Could India achieve herd immunity for COVID-19 much before a vaccine is developed? This tantalising prospect is once again being discussed after data released by a private lab suggested that 18 crore Indians may already have developed antibodies against the novel coronavirus.
Theoretically, this means that they will develop immunity against further infection from the virus at least for a few months. How long the immunity exactly lasts is not clear since COVID-19 is a new disease, but past experience with viruses and scientific literature of several decade tells us that there will be a natural resistance to getting infected a second time.
Meanwhile, a serological survey conducted in the national capital has shown that 23.5 per cent of those surveyed had developed Immunoglobulin G antibodies, suggesting they had already been exposed to the novel coronavirus.
Extrapolating these results to Delhi’s entire population indicates that nearly one in every four Delhites may have developed some level of immunity to the virus, which has claimed more than 28,000 lives in the country.
So what does this all add up to?
The pan-India data is based on 60,000 antibody tests conducted by the private lab Thyrocare across 600 different geographical locations in a 20-day period.
The lab says that based on the data about 15 per cent of the country’s population has developed antibodies against the coronavirus, considering an error margin of 3 per cent.
Bhiwandi in Maharashtra’s Thane was deemed to be the area with the highest positivity rate in the county at 44 per cent. Peenya Dasarahalli (Bengaluru), Anand Vihar (New Delhi) and Hyderabad Jubilee area were some of the other pin codes in the country with very high positivity rates, according to the data.
Many caveats are in order here, though. Thyrocare’s data has not been peer-reviewed and, in fact, it has not even been published in any journal. Also, the lab carried out these tests simply because they were demanded by individuals, corporates or housing societies.
So it is at best a very rough map of the prevalence of COVID-19 in predominantly urban pockets. But taken together with a study conducted by the Indian Council of Medical Research (ICMR) last month (results of which have not been made public) and the new report on Delhi released on Tuesday, the figure of 18 crore Indians having been infected with COVID-19, many of whom may be asymptomatic, is believable. Still, it must be stressed that there is no official word on a pan-India figure yet.
Herd immunity in the absence of a vaccine is a controversial issue. Two countries that have come closest to following such a policy are Sweden and the UK. While the Boris Johnson government quickly dissociated itself from allegations that it was considering herd immunity to tackle COVID-19 after cases started to rise rapidly in March and April – the UK went into a thorough lockdown eventually -- the Swedish government has followed what can be best described as a deliberate policy of partial herd immunity.
The results have been depressing, and Sweden has reported a much higher fatality rate due to COVID-19 compared to its Nordic neighbours like Denmark and Norway.
India, of course, had one of the most stringent lockdowns anywhere in the world when it was first announced. But for whatever reasons, the virus has spread, much more than some officials may like to perhaps admit. Looking at the data, some independent experts are calling the government to open up colleges across the country so that the virus is allowed to spread quickly among younger people who are unlikely to fall very sick. In this way, they argue, the country could move faster towards the threshold of 40 to 50 per cent infection, which will then lead to the much-touted herd immunity.
But many experts disagree. With the joint family system quite common in India, the possibility of young people infecting their parents and grandparents can’t be ruled out, which could lead to hospitalizations and the death toll spiralling out of control.
Also, the disease does not always spare the young and an