Anyone who has survived an infection with the coronavirus SARS-CoV-2 is usually well protected from a serious illness with hospitalization or death after 40 weeks. This applies to all virus strains, but the probability of new infection with the variant Omikron BA.1 is significantly higher than with the older virus types, according to the result of a meta-analysis in the journal «The Lancet».
Background
The measures necessary and useful to contain the COVID-19 pandemic also depend on the extent to which previous infections protect against new infections, diseases and deaths.
Design
Systematic review and meta-analysis to estimate the protective effect of previous SARS-CoV-2 infections depending on virus variants and elapsed time.
Results
- The researchers found 65 studies from 19 countries.These generally demonstrate a «high» protection from previous infections and symptomatic diseases for the wild type as well as the variants alpha, beta and delta. «Substantially lower», however, was the protection after infection with the Omikron BA.1 variant.
- The pooled data show protection against new infections of 45.3% (95% confidence interval 17.3 – 76.1) and protection against symptomatic diseases of 44.0% (95% CI 26.5 – 65.0) for the Omikron BA.1 variant.
- Protection against serious illness (hospitalisation and death) was above 78% for all variants, including Omikron BA.1.
- Over time, protection against re-infection decreased, but remained high at week 40 at 78.6% (95% CI 49.8 – 93.6) for all variants except Omikron. Here, the protection was estimated at 36.1% (95% CI 24.4 – 51.3).
- Protection against severe disease was again good for all variants and was 90.2% for wild-type, alpha, and delta (95% CI 69.7-97.5); for Omikron BA.1 88.9% (95% CI 84.7 – 90.9).
Clinical significance
The protective effect after natural infection with one of the SARS-CoV-2 variants is less than 50% for new infection.Although protection against a new infection with the variant Omikron BA1 is lost faster than against the other virus strains, a previous infection protects against a serious illness with approximately 90% regardless of the variant very well.
Funding: Bill & Melinda Gates Foundation, J Stanton, T Gillespie, and J and E Nordstrom.
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Source — https://www.univadis.de/viewarticle/sars-cov-2-infektion-sch%25C3%25BCtzt-fast-ein-jahr-vor-schwerer-2023a10004nw