ArticleBMJ open2022
Effectiveness of influenza vaccination in the elderly: a population-based case-crossover study.
Article in BMJ open, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 10 papers.
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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.
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Who cites it
10 citing papers in PubMed, 11 citations in OpenAlex.
- Reactogenicity, safety, and immunogenicity of a quadrivalent seasonal influenza vaccine in adults aged 65 years and older: Phase 4 study results from India during December 2023-February 2024.Human vaccines & immunotherapeutics · 2025Trial
- Determinants of influenza vaccination uptake in older adults: findings from a retrospective cross-sectional study.BMC public health · 2026Article
- The safety of co-administration of recombinant zoster vaccine (Shingrix) and influenza vaccines in the elderly in VAERS during 2018-2024.Human vaccines & immunotherapeutics · 2025Article
- Association between influenza vaccine effectiveness and chronic diseases among older adults with dementia.Scientific reports · 2025Article
- Battling Influenza in Elderly Patients: A Case of Severe Influenza A With Complications in a High-Risk Patient.Cureus · 2025Article
- Enhancing flu vaccine responses in older adults: preliminary insights from the ISOLDA study on immunosenescence and antioxidant and anti-inflammatory approaches.Immunity & ageing : I & A · 2025Article
- Determinants of influenza vaccination uptake among older adults in Catalonia using a longitudinal population study: the role of public health campaigns.BMJ public health · 2025Article
- Promoting Influenza Vaccination Uptake Among Chinese Older Adults Based on Information-Motivation-Behavioral Skills Model and Conditional Economic Incentive: Protocol for Randomized Controlled Trial.Healthcare (Basel, Switzerland) · 2024Article
- Readiness of and barriers for community pharmacy professionals in providing and implementing vaccination services.BMC health services research · 2024Article
- The burden of influenza and the role of influenza vaccination in adults aged 50-64 years: A summary of available evidence.Human vaccines & immunotherapeutics · 2023Review
Corrections and comments
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Authors and funding
7 authors at 5 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThere is limited information regarding the effectiveness of influenza vaccines for older adults. Particularly, controlling for healthy senior bias is challenging in observational studies. We aimed to assess the efficacy of influenza vaccination in the elderly while addressing potential healthy senior bias and whether it was related to virus-vaccine strains matching.
methodTo control between-individual confounder, we used a case-crossover study design using Taiwan's National Health Insurance Research Dataset to analyse the association between influenza vaccination in older adults and the risk of hospitalisation for community-acquired pneumonia (CAP). Individuals were a 'case' in vaccinated years and a 'control' in unvaccinated years. The study periods were 2006/2007 and 2007/2008 seasons because virus-vaccine strains were matching in 2006/2007 season and unmatching in 2007/2008 season. Older adults were categorised into two groups: admitted for CAP during the pre-vaccination period (Admitted, n=311) and not hospital admitted for CAP (Non-admitted, n=572 432). The outcome was hospitalisation for CAP during the influenza period. Conditional logistic regression assessed influenza vaccine efficacy in reducing CAP.
resultsInfluenza vaccination had no protective effects in Admitted group. However, because of the tiny numbers in Admitted group, we could draw very limited conclusions. Receiving an influenza vaccine significantly prevented CAP in Non-admitted group only during the vaccine-circulating strain-matched year (OR, 0.72; 95% CI, 0.64 to 0.83). In addition, there was no protective effect against CAP hospitalisation among individuals with a Charlson Comorbidity Index score over 2.
conclusionInfluenza vaccine efficacy was associated with vaccine-circulating strain-matched. When vaccine-circulating strains were all matching, receiving a shot reduced the probability of CAP hospitalisation by 28% in Non-admitted group. However, high comorbidity may reduce the vaccine efficacy. Therefore, it is necessary to educate older adults to receive annual influenza vaccination and in combination with non-pharmaceutical interventions to reduce the risk of CAP.
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