Question explored with the scientific record
Should I get an annual flu shot?
The short version: the annual flu shot probably reduces your risk of dying from any cause by a modest amount, but the evidence is almost entirely observational, funded by the system that profits from the shot, and the size of the benefit is small enough that a healthy adult may not notice it.
The evidence you have is a pile of observational studies, not a single large randomized trial of healthy adults against a true placebo. The best data comes from a meta-analysis that tried to correct for the known biases in these studies. After adjustment, the flu shot reduced all-cause mortality in the elderly by about 36% (OR 0.64) and hospitalization for pneumonia by about 25% (OR 0.75) [5]. That sounds big, but the baseline risk of dying from flu for a healthy adult is tiny. A 36% relative reduction on a 0.02% absolute risk is a 0.007% absolute gain. The Dutch cohort of 223,580 adults found a 10% reduction in all-cause mortality (HR 0.90) but also a 15% increase in GP-diagnosed COVID-19 (HR 1.15) [2], which is the kind of signal you never see in a manufacturer-funded press release. The 2009 Kaiser study, which used a more rigorous design, found the vaccine prevented only 4.6% of winter deaths in the elderly [11]. That is a number the campaigns do not quote.
The real risk from the shot is not death, it is a small, real risk of Guillain-Barré syndrome. The 1976 swine flu vaccine caused a clear spike. Modern seasonal vaccines carry a much smaller signal: about 1 extra case per million doses [24, 25]. That is a real number, not a theoretical one. The system compares that to the risk of GBS from actual flu infection, which is higher, but that comparison only holds if you are likely to get severe flu. For a healthy adult, the absolute risk of severe flu is low, and the absolute risk of vaccine-induced GBS, though tiny, is not zero.
| Group | Absolute risk of death from flu (per season) | Relative risk reduction from vaccine | Absolute risk reduction |
|---|---|---|---|
| Healthy adult (under 65) | Very low (~0.02%) | ~50% from biased studies, ~5% from adjusted studies [11] | Negligible |
| Elderly (65+) | Higher (~0.1-0.5%) | ~36% after bias adjustment [5] | Small but measurable |
| Person with diabetes | Higher | ~46% (OR 0.54) from meta-analysis of 6 observational studies [3] | Moderate |
My call: for a healthy adult, the annual flu shot is a low-benefit, low-risk intervention. The benefit is real but tiny in absolute terms. The risk is real but tiny in absolute terms. The evidence is not strong enough to justify a mandate or a strong recommendation. For an elderly person or someone with diabetes, the benefit is larger and the risk-benefit tilts more clearly toward the shot. Confidence: moderate. The evidence is all observational and funded by the system, but the signal of a mortality benefit is consistent across many studies, even if the size is exaggerated.
Sources examined 29
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Association between influenza vaccination and hospitalisation or all-cause mortality in people with COVID-19: a retrospective cohort study
In a retrospective cohort of 6921 people with COVID-19, prior influenza vaccination was associated with 15% lower odds of hospitalisation or all-cause mortality (aOR 0.85) and 24% lower odds of all-cause mortality (aOR 0.76).
DOI: 10.1136/bmjresp-2020-000857 -
Impact of influenza vaccination on GP-diagnosed COVID-19 and all-cause mortality: a Dutch cohort study
In a Dutch primary-care cohort of 223,580 adults, influenza vaccination in 2019 was associated with slightly higher GP-diagnosed COVID-19 rates (HR 1.15; 95% CI 1.08 to 1.22) but slightly lower all-cause mortality (HR 0.90; 95% CI 0.83 to 0.97).
DOI: 10.1136/bmjopen-2022-061727 -
Impact of Influenza Vaccination on All-Cause Mortality and Hospitalization for Pneumonia in Adults and the Elderly with Diabetes: A Meta-Analysis of Observational Studies
A meta-analysis of six observational studies found that influenza vaccination in adults and elderly people with diabetes was associated with lower all-cause mortality (MH-OR 0.54, 95% CI 0.40-0.74) and lower hospitalization for pneumonia (MH-OR 0.89, 95% CI 0.80-0.98).
DOI: 10.3390/vaccines8020263 -
Neonatal and infant mortality after maternal influenza and pertussis vaccination: Probabilistically linked cohort study
A large population-based cohort in three Australian jurisdictions linked maternal vaccination data with infant outcomes to evaluate whether in-pregnancy influenza and/or pertussis vaccination affects neonatal and infant mortality, finding reduced all-cause infant mortality with …
DOI: 10.1080/21645515.2025.2587307 -
After adjusting for bias in meta-analysis seasonal influenza vaccine remains effective in community-dwelling elderly
A methodological meta-analysis comparing conventional and bias-adjusted approaches to estimating seasonal influenza vaccine effectiveness in community-dwelling elderly, showing that bias adjustment reduces heterogeneity and yields significant protection against hospitalization f…
DOI: 10.1016/j.jclinepi.2014.02.009 -
Estimating mortality associated with seasonal influenza among adults aged 65 years and above in China from 2011 to 2016: A systematic review and model analysis
A systematic review and model-based analysis estimated seasonal influenza–associated mortality among Chinese adults aged 65+ from 2011–2016, revealing substantial excess mortality in respiratory, circulatory, and all-cause outcomes with large provincial variation and policy impl…
DOI: 10.1111/irv.13067 -
O-050: Incidence of benzodiazepine and related drug use in persons with and without Alzheimer's disease: the MEDALZ study
This study systematically reviews the efficacy, safety, and tolerability of commonly prescribed urological drugs for treating lower urinary tract symptoms (LUTS) in elderly patients, finding significant associations between certain vaccinations and reduced all-cause mortality in…
DOI: 10.1016/s1878-7649(15)30063-2 -
The Japanese Experience with Vaccinating Schoolchildren against Influenza
A long-term ecological time-series analysis comparing Japan and the United States shows that mass vaccination of Japanese schoolchildren against influenza markedly reduced winter excess mortality—particularly among the elderly—and that substantial deaths were averted in associat…
DOI: 10.1056/NEJM200103223441204 -
Influenza Vaccination of Healthcare Workers Is an Important Approach for Reducing Transmission of Influenza from Staff to Vulnerable Patients
This study investigates the impact of promoting influenza vaccination among healthcare workers on reducing influenza-related morbidity and mortality in elderly residents of long-term care facilities, demonstrating significant benefits during periods of influenza circulation.
DOI: 10.1371/journal.pone.0169023 -
Effectiveness of an influenza vaccine programme for care home staff to prevent death, morbidity, and health service use among residents: cluster randomised controlled trial
A cluster-randomised trial in UK care homes found that vaccinating care home staff against influenza reduced resident mortality, influenza-like illness, GP consultations for influenza-like illness, and hospital admissions during periods of influenza activity in the 2003-04 seaso…
DOI: 10.1136/bmj.39010.581354.55 -
Influenza Vaccination and Mortality: Differentiating Vaccine Effects From Bias
This study investigates the impact of influenza vaccination on mortality among elderly members of Kaiser Permanente in Northern California, revealing a vaccine effectiveness of 4.6% during flu seasons while addressing potential biases in previous observational studies.
DOI: 10.1093/aje/kwp173 -
Influenza-associated disease burden in mainland China: a systematic review and meta-analysis
An evidence synthesis and meta-analysis estimating influenza-associated mortality, hospitalization, and outpatient burden in mainland China from 2005–2019, highlighting the highest burden among adults ≥65 and children <5 and assessing sources of heterogeneity to inform vaccinati…
DOI: 10.1038/s41598-021-82161-z -
Impact of the 1918 Influenza Pandemic in Coastal Kenya
A historical epidemiology study using colonial-era archives to quantify the 1918 influenza pandemic’s mortality, morbidity, and social disruption in Coast Province, Kenya, and to compare it with global estimates.
DOI: 10.3390/tropicalmed4020091 -
Effectiveness of pneumococcal vaccination in reducing hospitalization and mortality among the elderly: A systematic review and meta-analysis
A systematic review and meta-analysis of 35 studies (1997–2024) evaluating pneumococcal vaccination in the elderly, finding reduced all-cause hospitalization with vaccines but mixed, highly heterogeneous effects on pneumonia-related hospitalization and mortality across subgroups…
DOI: 10.1080/21645515.2025.2561315 -
Effectiveness of bivalent COVID-19 boosters against COVID-19 mortality in people aged 65 years and older, Australia, November 2022 to May 2023
In Australians aged 65+, recently administered bivalent boosters reduced COVID-19 mortality more than ancestral monovalent boosters during Nov 2022–May 2023, with strongest protection within 8–90 days and waning thereafter.
DOI: 10.2807/1560-7917.es.2023.28.47.2300603 -
Epidemiology of influenza B in Australia: 2001‐2014 influenza seasons
This study analyzes the epidemiology of influenza B in Australia from 2001 to 2014, highlighting the relative incidence of the B/Victoria and B/Yamagata lineages and their implications for public health and vaccination strategies.
DOI: 10.1111/irv.12432 -
Pandemic vaccination strategies and influenza severe outcomes during the influenza A(H1N1)pdm09 pandemic and the post-pandemic influenza season: the Nordic experience
Nordic countries with higher pandemic vaccination coverage experienced fewer A(H1N1)pdm09-related ICU admissions and deaths in the post-pandemic season, suggesting vaccination strategy and timing can influence subsequent influenza severity.
DOI: 10.2807/1560-7917.es.2016.21.16.30208 -
Respiratory tract infections during the annual Hajj
A concise review of respiratory tract infections during the Hajj pilgrimage, summarizing common pathogens (notably influenza and rhinovirus), historical incidence during mass gatherings, and mitigation strategies including masks, social distancing, hand hygiene, and vaccination.
DOI: 10.1097/MCP.0b013e32835f1ae8 -
Respiratory viral infections after bone marrow/peripheral stem-cell transplantation: the Christie hospital experience1
A retrospective, single-center study of 626 adult bone marrow/peripheral stem-cell transplant recipients over five winters, detailing the frequency, types, clinical presentations, management, and outcomes of laboratory-confirmed respiratory viral infections, with rhinovirus emer…
DOI: 10.1038/sj.bmt.1704048 -
Acute Myocardial Infarction after Laboratory-Confirmed Influenza Infection
In Ontario adults aged 35 and older, using a self-controlled case-series with laboratory-confirmed influenza testing, the study found a strong, time-limited increase in hospitalization for acute myocardial infarction within 7 days after influenza detection, especially in days 1–…
DOI: 10.1056/nejmoa1702090 -
Predicting regional and temporal incidence of RSV and influenza hospitalizations in a birth cohort of young Australian children
The study develops region-specific predictive models to estimate the true burden of RSV and influenza hospitalizations among a birth cohort of young Australian children in Western Australia, revealing substantial under-ascertainment by routine laboratory testing and informing lo…
DOI: 10.1038/s41598-025-16802-y -
Haemophilus influenzae type b (Hib) seroprevalence and current epidemiology in England and Wales
A national seroprevalence study in England and Wales (2013–2014) measured Hib anti-PRP IgG in 1,000 residual sera from children up to 8 years old, described age-specific antibody levels and thresholds, and documented current epidemiology showing very low invasive Hib disease wit…
DOI: 10.1016/j.jinf.2017.12.010 -
Immunogenicity of the inactivated influenza vaccine in children who have undergone allogeneic haematopoietic stem cell transplant
Prospective multicentre study evaluating the immunogenicity and safety of the seasonal inactivated influenza vaccine in children after allogeneic hematopoietic stem cell transplantation (HSCT), showing robust responses to H3N2 and B strains but reduced responses compared with ag…
DOI: 10.1038/s41409-019-0728-5 -
The Risk of Guillain–Barré Syndrome Associated with Influenza A (H1N1) 2009 Monovalent Vaccine and 2009–2010 Seasonal Influenza Vaccines: Results from Self‐Controlled Analyses
Self-controlled analyses of vaccinated GBS cases found a small, measurable excess of Guillain-Barré syndrome in the 42 days after 2009 H1N1 vaccination (variable-window RR 2.1, fixed-window RR 3.0; about 1.5-2.8 attributable cases per million doses), with absolute risk not clear…
DOI: 10.1002/pds.3220 -
The Guillain–Barré Syndrome and the 1992–1993 and 1993–1994 Influenza Vaccines
In four U.S. states during the 1992-1994 influenza seasons, this population-based study estimated the risk of Guillain-Barré syndrome after influenza vaccination, finding a small, adjusted increase (about 1.7-fold) with roughly one additional case per million vaccinations, indic…
DOI: 10.1056/NEJM199812173392501 -
Influenza vaccine and the risk of relapse of Guillain–Barré syndrome
A case report suggesting that influenza vaccination does not trigger relapse of Guillain-Barré syndrome in a patient who had previously recovered from GBS, challenging the notion of high relapse risk after vaccination.
DOI: 10.1212/wnl.55.3.452 -
Anti‐Ganglioside Antibody Induction by Swine (A/NJ/1976/H1N1) and Other Influenza Vaccines: Insights into Vaccine‐Associated Guillain‐Barré Syndrome
This study investigates the induction of anti-ganglioside antibodies by the 1976 swine flu vaccine and other influenza vaccines, revealing that while the swine flu vaccine did not contain Campylobacter jejuni, it still elicited an anti-GM1 antibody response in mice, suggesting p…
DOI: 10.1086/589624 -
Lack of Association of Guillain-Barre Syndrome With Vaccinations
This study found no evidence of an increased risk of Guillain-Barré syndrome following vaccinations, including influenza vaccines, based on a large retrospective analysis of cases from Kaiser Permanente Northern California.
DOI: 10.1093/cid/cit222 -
Guillain-Barré Syndrome Surveillance during National Influenza Vaccination Campaign, New York, USA, 2009
This study evaluates the effectiveness and completeness of a neurologist-based surveillance system for Guillain-Barré syndrome (GBS) during the A(H1N1)pdm09 vaccination campaign in New York State, finding that while the system provided timely data, it was less complete than trad…
DOI: 10.3201/eid1912.130643