26pc developed antibody without testing Covid-19 positive in Ctg: researchers

Around 89 percent of people who tested positive for Covid-19 in RT-PCR tests, and 26 percent who tested negative in Chattogram, developed antibodies against the virus, according to a study conducted by researchers in the port city.

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.

The study was conducted on 1,530 people -- 941 tested positive for Covid-19 and 589 tested negative.

A total of 834 people among the 941 who tested positive developed antibodies, putting the rate at 88.6 percent while antibodies were found in 153 among 589 people who tested negative, putting the rate at 26 percent.

The samples were of those between the age group of 26 and 50 -- living in Chattogram region. The samples were collected 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.

Six researchers conducted the study for six months, said Dr Abdur Rob.

"The significance of the study is that we have found antibody in people who tested negative in RT-PCR and the number was not nominal," he said.

"We have found some other important things in the study such as many patients suffered from post-Covid symptoms. We have found that 23.8 percent patients suffered from cough and breathlessness days after recovery while 7.8 percent patients had heart attack or brain stroke," he said.

"We also found that 28.7 percent patients developed skin disease or loss of hair while 24.7 percent 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.

Prof Dr Shakeel Ahmed, a public health expert and head of Bangladesh Institute of Tropical and Infectious Diseases laboratory, hailed the study.

Asked how people who tested negative developed antibody, he said although they tested negative for Covid-19, they got exposed to the virus but did not show symptoms. "We call it subclinical infection or call them asymptomatic patients," he said.

"Suppose someone from a four-member family tested positive for Covid-19 with symptoms. There is a high chance for three other members to get exposed to the virus. But none of them shows symptoms as their body instantly developed antibody. If those people go for testing after 14 days, they would test negative but actually they got infected and their body developed antibody against the virus."