People who have had 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 by British medical 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 nose and throat 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 a risk of getting an infection and passing it on to others.”
Major implications
Experts who were not directly involved in the research, known as the SIREN study, urged people to take note of its main findings.
“These data reinforce the message that, for now, everyone is a potential source of infection for others and should behave accordingly,” said Eleanor Riley, a professor of immunology and infectious diseases at the University of Edinburgh.
Simon Clarke, an associate professor of cellular microbiology at the University of Reading, said the study “has major implications for how we can get out of the current crisis.”
“This means that the vast majority of the population will either have to have natural immunity or be immunized for us to lift the restrictions on our lives, unless we are prepared to see that more people are infected and die because of it. COVID-19, ”he said.
PHE said in a statement that the study was not able to explore antibodies or other immune responses to COVID-19 vaccines that were launched in the UK. The effects of the vaccine will be studied as part of SIREN later this year, he said.
The SIREN study involves tens of thousands of healthcare workers in the UK who have been regularly tested since June for new COVID-19 infections, as well as the presence of antibodies.
Between June 18 and November 24, the scientists discovered 44 potential reinfections – two “probable” and 42 “possible” – among 6,614 participants who tested positive for antibodies. This represents a protection rate of 83% against reinfection, they said.
The researchers said they would continue to monitor participants to see if this natural immunity could last more than five months in some. But they said early evidence from the next stage of the study suggested that some people with immunity could still carry high levels of the virus.
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