Protection by vaccines and previous infection against the Omicron variant of SARS-CoV-2
Open accessPreprint — published as 10.1093/infdis/jiac161 · Paper page
Abstract
The Omicron variant of the SARS-CoV-2 virus carries mutations, which enable it to evade immunity conferred by vaccines and previous infections. We used a Cox proportional hazards model and a logistic regression model on individual-level data on all laboratory-confirmed SARS-CoV-2 infections in the Czech Republic to estimate the relative risk of infection, hospitalization, including severe states, for Delta and Omicron variants, adjusting for sex, age, previous infection, vaccine type and vaccination status. A recent (<2 months) two-dose vaccination reached VE 43% (95% CI: 42-44) against infection by Omicron compared to 73% (95% CI: 72-74) against Delta. A recent booster increased VE to 56% (95% CI: 55-56) against Omicron infection compared to 90% (95% CI: 90-91) for Delta. The VE against Omicron hospitalization of a recent two-dose vaccination was 45% (95% CI: 29-57), with a recent booster 87% (95% CI: 84-88). The VE against the need for oxygen therapy due to Omicron was 57% (95% CI: 32-72) for recent vaccination, 90% (95% CI: 87-92) for a recent booster. Post-infection protection against Omicron hospitalization declined from 68% (95% CI: 68-69) at <6 months to 13% (95% CI: 11-14) at >6 months after a previous infection. A recent combination of a previous infection and vaccination was more protective then either alone with a slight benefit from a vaccination preceding an infection. Once infected, the OR for Omicron relative to Delta was 0.36 (95% CI: 0.34-0.38) for hospitalization, 0.24 (95% CI: 0.22-0.26) for oxygen therapy, and 0.24 (95% CI: 0.21-0.28) for ICU admission. Significance Statement: A nation-wide study shows that the protection of a previous infection or vaccination is lower against Omicron compared to Delta variant of SARS-CoV-2 and further declines with time. A booster dose or a combination of post-infection immunity with a vaccine conferred significant benefit to individuals in the Omicron wave in the Czech Republic, which further strengthens the importance of vaccination as an effective public health measure.
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Consistent findings were reached, indicating rapid waning of vaccine protection against symptomatic Omicron infection, consistent with findings of other studies for effectiveness against Omicron infection (with no BA.1/BA.2 subvariant specified).
“Notwithstanding these limitations, consistent findings were reached, indicating rapid waning of vaccine protection against symptomatic Omicron infection that are consistent with findings of other studies for effectiveness against Omicron infection (with no BA.1/BA.2 subvariant specified)42–48.”
From Duration of mRNA vaccine protection against SARS-CoV-2 Omicron BA.1 and BA.2 subvariants in Qatar (2022) · cites this paper as [46]
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References 12 · Cited by 67
- Authors
- Šmíd, M., Berec, L., Májek, O., Pavlík, T., Jarkovský, J., Weiner, J., Přibylová, L., Barusová, T., & Trnka, J.
- Affiliations
- Czech Academy of Sciences (CZ)
- Masaryk University (CZ)
- Corresponding author
- Šmíd, Martin
- ORCID
- Venue
- The Journal of Infectious Diseases
- Publisher
- openRxiv
- Published
- 2022-02-25
- Volume
- 226
- Issue
- 8
- Pages
- 1385-1390
- ISSN
- 0022-1899 (ISSN-L)
- PMC
- PMC9129207
- OpenAlex
- W4225770995
- Cited by
- 67
- References
- 12
- Citations by year
- 2026: 1 · 2025: 6 · 2024: 13 · 2023: 20 · 2022: 27
- FWCI
- 8.05
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- The Journal of Infectious Diseases (publishedVersion)
- medRxiv (acceptedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
- Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
- Keywords
- Omicron variant, SARS-CoV-2, COVID-19 vaccines, vaccine effectiveness, booster vaccination, prior infection, post-infection immunity, hospitalization, oxygen therapy, intensive care unit admission, Delta variant, immune evasion
- MeSH terms
- COVID-19, SARS-CoV-2, Humans, Vaccination, Vaccines
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