Indians”.

Though this may sound like bad news, since it implies that nearly a billion Indians have already been infected, the silver lining is that the vast majority have recovered from infection and have lasting immunity to reinfection. They will likely be better protected from Covid over a longer period of time than those who achieve immunity via vaccination since it is not clear how long the vaccination-induced immunity lasts.

Checking for previous infection is simple. Before vaccination, patients should be asked if they have been previously infected, and if the answer is no, an inexpensive test for antibodies should be administered. Only if that test is negative should the vaccine be administered. This procedure will not capture all previous infections since antibodies fade after a few months, and many infected people were never identified as cases. Still, this procedure will nevertheless spare a large number of people from unnecessary vaccination.

Thus, reserving vaccine doses for people who have not been previously infected could solve the problem of excess demand for the vaccine by the vulnerable in the early months of the vaccine roll out when not enough doses will be available for all.

Prioritise the vulnerable for vaccination

In a disease with high asymptomatic cases and low morbidity or infection fatality rate, the first goal of vaccination is to reach herd immunity and not 100 per cent eradication through universal vaccination — that would be simply impossible. The only human virus that has been entirely eradicated from the face of the earth is smallpox, and that effort took decades despite the availability of an excellent vaccine. Chasing this impossible goal would impose great harm to India.

By contrast, a swift, focused protection strategy of vaccine administration, which prioritises the most vulnerable who have not been previously been infected, would reduce death rates from Covid infection to nearly zero and is a far better strategy.

Once the vulnerable are protected, even while the vaccine is administered to the less vulnerable younger populations, the Disaster Management Act’s lockdown restrictions should be lifted fully and forever. The economic, physical, and emotional harms from the lockdown far exceed the mortality and morbidity risks from Covid infection for less vulnerable people. Since either vaccine-induced or natural immunity would already protect the vulnerable, there would be no ethical reason for the remaining lockdown restrictions to be in place.

Sanjiv Agarwal is the founder of the Good Governance India Foundation, Mumbai. Jay Bhattacharya is Professor of Medicine at Stanford University. Views are personal.