Madhya Pradesh has the highest Covid-19 seroprevalence among the states at 79%, while Kerala has the lowest (44.4%), according to the fourth countrywide serological survey conducted by the Indian Council of Medical Research.
Serological surveys reveal how many people have antibodies against an infection. The percentage of a population that have antibodies against an infectious agent is called seroprevalence, according to the United States Centers for Disease Control and Prevention.
However, it is still not clear how long antibodies last in an infected person and the levels required to prevent reinfection.
On Wednesday, the Centre released state-wise data from the serological survey conducted across 70 districts of the country. In Rajasthan, the seroprevalence was found to be 76.2%, followed by Bihar (75.9%), Gujarat (75.3%), Chhattisgarh (74.6%), Uttarakhand (73.1%), Uttar Pradesh (71%) and Andhra Pradesh (70.2%).
Haryana (60.1%), Maharashtra (58%) and Assam (50.3%) were among the states where the seroprevalence was low.
Despite reporting the lowest seroprevalence, Kerala has been registering a high number of daily Covid-19 cases.
On Wednesday, the state recorded 22,056 new infections, taking its tally to 33,27,301 since the pandemic broke out in January 2020. The state also accounted for more than 50% of all new infections in India on Tuesday.
Kerala’s positivity rate, which is the percentage of people who test positive for the coronavirus out of those who have been tested overall, rose to 11.2%.
Dr Anish, a member of Kerala’s Covid expert committee, said the state was 23 percentage points behind the threshold for herd immunity, ANI reported. “One way of protecting this 23% is massive vaccination at a very high rate as compared to other parts of India,” he told the news agency. “The Centre should give larger amount of vaccines to Kerala.”
Sero surveys in India
The fourth serological survey showed that 67.6% Indians above the age of six had antibodies against Covid-19. The findings were released by the Centre last week.
The Centre said the survey was designed to study the extent of the spread of Covid-19 at the national level. “The national sero-survey results do not reflect the heterogeneity of sero-prevalence between districts and even between States,” the government said.
It said that the states and Union territories should conduct surveys to obtain district-level data on seroprevalence, which will be essential in framing public health response measures at a local level.
The fourth survey had shown a steep increase in the presence of antibodies in the population as compared to the third one, which was conducted in December and January. At that time, 21.5% of the country’s population was estimated to have been exposed to the coronavirus.
The second survey was conducted between August 17 and September 22, 2020. It found that 6.6% of the participants had antibodies against the coronavirus. The first survey, conducted between May 11 and June 4, 2020, had found that only 0.73% of the population had been exposed to the virus.
India has recorded 3,15,28,114 Covid-19 cases since the pandemic broke out in January last year. As many as 4,22,662 patients have died of the infection in the country.