Systematic review of 65 studies from 19 countries: past infection gave strong, durable protection against severe disease, while protection against omicron BA.1 reinfection waned (45.3%, falling to 36.1% at 40 weeks). The authors state vaccination remains the safest way to acquire immunity.
protection from past infection against severe disease remained high for all variants studied (90.2% for ancestral, alpha, and delta variants and 88.9% for omicron BA.1 at 40 weeks)
Lancet 2023;401:833-842 (abstract)
Systematic review of 65 studies from 19 countries: past infection gave strong, durable protection against severe disease, while protection against omicron BA.1 reinfection waned (45.3%, falling to 36.1% at 40 weeks). The authors state vaccination remains the safest way to acquire immunity. Supports durable natural protection while also supporting hybrid/vaccine immunity — both sides must be read together.