A study has found that 54% of the people in Hyderabad have developed antibodies against coronavirus, which indicates prior exposure to the virus that causes COVID-19. A total of around 9,000 samples were collected from across Hyderabad as part of the survey. The survey was carried out in Hyderabad as part of a joint effort CSIR-Centre for Cellular and Molecular Biology (CCMB), Indian Council for Medical Research-National Institute of Nutrition (NIN) and Bharat Biotech.
Thirty wards were shortlisted for the survey and around 300 samples were collected from each ward. All the samples were collected from people older than 10 years of age. Interestingly, most wards showed a similar uniform range of seroprevalence, from 50-60%. Some wards also showed as much as 70% while some also showed as low as 30% as well. Seroprevalence refers to the number of individuals in a population who test positive for a disease, which is based on serology specimens.
The study revealed that women in Hyderabad have shown a marginally higher seropositivity rate of 56% than the men, who showed 53%. Those above the age of 70 showed a lower seropositivity rate of only 49%. This can also be because most of them have been extra cautious by staying at home with limited mobility.
Individuals who had COVID-19 cases in their own households showed a seropositivity rate of 78%.
Dr A Laxmaiah, a scientist at NIN, observed that having a larger number of rooms in houses and smaller family size were more likely to have a lower prevalence of coronavirus infection.
“This multistage random sampling study on 9,000 people in the city of Hyderabad showed that more than 75% of the seropositive population did not know that they had contracted coronavirus Infection in the past. This suggests seroconversion, that is, antibody formation has happened even with silent infections," said Dr R Hemalatha, Director, NIN.
Dr Rakesh Mishra, Director of CCMB felt that the population of Hyderabad is slowly heading towards herd immunity, which refers to a scenario where a section of the population develops indirect protection from a disease because of immunity developed through a previous infection or vaccination, thereby reducing infection among individuals who lack immunity.
Dr Rakesh said, “This study brings a comprehensive perspective of a potentially protective immune response against the coronavirus in the city’s population. The data indicates that the population of Hyderabad might be slowly moving towards herd immunity, which will be certainly accelerated by the ongoing vaccination effort.”