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People who have already contracted the coronavirus are as protected against reinfection as those who have received the best Covid-19 vaccines, according to a survey of 20,000 UK healthcare workers, the largest study in the world so far.
Public Health England regularly screened two groups of volunteers paired between June and November: 6,000 healthcare 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 a previous infection provided at least 83 percent protection against reinfection. It provided more than 94 percent protection against symptomatic Covid-19, matching the numbers for the most effective Covid-19 vaccines.
Susan Hopkins, PHE Senior Medical Advisor, said she was “very encouraged” by the finding that the infection provided powerful, if not complete, protection against re-infection for at least five months.
“Natural infection looks as good as a vaccine, which is very good news for the population,” he said.
Although the study was unable to provide data on possible protection beyond five months, Professor 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. past.
“It will give a level of immunity in the community that will reduce transmission,” he said.
During the study, 44 people in the previously infected group of 6,000 tested positive at least three months apart, suggesting they had been “potentially reinfected.” But because genomic analysis was not available to confirm that different viruses were responsible for the two infections, proven reinfections were not considered. The same virus could have been incubated for a long period in the same individual, although the researchers thought this was less likely in most cases.
Eleanor Riley, a professor of virology at the University of Edinburgh, said the study data also suggested that people who had recovered from Covid-19 were less likely to transmit the virus to others without knowing it, because natural infection seemed to provide about 75% protection against asymptomatic reinfection. “This is good news in terms of the long-term trends of the pandemic,” he said.
Still, Professor Hopkins urged people “not to misinterpret these early findings.”
“If you think you already had the disease and are protected, you can be sure that it is very unlikely that you will develop a serious infection, but there is still a risk of contracting an infection and transmitting it to other people,” he said.
The cut-off point for the preliminary analysis in late November came too early for researchers to investigate how well the vaccines, the first of which was approved for use in the UK in December, protected healthcare workers. in the study group.
The researchers were also unable to assess the impact of the newer and more contagious variant B.1.1.7 on reinfection rates. PHE aims to expand the research project over the next three months to include 100,000 healthcare workers and consider both issues.
