Past SARS-CoV-2 infection protection against re-infection: a systematic review and meta-analysis https://www.thelancet.com/journals/la…
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 infection caused by Alpha, beta, and delta variants
- Lower levels of protection from infection caused by Omicron BA.1 variant
- Effectiveness against re-infection with the omicron BA.1 variant
- Protection against reinfection, 45·3%
- Protection against omicron BA.1 symptomatic reinfection, 44%
- Protection against severe disease if reinfected with BA.1 is 88.9%
- Protection from re-infection with ancestral strains Alpha and delta variants Declined over time 78·6%
at 40 weeks Protection against re-infection with omicron BA.1
- Declined more rapidly 36·1% at 40 weeks
- Protection against severe disease at 40 weeks if reinfected
- Remained high for all variants 90·2% for alpha and delta variants 88·9% for omicron
BA.1 Data suggests that the level of protection afforded by previous infection is at least as high, if not higher than that provided by two-dose vaccination using high-quality mRNA vaccines
As of June 1, 2022 COVID-19 pandemic had caused an estimated
- 17·2 million total deaths
- 6·88 million reported deaths
- 7·63 billion total infections and re-infections.
Between 15th November 2021 and 1st June 2022 3·8 billion people 46% of the global population, have been infected by omicron and sub-lineages.
Understanding needed for
- Predicting future potential disease burden
- Designing policies, travel, access to venues
- Informing choices, vaccines
- Estimate protection from past infection
- Systematically synthesise studies 65 studies from 19 countries, By variant By time since infection Up to Sept 31, 2022
