A new study shows that people who previously had COVID-19 have an 88% lower risk of being hospitalized or dying than those who have never been infected. This is according to a review and analysis of previous studies on natural immunity against COVID-19 published in The Lancet.
Researchers found that the protection provided by natural immunity against reinfection, symptomatic disease, and severe illness is at least as good as that provided by two doses of the mRNA vaccines (Moderna, Pfizer-BioNTech) for ancestral, Alpha, Delta, and Omicron BA.1 variants. However, the study did not include data on infection from Omicron XBB and its sublineages.
The study reviewed 65 studies from 19 countries and found that protection against reinfection from a pre-Omicron variant was about 85% at one month and fell to about 79% at ten months. Protection against reinfection from a pre-Omicron variant was lower (74% at one month) and declined more rapidly to 36% at around ten months. However, the protection against severe illness remained high for ten months, with a 90% protection rate for ancestral, Alpha, and Delta variants and 88% for Omicron BA.
The researchers say that vaccination is still the safest way to acquire immunity, especially for those at high risk of severe illness, such as those over 60 years old and those with other health conditions.
Co-author Dr Caroline Stein said:
“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. 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.”
