http://www.thelancet.com/article/S1473309922008015/pdf

Protective effectiveness of previous SARS-CoV-2 infection and hybrid immunity against the omicron variant and severe disease: a systematic review and meta-regression

http://www.thelancet.com/article/S1473309922005953/pdf

Risk of reinfection, vaccine protection, and severity of infection with the BA.5 omicron subvariant: a nation-wide population-based study in Denmark

The SARS-CoV-2 omicron BA.5 subvariant is progressively displacing earlier subvariants, BA.1 and BA.2, in many countries. One possible explanation is the ability of BA.5 to evade immune responses elicited by prior BA.1 and BA.2 infections. The impact of BA.1 infection on the risk of reinfection with BA.5 is a critical issue because adapted vaccines under current clinical development are based on BA.1. We used the national Portuguese COVID-19 registry to analyze the risk of BA.5 infection in individuals without a documented infection or previously infected during periods of distinct variants' predominance (Wuhan-Hu-1, alpha, delta, BA.1/BA.2). National predominance periods were established according to the national SARS-CoV-2 genetic surveillance data (when one variant represented >90% of the sample isolates). We found that prior SARS-CoV-2 infection reduced the risk for BA.5 infection. The protection effectiveness, related to the uninfected group, for a first infection with Wuhan-Hu-1 was 52.9% (95% CI, 51.9 - 53.9%), for Alpha 54.9% (51.2 - 58.3%), for Delta 62.3% (61.4 - 63.3%), and for BA.1/BA.2 80.0% (79.7 - 80.2%). The results ought to be interpreted in the context of breakthrough infections within a population with a very high vaccine coverage (>98% of the study population completed the primary vaccination series). In conclusion, infection with BA.1/BA.2 reduces the risk for breakthrough infections with BA.5 in a highly vaccinated population. This finding is critical to appraise the current epidemiological situation and the development of adapted vaccines.

/pdf/risk-of-ba-5-infection-in-individuals-exposed-to-prior-sars-1vrlqt16.pdf

Risk of BA.5 infection in individuals exposed to prior SARS-CoV-2 variants

Impact of National Omicron Outbreak at the end of 2022 on the future outlook of COVID-19 in China Liwei Zheng, Shuying Liu and Fengmin Lu Department of Microbiology & Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, People’s Republic of China; SL Consulting, Thousand Oaks, CA, USA; Beijing Key Laboratory of Hepatitis C and Immunotherapy for Liver Diseases, Peking University People’s Hospital, Peking University Hepatology Institute, Beijing, People’s Republic of China

https://doi.org/10.1080/22221751.2023.2191738

Impact of National Omicron Outbreak at the end of 2022 on the future outlook of COVID-19 in China

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9934854

COVID-19 infection, reinfection, and the transition to endemicity

https://doi.org/10.1016/s0140-6736(22)02465-5

Tom Pham

Papers

Past SARS-CoV-2 infection protection against re-infection: a systematic review and meta-analysis