ArticleBMJ (Clinical research ed.)2023
Comparative effectiveness of bivalent BA.4-5 and BA.1 mRNA booster vaccines among adults aged ≥50 years in Nordic countries: nationwide cohort study.
Article in BMJ (Clinical research ed.), 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 53 papers, 4 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
53 citing papers in PubMed, 4 syntheses or guidelines pooled it, 78 citations in OpenAlex.
- Vaccine effectiveness across the Omicron evolutionary spectrum (BA.2, BA.5, XBB, JN.1, KP.3): a systematic review of studies published 2022-2025.BMC infectious diseases · 2026Pooled it
- Methodological challenges using routine clinical care data for real-world evidence: a rapid review utilizing a systematic literature search and focus group discussion.BMC medical research methodology · 2025Pooled it
- Monitoring COVID-19 vaccine effectiveness against COVID-19 hospitalisation and death using electronic health registries in ≥65 years old population in six European countries, October 2021 to November 2022.Influenza and other respiratory viruses · 2023Pooled it
- Relative effectiveness of bivalent COVID-19 vaccine: a systematic review and meta-analysis.Frontiers in medicine · 2023Pooled it
- Safety and Immunogenicity of a Fourth Dose of Omicron BA.1-Adapted BNT162b2 COVID-19 Vaccines in Adults 18-55 Years Old.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2026Trial
- Original COVID-19 priming regimen impacts the immunogenicity of bivalent BA.1 and BA.5 boosters.Nature communications · 2024Trial
- A Bivalent Omicron-BA.4/BA.5-Adapted BNT162b2 Booster in ≥12-Year-Olds.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2024Trial
- Retrospective cohort study of mRNA COVID-19 vaccine-associated enhanced disease in the Vaccine Safety Datalink, 2021-23.Human vaccines & immunotherapeutics · 2026Article
- Immunogenicity, Tolerability, and Safety of BA.1-Adapted BNT162b2 Vaccine in 18- to 55-Year-Olds Previously Vaccinated with BNT162b2 or Who Were COVID-19 Vaccine-Naive.Infectious diseases and therapy · 2026Article
- Feasibility of conducting brand-specific influenza vaccine effectiveness studies in three Nordic countries, Denmark, Finland, Sweden.Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin · 2026Article
- Article
- The presence of neutralizing antibodies against omicron subvariants among a vaccinated cohort at one year after the first dose of vaccination in Malaysia.Scientific reports · 2025Article
- Long term bivalent mRNA vaccine effectiveness against COVID-19 hospitalisations and deaths in Portugal: a cohort study based on electronic health records.BMC infectious diseases · 2025Article
- Viral sepsis-induced mortality of older patients infected by the Omicron subvariant BA.5 of SARS-CoV-2: a retrospective study.BMC infectious diseases · 2025Article
- Comparison of two methods for the estimation of COVID-19 vaccine effectiveness of the autumnal booster within the VEBIS-EHR network in 2022/23.Epidemiology and infection · 2025Article
- Humoral and cellular responses to a fifth bivalent SARS-CoV-2 vaccine dose in patients with immune-mediated inflammatory diseases on tumour necrosis factor inhibitors: a prospective cohort study.The Lancet regional health. Europe · 2025Article
- Overview of approved COVID-19 vaccines in the EU, recommendations for use in Sweden and vaccine uptake over time: Report from the Swedish Medical Products Agency and the Public Health Agency of Sweden.Upsala journal of medical sciences · 2025Review
- Immunogenicity of bivalent versus monovalent mRNA booster vaccination among adult paramedics in Canada who had received three prior mRNA wild-type doses.Access microbiology · 2025Article
- COVID-19 Vaccination Recommendations for 2024-2025 in Korea.Infection & chemotherapy · 2024Review
- Pulmonary embolism after SARS-CoV-2 vaccination.Vaccine: X · 2024Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
10 authors at 5 institutions in 4 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectiveTo estimate the effectiveness of the bivalent mRNA booster vaccines containing the original SARS-CoV-2 and omicron BA.4-5 or BA.1 subvariants as the fourth dose against severe covid-19.
designNationwide cohort analyses, using target trial emulation.
settingDenmark, Finland, Norway, and Sweden, from 1 July 2022 to 10 April 2023.
participantsPeople aged ≥50 years who had received at least three doses of covid-19 vaccine (that is, a primary course and a first booster).
main outcome measuresThe Kaplan-Meier estimator was used to compare the risk of hospital admission and death related to covid-19 in people who received a bivalent Comirnaty (Pfizer-BioNTech) or Spikevax (Moderna) BA.4-5 or BA.1 mRNA booster vaccine as a fourth dose (second booster) with three dose (first booster) vaccinated people and between four dose vaccinated people.
resultsA total of 1 634 199 people receiving bivalent BA.4-5 fourth dose booster and 1 042 124 receiving bivalent BA.1 fourth dose booster across the four Nordic countries were included. Receipt of a bivalent BA.4-5 booster as a fourth dose was associated with a comparative vaccine effectiveness against admission to hospital with covid-19 of 67.8% (95% confidence interval 63.1% to 72.5%) and a risk difference of -91.9 (95% confidence interval -152.4 to -31.4) per 100 000 people at three months of follow-up compared with having received three doses of vaccine (289
conclusionVaccination with bivalent BA.4-5 or BA.1 mRNA booster vaccines as a fourth dose was associated with reduced rates of covid-19 related hospital admission and death among adults aged ≥50 years. The protection afforded by the bivalent BA.4-5 and BA.1 boosters did not differ significantly when directly compared, and any potential difference would most likely be very small in absolute numbers.
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