Has India started approaching the elusive state of gaining herd immunity against the Coronavirus? The results from the seroprevalence survey carried out across the national capital seem to indicate that herd immunity may be a possible explanation as to why infection rates across the country have been going down for quite some time in official figures. The survey, which checks for the presence of antibodies against the Coronavirus, found that 56.13 per cent of the people in the city have developed these antibodies. This survey had a sample size of 28,000 across 11 districts in India, making it the largest sero-survey of its kind that has been carried out in the nation. While similar surveys have been carried out across the country, Delhi has reported the highest levels of seropositivity.
At face value, it may be easy to take this as a sign that India has been successful in building-up its herd immunity at a time when the world is suffering from yet another wave of the pandemic. But this possible build-up of immunity is not by design. The only known example of an 'intentional' move towards achieving herd immunity in the world met with disastrous consequences as Sweden had to call off its minimum restrictions approach in the midst of a surging death count. If India has indeed achieved such immunity, it would also in some ways indicate the failure of virus control measures as there are many indications that India has or had a high amount of undetected cases which may have been asymptomatic or mild in nature. Many experts have questioned as to whether the world's largest lockdown (and among the strictest) was actually effective in controlling the spread of the virus. Several mistakes may have contributed to the spread of the virus to such a wide extent but the important one to note is that at a certain stage during the unlock phases, doubt and complacency loosened the hold of masking and social distancing rules over parts of the population. Besides those who could not, for various reasons, stay indoors and suitably socially distanced, many simply abandoned safety measures over time for reasons of inconvenience or because they fell into believing conspiracy theories that either showed the pandemic to be an exaggeration of a much smaller, less dangerous outbreak or a hoax in its entirety, cooked-up for a variety of supposed reasons.
Indeed, such an attitude towards the pandemic has also been seen as a significant impediment towards the mass vaccination campaign that is currently underway in the nation with many showing a reluctance towards taking the vaccine as official infection numbers dropped across the country. It is important to note that even this assumption of herd immunity, regardless of how it was achieved, is not an absolute certainty. Experts have compared the case of Delhi with that of the Brazilian city of Manaus. A study carried out in Manaus using blood donors as samples indicated that about 76 per cent of the population of the city may well have been infected by the virus at some point. In keeping with this, the case count in the city was apparently kept relatively low for months before seeing a sharp resurgence in recent times. If this resurgence may be seen as a result of immunity fading over time, then it is reasonable to expect that the possible herd immunity in Delhi and elsewhere in India will also likewise fade. Much like vaccine immunity, natural immunity too fades with time. This is precisely why health experts still recommend those who have been vaccinated to carry on with masking, sanitising and social-distancing measures until the chain of infection is broken completely and the virus recedes. Then there is the fear of the new variants making such antibodies ineffective or at least less effective. Presently, several new variants of the Coronavirus are being reported across the world with health bodies reporting that the strains are possibly more infectious and even more deadly. As the global vaccination campaign will likely take quite some time, the likelihood of new variants emerging and starting new infection waves cannot be ruled out. Thus, it is too early for complacency and relief. Much like the rest of the world, India is not out of the figurative woods yet.