[ad_1]
People who recover from the coronavirus have a similar level of protection against future infections as those who receive a Covid vaccine, at least for the first five months, research suggests.
A Public Health England (PHE) study of more than 20,000 healthcare workers found that immunity acquired from a previous Covid infection provided 83% protection against re-infection for at least 20 weeks.
The findings show that while people are unlikely to be re-infected soon after their first infection, it is possible to contract the virus again and pass it on to other people.
“Overall, I think it’s good news,” said Professor Susan Hopkins, PHE senior medical advisor. “It allows people to feel that a previous infection will protect them from future infections, but at the same time it is not complete protection and therefore they should be careful when they are away from home. “
PHE recruited healthcare workers from hospitals across the UK and divided them into two groups: those with coronavirus before and those without. Between June and November last year, participants underwent biweekly PCR tests for the virus and monthly tests to examine antibody levels in their blood.
Over the five months, the researchers monitored the infection rates in the two groups. They detected 44 potential reinfections, including 13 symptomatic, among the 6,614 believed to have had Covid before, and 318 cases among the 14,173 who had no evidence of past infection. A previous infection, they conclude, provides 94% protection against symptomatic reinfection and 75% protection against asymptomatic reinfection.
The cases are known as “potential” reinfections because a detailed genetic analysis of the first and second viruses must be performed to confirm a reinfection, but information on the first infections was often not available.
“The immunity gives it a similar effect to the Pfizer vaccine and a much better effect than the AstraZeneca vaccine and that is reassuring for people. But we still see people who can transmit, so we want to take a note of caution, ”said Professor Hopkins. In clinical trials, two doses of Pfizer vaccine were 95% effective, compared with 62% for two doses of Oxford / AstraZeneca vaccine.
While the study is encouraging, it is unclear whether the same protection applies to older people. The study participants were between the ages of 35 and 54 and were expected to have robust immune systems. Older people tend to have weaker immune responses that are shorter.
Another question mark looms over the risk of reinfection from new Covid variants detected in the UK, South Africa and Brazil, a topic that PHE will investigate as the study continues this year.
“Do you think of numbers as a ‘glass half full or half empty?’ question, ”said Danny Altmann, professor of immunology at Imperial College. “For many, it may be disappointing to put hard numbers on the idea that immunity to this virus is apparently so variable and weak that there is a greater than 1 in 10 chance of reinfection, even at five months, much less now. , when many UK health workers are more than nine months out of first wave infections ”
