A new study, doctors from the Icahn School of Medicine tested for antibodies in over 1,000 patients who had recovered from mild cases of COVID-19. On a first test, they found that 89% of them had antibodies. Two weeks later, they re-tested about two-thirds of the patients who had tested negative. With the additional time, 93% of those who had tested negative the first time showed antibodies. Combined, that means more than 99% of patients who came down with mild COVID-19 had antibodies within a month of showing symptoms.
This study adds to what we know already by being the largest study to date and focusing on people with only mild cases, who are the least likely to develop a strong antibody response. This New York Times article adds some color commentary from the authors and a Columbia virologist not involved in the study. Although this new study doesn’t prove that these antibodies confer immunity, or how long the antibodies will last, they say there’s strong reason to believe these people will be immune, at least for now.
You may be concerned that antibodies don’t actually make someone. There were stories from South Korea about recovered patients getting reinfected. But last week, doctors from the Korean CDC and Seoul National University said those patients only had dead virus circulating in their blood; they hadn’t been reinfected and weren’t infectious. Together, these results are great news for people who have recovered from COVID-19 and give us reason to be optimistic that SARS-CoV-2 vaccines can work.