Past SARS-CoV-2 infection protection against re-infection: a systematic review and meta-analysis https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(22)02465-5/fulltext Group 1 Past SARS-CoV-2 infection Group 2 No past SARS-CoV-2 infection Effectiveness of past infection by outcome Infection Symptomatic disease Severe disease Findings High levels of protection from…