Previous COVID-19 infection provides strong and long-lasting protection against severe disease, according to a new study.
The research, published Thursday in the journal The Lancet, reviewed 65 studies on natural immunity to find that the average effectiveness was at least 88% against hospitalization and death for all coronavirus variants 10 months after infection. The research did not include omicron subvariant XBB.1.5, which is dominant in the U.S.
But natural immunity provided substantially reduced protection against symptomatic infection against omicron subvariant BA.1 at 10 months, mounting about a 36% efficacy.
The researchers emphasized that the data should not be used to discourage vaccination, which they said in a better way to acquire protection against COVID-19.
“ Vaccination is the safest way to acquire immunity, whereas acquiring natural immunity must be weighed against the risks of severe illness and death associated with the initial infection,” lead author Stephen Lim from the Institute for Health Metrics and Evaluation at the University of Washington’s School of Medicine said in a statement.
The authors suggested that the data could be used for guidance on when individuals should get vaccinated.
"Vaccines continue to be important for everyone in order to protect high-risk populations such as those who are over 60 years of age and those with comorbidities”, study author Caroline Stein said in a statement. “This also includes populations that have not previously been infected and unvaccinated groups, as well as those who were infected or received their last vaccine dose more than six months ago. Decision makers should take both natural immunity and vaccination status into consideration to obtain a full picture of an individual’s immunity profile”.
A recent study led by the World Health Organization found that hybrid immunity – the mix of protection provided by COVID-19 vaccination as well as infection – offers the highest level of protection. It was 97% effective at preventing hospitalization and severe COVID-19 among fully vaccinated individuals a year after their most recent infection or vaccination.
It also found that for those with previous infection and no vaccinations, effectiveness against hospitalization and severe disease was nearly 75% a year out, while protection against infection was less than 25%.
“The analysis shows that hybrid immunity provides higher protection, demonstrating the advantages of vaccination even after people have had COVID-19” ,WHO said in a statement.
The CDC this week published what it characterized as the first estimate of the updated booster shot’s efficacy against symptomatic infection with XBB.1.5, finding that the shots are at least 40% effective against symptomatic illness from omicron subvariants XBB.1.5 and XBB among fully vaccinated adults within three months of the shot’s administration.
“Findings from this analysis of national pharmacy testing data show that a bivalent mRNA booster dose provided added protection against symptomatic XBB/XBB.1.5 infection for at least the first 3 months after vaccination in persons who had previously received 2, 3, or 4 monovalent vaccine doses,” the authors wrote. “All persons should stay up to date with recommended COVID-19 vaccines, including receiving a bivalent booster dose when eligible”.
While vaccines still appear to work against the new variant, Evusheld does not, prompting the Food and Drug Administration on Thursday to pull its emergency use authorization. Evusheld is an antibody treatment that was used as a pre-exposure treatment for people at high risk for severe COVID-19, like those with compromised immune systems.
The development was not a surprise considering the FDA earlier this month warned that it did not expect Evusheld to work on XBB.1.5.
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