Effectiveness and durability of mRNA-1273 BA.4/BA.5 bivalent vaccine (mRNA-1273.222) against SARS-CoV-2 BA.4/BA.5 and XBB sublineages

Objectives To estimate the effectiveness and waning immunity of the bivalent BA.4-5 or BA.1 mRNA booster vaccine against Covid-19-related hospital admission and death in immunocompromised individuals. Design Nationwide cohort analyses using a matched cohort design. Setting Denmark, Finland, and Sweden, from 1 September 2022 to 31 October 2023. Participants All individuals aged 18 years or above with medical history of at least one immunocompromised condition, residency in Denmark, Finland or Sweden, no history of Covid-19-related hospitalization, and receipt of at least three Covid-19 vaccine doses as of study start, 1 September 2022. Individuals boosted with a BA.4-5 or BA.1 vaccine were matched 1:1 with unboosted individuals. Main outcome measures Country-combined vaccine effectiveness (VE) estimates against Covid-19 hospitalization and Covid-19-related death at day 270 of follow-up. Potential waning was assessed in 45-day intervals. Results A total of 352,762 BA.4-5 and 191,070 BA.1 booster vaccine doses were administered to immunocompromised individuals. At day 270, the comparative VE against Covid-19 hospitalization was 34.2% (95% CI, 7.1% to 61.3%) for the bivalent BA.4-5 vaccine (696 vs 1,128 events, risk difference [RD] per 100,000, -223.7, 95% CI, -411.5 to -36.0) and 42.6% (95% CI, 31.3% to 53.9%) for the BA.1 vaccine (395 vs 740 events, RD per 100,000, -385.0, -673.4 to -96.6) compared with matched unboosted. The comparative VE against Covid-19 death was 53.9% (95% CI, 38.6% to 69.3%) for the bivalent BA.4-5 vaccine (203 vs 457 events, RD per 100,000, -138.7, 95% CI, -195.5 to -81.9) and 57.9% (95% CI, 48.5% to 67.4%) for the BA.1 vaccine (112 vs 302 events, RD per 100,000, -220.6, -275.9 to -165.4). The VE estimates were highest in the first 45 days since eight days after vaccination (52.8% and 72.8% for bivalent BA.4-5 vaccine against Covid-19-related hospitalization and death, and 62.2% and 84.2% for bivalent BA.1 vaccine) and waned gradually during the 270 days of follow-up. Conclusions In immunocompromised individuals, vaccination with a bivalent BA.4-5 or BA.1 booster lowered the risk of Covid-19-related hospitalization and death over a follow-up period of 9 months. The effectiveness was highest during the first months since vaccination with subsequent gradual waning.

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Methodology of comparative studies on the relative effectiveness of COVID-19 vaccines: a systematic review

Bolormaa,

Shim,

Choi

et al. 2024

PHRP

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Objectives: This study aimed to comprehensively outline the methodological approaches used in published research comparing the vaccine effectiveness (VE) of coronavirus disease 2019 (COVID-19) vaccines.Methods: A systematic search was conducted on June 13, 2024, to identify comparative studies evaluating the effectiveness of mRNA versus non-mRNA and monovalent versus bivalent COVID-19 vaccines. We screened titles, abstracts, and full texts, collecting data on publication year, country, sample size, study population composition, study design, VE estimates, outcomes, and covariates. Studies that reported relative VE (rVE) were analyzed separately from those that did not.Results: We identified 25 articles comparing rVE between mRNA and non-mRNA COVID-19 vaccines, as well as between monovalent and bivalent formulations. Among the studies assessing VE by vaccine type, 126 did not provide rVE estimates. Comparative VE studies frequently employed retrospective cohort designs. Among the definitions of rVE used, the most common were hazard ratio and absolute VE, calculated as (1−odds ratio)×100. Studies were most frequently conducted in the United Kingdom and the United States, and the most common outcome was infection. Most targeted the general population and assessed the VE of mRNA vaccines using the AstraZeneca vaccine as a reference. A small proportion, 7.3% (n=11), did not adjust for any variables. Only 3 studies (2.0%) adjusted for all core confounding variables recommended by the World Health Organization.Conclusion: Few comparative studies of COVID-19 vaccines have incorporated rVE methodologies. Reporting rVE and employing a consistent set of covariates can broaden our understanding of COVID-19 vaccines.

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Effectiveness and durability of mRNA-1273 BA.4/BA.5 bivalent vaccine (mRNA-1273.222) against SARS-CoV-2 BA.4/BA.5 and XBB sublineages

Cited by 3 publications

References 25 publications

Comparative effectiveness of bivalent BA.4–5 or BA.1 mRNA booster vaccines among immunocompromised individuals across three Nordic countries: A nationwide cohort study

Comparative effectiveness of bivalent BA.4–5 or BA.1 mRNA booster vaccines among immunocompromised individuals across three Nordic countries: A nationwide cohort study

Comparative effectiveness of bivalent BA.4.5 or BA.1 mRNA booster vaccines among immunocompromised individuals across three Nordic countries: a nationwide cohort study

Methodology of comparative studies on the relative effectiveness of COVID-19 vaccines: a systematic review

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