Second Sero Survey in Ahmedabad: No herd immunity yet, 40% of Covid-19 recovered patients lack antibodies

Samples for the survey were collected from different wards keeping in mind the proportion of the population and varied age groups.

In a troubling development, the sero survey conducted in Ahmedabad has found that 40 per cent of recovered Covid-19 patients have no presence of antibodies against the coronavirus. With 40 per cent of the patients, despite having recovered from the virus, remaining vulnerable to re-infection the finding could sound the death knell for experts who were rooting for herd immunity as a possible solution to the deadly pandemic. The sero survey conducted in the city also suggested that about 23.24 per cent of the residents of the city have contracted the virus, which is up by 5.63 per cent from the last Sero survey conducted in the month of June, according to an Indian Express report. While the latest survey collected samples from about 10,310 people spread evenly across the city and from various age groups, the survey conducted in the month of June had a larger base of about 30000 samples.

Noting that only 60 per cent of those who had recovered from the disease are left with the antibodies, Dr Bhavin Solanki, incharge Medical Officer of Health, AMC told The Indian Express that people who have recovered from the disease are still susceptible to get re-infected. He also said that the response to the Coronavirus pandemic cannot rely on such low levels of immunity even among those who have recovered from the disease. He further said that till the time the country gets an effective Covid-19 vaccine, the response against Coronavirus should rely on proven preventive measures such as face mask and other social distancing measures. However, he insisted that more research and studies should be conducted on the issue of loss of immunity among those who have recovered from the disease.

The latest sero survey was conducted from August 15 to August 30 in the city. Samples for the survey were collected from different wards keeping in mind the proportion of the population and varied age groups. The survey also found that the presence of antibodies was higher among women at 25.37 per cent in comparison to 21.81 per cent among the men. The sero positivity rate was also not very high among health workers who were part of the survey as only 404 of them had antibodies against the virus from a total sample of 1,708 workers. The survey also found that antibodies were present in about 31.92 people who were among the direct contacts of confirmed cases. A total of 3,973 samples were collected from people who were in direct contact with the confirmed cases of the disease out of which 1,268 showed the presence of antibodies.