Overall, 194 of 3,248 participants (6%) had detectable antibodies to SARS-CoV-2 the first time they were tested. In this group, 94% saw a decline in their antibody levels, with 28% not producing enough Covid-19 antibodies to meet a clear threshold that would suggest prior infection. Most people infected with the virus develop antibodies over the next several weeks, but people with milder or asymptomatic infection develop fewer antibodies. Apart from helping to quantify how many infections seroprevalence studies may be missing, the results "challenge the notion of using serologic testing results at an individual level to designate previous SARS-CoV-2 infection," said the authors. Finally, the study also shows that the window is limited for collecting potentially effective "convalescent plasma" from the blood of patients who have fought off Covid-19, they added.

Source: Dhaka Tribune November 26, 2020 08:25 UTC