Around 40 per cent of COVID-19 patients lost antibodies post their recovery from the disease, revealed a survey by the Ahmedabad civic body covering 1,800 previously infected people in the city.
The loss of antibodies makes people who have recovered from the disease susceptible to reinfection, said Dr Bhavin Solanki, medical officer of the Ahmedabad Municipal Corporation (AMC), on Friday.
The survey was conducted on 1,800 persons, who tested positive for coronavirus between March and July through antigen tests, said Dr Jay Sheth, associate professor of civic-run MET Medical College.
Developing antibodies means a person contracted COVID-19, recovered and subsequently developed them against the viral disease.
"The survey has revealed that around 40 per cent of the recovered patients have lost antibodies, and antibodies disappear from several people in the long run after recovery," Solanki said.
This suggests that people who have lost antibodies can contract COVID-19 again in the future, he said.
"Till a vaccine is made available in the market, we must take precautionary measures such as social distancing and wearing masks," Solanki said.
Voicing a similar concern, Dr Sheth said, "Absence of antibodies in 40 per cent of recovered persons suggests that they can get reinfected. A detailed study is required to analyse this phenomenon."
Epidemic expert Dr R K Patel called for a detailed research into the results of the civic survey.
"Coronavirus is a new subject for everyone. We still do not know how the virus behaves. It's a matter of research why antibodies disappear from recovered patients," said Dr Patel, director of U N Mehta Institute of Cardiology and Research Centre.
The best defence against the viral infection is to practise social distancing and wear masks, Dr said.
According to health experts, confirmed cases of reinfections have been reported in foreign countries.
Ahmedabad district has so far recorded 32,013 COVID-19 cases and 1,741 deaths.