Protection afforded by prior infection against SARS-CoV-2 reinfection with the Omicron variant

medRxiv Jan 6, 2022
https://www.medrxiv.org/content/10.1101/2022.01.05.22268782v1

BACKGROUND: Natural SARS-CoV-2 infection elicits strong protection against reinfection with the Alpha (B.1.1.7), Beta (B.1.351), and Delta (B.1.617.2) variants. However, the Omicron (B.1.1.529) variant harbors multiple mutations that can mediate immune evasion. We estimated effectiveness of prior infection in preventing reinfection (PES) with Omicron and other SARS-CoV-2 variants in Qatar.

HIGHLIGHTS
- Protection afforded by prior infection in preventing symptomatic reinfection with Alpha, Beta, or Delta is robust, at about 90%.**
- While such protection against reinfection with Omicron is lower, it is still considerable at nearly 60%.**
- Prior-infection protection against hospitalization or death at reinfection appears robust, regardless of variant.**

Although this study is not a head to head comparison of natural immunity versus vaccine induced immunity, it does suggest that protection afforded by natural infection is superior to vaccine induced immunity.

January 10, 2022