In a new study, researchers found that people who have previously had COVID-19 are highly unlikely to contract the illness again, for at least six months following their first infection.
The research was conducted by a team at the University of Oxford and elsewhere.
Despite an estimated 51 million people infected with the virus worldwide, with high levels of transmission ongoing, reports of patients becoming re-infected after already having had COVID-19 are rare.
However, up until now, there have not been any large-scale studies of how much protection from re-infection people get after COVID-19.
The current study covered a 30-week period (April—November 2020) with 12,180 health care workers at Oxford University Hospital.
The healthcare workers were tested for antibodies to the virus that causes COVID-19 as a way of detecting who had been infected before.
The hospital tested staff regularly for COVID-19, both when they became unwell with symptoms and also as part of regular testing of well staff.
The researchers then followed whether staff who had been infected before had the same number of new COVID-19 infections as those who had not been infected before.
The team found during the study, 89 of 11,052 staff without antibodies developed a new infection with symptoms. None of the 1246 staff with antibodies developed a symptomatic infection.
Staff with antibodies were also less likely to test positive for COVID-19 without symptoms, 76 staff without antibodies tested positive compared to just three with antibodies.
The three healthcare workers with antibodies who tested positive for the virus that causes COVID-19 were all well and did not develop symptoms of COVID-19 again.
This suggests that most people are unlikely to get COVID-19 again if they have already had it in the previous six months.
Additionally, the opposite also proved true—health care workers who did not have antibodies against COVID-19 were more likely to develop the infection.
The findings show that being infected with COVID-19 does offer protection against re-infection for most people for at least six months.
The team says this is really good news because at least in the short term, most people who get COVID-19 won’t get it again.
One author of the study is Professor David Eyre.
The study is published here.
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