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Protection Conferred by COVID-19 Vaccination, Prior SARS-CoV-2 Infection, or Hybrid Immunity Against Omicron-Associated Severe Outcomes Among Community-Dwelling Adults
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Clinical Infectious Diseases
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2023-11-24
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78
Publication Issue
5
Publication Begin
1372
Publication End
1382
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ciad716.pdf
Adobe PDF, 959.47 KB
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Abstract
Introduction: We assessed protection from coronavirus disease 2019 (COVID-19) vaccines and/or prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection against Omicron-associated severe outcomes during successive sublineage-predominant periods.
Methods: We used a test-negative design to estimate protection by vaccines and/or prior infection against hospitalization/death among community-dwelling, polymerase chain reaction (PCR)-tested adults aged ≥50 years in Ontario, Canada, between 2 January 2022 and 30 June 2023. Multivariable logistic regression was used to estimate the relative change in the odds of hospitalization/death with each vaccine dose (2-5) and/or prior PCR-confirmed SARS-CoV-2 infection (compared with unvaccinated, uninfected subjects) up to 15 months since the last vaccination or infection.
Results: We included 18 526 cases with Omicron-associated severe outcomes and 90 778 test-negative controls. Vaccine protection was high during BA.1/BA.2 predominance but was generally <50% during periods of BA.4/BA.5 and BQ/XBB predominance without boosters. A third/fourth dose transiently increased protection during BA.4/BA.5 predominance (third-dose, 6-month: 68%, 95% confidence interval [CI] 63%-72%; fourth-dose, 6-month: 80%, 95% CI 77%-83%) but was lower and waned quickly during BQ/XBB predominance (third-dose, 6-month: 59%, 95% CI 48%-67%; 12-month: 49%, 95% CI 41%-56%; fourth-dose, 6-month: 62%, 95% CI 56%-68%, 12-months: 51%, 95% CI 41%-56%). Hybrid immunity conferred nearly 90% protection throughout BA.1/BA.2 and BA.4/BA.5 predominance but was reduced during BQ/XBB predominance (third-dose, 6-month: 60%, 95% CI 36%-75%; fourth-dose, 6-month: 63%, 95% CI 42%-76%). Protection was restored with a fifth dose (bivalent; 6-month: 91%, 95% CI 79%-96%). Prior infection alone did not confer lasting protection.
Conclusions: Protection from COVID-19 vaccines and/or prior SARS-CoV-2 infections against severe outcomes is reduced when immune-evasive variants/subvariants emerge and may also wane over time. Our findings support a variant-adapted booster vaccination strategy with periodic review.
Citation
Lee N, Nguyen L, Austin PC, Brown KA, Grewal R, Buchan SA, Nasreen S, Gubbay J, Schwartz KL, Tadrous M, Wilson K, Wilson SE, Kwong JC. Protection Conferred by COVID-19 Vaccination, Prior SARS-CoV-2 Infection, or Hybrid Immunity Against Omicron-Associated Severe Outcomes Among Community-Dwelling Adults. Clin Infect Dis. 2024 May 15;78(5):1372-1382. doi: 10.1093/cid/ciad716. PMID: 38001037; PMCID: PMC11093681.