People who have had COVID-19 will most likely have immunity to it for at least five months, but there is some evidence that people with antibodies may still be able to carry and spread the virus, a study of UK health professionals found.
Preliminary findings from Public Health England (PHE) scientists showed that re-infections in humans with COVID-19 antibodies from a previous infection are rare – with only 44 cases found among 6,614 previously infected people in the study.
But experts warned that the findings mean that people who contracted the disease during the first wave of the pandemic in the early months of 2020 may now be vulnerable to re-shelter.
They also warned that people with so-called natural immunity – acquired from having the infection – can still carry the SARS-CoV-2 coronavirus in their nose and throat and pass it on unknowingly.
“We now know that most of those who have had the virus and developed antibodies are protected against reinfection, but this is not complete and we do not yet know how long the protection lasts,” said Susan Hopkins, senior medical advisor at PHE and co-leader of the study, the findings of which were published Thursday.
This means that even if you think you have already had the disease and are protected, you can be sure that you are very unlikely to develop serious infections. But there is still a risk of catching an infection and (these) transfers to others. “
Big implications
Experts not directly involved in the study, known as the SIREN study, urged people to note the key findings.
“These data reinforce the message that everyone is a potential source of infection to others for the time being and should act accordingly,” said Eleanor Riley, professor of immunology and infectious diseases at the University of Edinburgh.
Simon Clarke, associate professor of cellular microbiology at the University of Reading, said the study “has big implications for how to 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 to fully lift the restrictions on our lives, unless we are willing to see many more people become infected and die from COVID-19,” ” he said.
PHE said in a statement that the study had been unable to investigate antibodies or other immune responses to the COVID-19 vaccines being rolled out in Britain. The vaccine effects would be studied as part of SIREN later this year, it said.
The SIREN study involves tens of thousands of health workers in the UK who have been regularly tested for new COVID-19 infections and for the presence of antibodies since June.
Between June 18 and November 24, scientists found 44 possible re-infections – two “probable” and 42 “possible” – among 6,614 participants who tested positive for antibodies. This represents an 83% protection rate against reinfection, they said.
The researchers said they would continue to monitor the participants to see if this natural immunity could last longer than five months in some cases. But they said early evidence from the next phase of the study suggested some people with immunity might still be able to carry high levels of viruses.
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