People who have already contracted coronavirus are as protected from re-infection as those who have received the best Covid-19 vaccines, according to a survey of 20,000 UK health workers, the largest study to date in the world.
Between June and November, Public Health England regularly tested two similar groups of volunteers – 6,000 health workers who had previously been infected with coronavirus and 14,000 who had not.
A comparison of infections in the two groups, described in preliminary results released Thursday, found that previous infections provided at least 83 percent protection against reinfection. This gave better than 94 percent protection against symptomatic Covid-19, which is consistent with the figures for the most effective Covid-19 vaccines.
Susan Hopkins, senior medical adviser at PHE, said she was “strongly encouraged” by the finding that infection has provided effective (though not complete) protection against reinfection for at least five months.
“Natural infection looks as good as a vaccine, which is very good news for the population,” she said.
Although the study could not provide more than five months of information on possible protection, Prof Hopkins was optimistic that it would ‘last much longer than the few months people speculated about’ during the early stages of the pandemic last year.
“It will give some immunity in the community that will reduce the transmission,” she said.
During the study, 44 people in the previously infected group tested 6,000 positive with at least three months apart, indicating that they were “possibly re-infected”. However, because genomic analysis was not available to confirm that different viruses were responsible for the two infections, they are not considered proven reinfections. The same virus could be incubated for a long period of time within the same individual, although the researchers thought it was less likely in most cases.
Eleanor Riley, a professor of virology at the University of Edinburgh, said the study’s data also suggested that people who recovered from Covid-19 were less likely to unknowingly transmit the virus to others because it appears to be natural. infection provides about 75 percent protection against asymptomatic reinfection. “This is good news in terms of the long-term trends of the pandemic,” she said.
Prof Hopkins still urged people not to misunderstand these early findings.
“If you believe you have had the disease and are protected, you can rest assured that you are highly unlikely to contract a serious infection, but there is still a risk that you could contract an infection and transmit it to others. , “she said.
The cut-off point for the preliminary analysis at the end of November came too early for the researchers to investigate how vaccines – the first of which were approved for use in the UK in December – protect health workers in the study group.
The researchers were also unable to determine the impact of the new and more contagious B.1.1.7 variant on the rate of reinfection. PHE aims to expand the research project to 100,000 health workers over the next three months and is considering both questions.