Hiam Chemaitelly et al.

The future of the SARS-CoV-2 pandemic hinges on virus evolution and duration of immune protection of natural infection against reinfection. We investigated duration of protection afforded by natural infection, the effect of viral immune evasion on duration of protection, and protection against severe reinfection, in Qatar, between February 28, 2020 and June 5, 2022.

… We sought to answer three questions of relevance to the future of this pandemic: 1) When infected with a pre-Omicron variant, how long does protection persist against reinfection with pre-Omicron variants? 2) When infected with a pre-Omicron variant, how long does protection persist against reinfection with an Omicron subvariant? 3) When infected with any variant, how long does protection persist against severe, critical, or fatal COVID-19?

… These analyses were implemented using Qatar’s total population with large sample sizes, thus minimizing the likelihood of bias.

In conclusion, protection of natural infection against reinfection wanes and may diminish within a few years. Omicron immune evasion accelerates this waning. Meanwhile, protection against severe reinfection is very strong with no evidence for waning, regardless of variant, for over 14 months after the primary infection.