LONDON (Reuters) – People with COVID-19 are very likely to have immunity to it for at least five months, but there is evidence that those with antibodies could still carry and spread the virus, a study conducted in the US Britain for health workers found.
Preliminary findings by Public Health England (PHE) scientists have shown that reinfections in people who have COVID-19 antibodies from a past infection are rare – only 44 cases were found in 6,614 previously infected people in the study.
But experts have warned that the results mean that people who contracted the disease in the first wave of the pandemic in the first months of 2020 may now be vulnerable to catching it again.
They also warned that people with so-called “natural immunity” – acquired through infection – could still carry the SARS-CoV-2 coronavirus in their noses and throats and could inadvertently transmit it.
“We now know that most people who have had the virus and developed antibodies are protected from reinfection, but this is not complete and we do not yet know how long the protection will last,” said Susan Hopkins, PHE senior medical advisor and co-leader of the study. , whose conclusions were published on Thursday.
“This means that even if you think you already have the disease and are protected, you can rest assured that it is very unlikely that you will develop severe infections. But there is still the risk of getting an infection and passing it on to others. ”
A study statement says its findings do not address antibodies or other immune responses to vaccines that are now being launched against COVID-19 or on vaccine efficacy. Vaccine responses will be considered later this year, he said.
The research, known as the SIREN study, involves tens of thousands of UK healthcare workers who have been tested regularly since June for new COVID-19 infections, as well as the presence of antibodies.
Between June 18 and November 24, scientists detected 44 potential reinfections – two “likely” and 42 “possible” – out of 6,614 participants who tested positive for antibodies. This represents a protection rate of 83% against reinfection, they said.
The researchers plan to further monitor and evaluate participants to see if this natural immunity can last more than five months in some. But they warned that early evidence from the next stage of the study already suggests that some people with immunity may still carry high levels of the virus and may pass it on to others.
“Therefore, it is crucial that everyone follows the rules and stays at home, even if they have previously had COVID-19,” they said in a statement on their results.
Reporting by Kate Kelland; Montage by Mark Heinrich