Around 89 percent of people who tested positive for Covid-19 in RT-PCR, and 26 percent who tested negative, developed antibodies against the virus, according to a study conducted by researchers in Bangladesh's Chattogram and USA.
Dr Abdur Rob, a senior consultant of medicine and head of Covid-19 ward in Chattogram General Hospital, was the principal investigator of the study, reports our Chattogram correspondent.
The study was conducted on 1,530 people -- 941 tested positive for Covid-19 and 589 tested negative.
Total 834 people among the 941 who tested positive for the virus, developed antibodies, putting the rate at 88.6%.
On the other hand, antibodies were found in 153 among 589 people who tested negative, putting the rate at 26%.
The samples were of those between the age group of 26 and 50 -- living in Chattogram region, said sources, adding that the samples were collected from the people between March and October last year.
The title of the study is "Seroprevalence of SARS-2 Covid-19 Antibody in Chattogram: A Cross-sectional Study" -- conducted between October last year and April this year.
A total of six researchers conducted the study for six months, Dr Abdur Rob said.
"The significance of the study is that we have found antibody against Covid-19 in people who tested negative for Covid-19 in RT-PCR and the number was not nominal," he said.
"We have found some other important things in the study...these are: many patients suffered from post-Covid-19 symptoms," he said, adding, "We have found that 23.8 percent Covid-19 patients suffered from cough and breathlessness days after recovery while 7.8 percent patients had heart attack or brain stroke."
"We have also found that 28.7 percent patients developed skin disease or loss of hair while 24.7 percent patients suffered from depression," said Dr Rob.
Dr Mohiuddin Ahmed Kabir Chowdhury, a research fellow at Arnold School of Public Health, University of South Carolina, USA; Dr Hamidullah Mehedi, junior consultant of medicine at Chattogram General Hospital; Dr Asif Khan, deputy civil surgeon of Chattogram; Dr Omee Dev and Dr Mortahina Rashid were the co-investigators of the study.