Hybrid Immunity Provides Better Protection Against Omicron Variant

In a systematic review and meta-regression published in The Lancet Infectious Diseases, researchers determined that hybrid protection — the combination of SARS-CoV-2 infection and vaccination — provided better protection against Omicron variants than those protected by infection alone. The study compared the immunological protection of vaccination to illness, expanding on the current understanding of immunity and protection.

In this study, researchers looked at cohorts, cross-sectional, and case-control studies from multiple databases between January 1, 2020, and June 1, 2022. After using exclusionary criteria, the investigators focused on 26 studies; 11 reported on immunity from a previous SARS-CoV-2 infection, and 15 reported on hybrid immunity.

According to the study, a previous infection was 74.6% effective at preventing hospital admission or severe illness within one year. After one year, protection reduced significantly, only preventing re-infection in 24.7% of patients.

Comparatively, hybrid immunity was more remarkable, with 97.4% of participants avoiding hospitalization or severe infection within the first year of the primary vaccination series. While protection against reinfection waned in this group, it was still significantly higher than the infection-only group, at 41.8%.

Additionally, immunity against hospital admission or severe disease was 95.3% at six months for patients who received a booster after infection. Protection against reinfection was 46.5%.

Overall, these results imply that hybrid immunity yielded the best outcomes regarding immunity. Researchers in the publication concluded, “All estimates of protection waned within months against reinfection but remained high and sustained for hospital admission or severe disease. Individuals with hybrid immunity had the highest magnitude and durability of protection and, as a result, might be able to extend the period before booster vaccinations are needed compared to individuals who have never been infected.”

They suggest that future studies analyze waning immunity over a more extended period and consider new variants as they arise. Furthermore, the investigators urge policymakers to consider the benefits and efficacy of vaccination in improving immunity when making regulatory decisions.