Over half of the Hyderabad population has developed antibodies against SARS-CoV-2, a seroprevalence study by the Centre for Cellular and Molecular Biology and National Institute of Nutrition in collaboration with Bharat Biotech has revealed.
The estimate is based on a multistage random sampling study conducted on 9,000 people in the city.
Dr Rakesh Mishra, director of CCMB said the “data is indicative that Hyderabad population might be slowly moving towards herd immunity, which will be certainly accelerated by the ongoing vaccination drive.”
Around 54% of Hyderabadis show antibodies against SARS-CoV-2, indicating prior exposure to the coronavirus, the scientists from the three Hyderabad-based organizations said on Thursday.
The researchers have checked for antibodies against the virus in people living in 30 wards out of 150 municipal wards in the Hyderabad corporation.
Three hundred people, from each ward, all of them older than 10 years of age, were tested. Most of the wards showed a similarly uniform range of seroprevalence, from 50-60%. However, a few wards showed as high as 70% while some are as low as 30%.
“Our study shows 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.
According to the collaborative study, individuals who suffered from prominent Covid-19 symptoms, as well as those who were asymptomatic, had an equivalent seroprevalence of around 54%.
18% of the study group had been tested earlier and found positive for the coronavirus. 90% of them were found to be seropositive, suggesting that they retained the antibody response.
Other findings
Women developed a marginally higher seropositivity rate of 56% than men (53 %).
Persons above 70 years of age showed lower seropositivity (49 %), “perhaps because of limited mobility and extra precautions taken during the pandemic".
Families with positive cases in their households showed the maximum seropositivity of 78%, followed by those with known Covid-19 contacts outside their household (68 %).
Dr A Laxmaiah, a scientist from NIN observed that households with a larger number of rooms and smaller family size resulted in a low prevalence of coronavirus infection.
Meanwhile, the total number of positive cases in Telangana inched closer to the three-lakh mark. On Thursday morning, the state health department has reported a cumulative 2,99,406 cases, including 152 cases added on Wednesday. While active cases are 1948, 835 persons are kept in-home or institutional isolation.