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Is it worth having the flu vaccine

Nov 10, 2026 · 11 sources used · OpenNeedle synthesis
The short version: for most healthy adults under 65, the flu shot is a modest bet, not a sure thing. For people with diabetes or over 75, the evidence is stronger.

The honest answer depends on who you are. In working-age adults, the shot cut lab-confirmed flu by roughly half in one season [6], but protection swings wildly by season and strain: 23% against H3N2 in the UK one year [9], 43% in Europe another [7], and negative against H3N2 in hospitalized Spanish elderly in 2017/18 [8]. That is a real but unreliable benefit.

For people with diabetes, the picture is better. A meta-analysis of six observational studies found lower all-cause mortality [1], and a test-negative study found 46% protection against flu hospitalization [5]. For people over 75, a UK cohort found vaccination blunted the rise in all-cause deaths during high-flu periods [2]. These are observational, not randomized, so healthy-user bias can inflate them; one South African study found exactly that and called its own data inconclusive [4].

GroupOutcomeEffect
Adults 19-64 (Korea)Lab-confirmed flu~46-50% lower odds [6]
Adults 65+ (Korea)Lab-confirmed fluNot significant [6]
DiabeticsFlu hospitalization46% lower [5]
DiabeticsAll-cause mortalityLower, but high heterogeneity [1]
Elderly 65+ (Valencia)Flu hospitalization9.9%, not significant [8]

On safety, the main documented signal is Guillain-Barré syndrome. A VAERS analysis found a reporting signal for seasonal flu vaccines [10], and self-controlled analyses of the 2009 H1N1 vaccine found a small excess of roughly 1.5 to 2.8 cases per million doses [11]. VAERS is voluntary reporting and detects little by design. The most informative comparison, vaccinated versus truly unvaccinated over years, is not in this retrieval.

My call: worth it if you are over 65, diabetic, or otherwise high-risk, where the mortality signal is consistent across studies [1][2][3]. For a healthy adult under 50, the benefit is real but modest and season-dependent, and skipping it is a defensible choice. Confidence: moderate for high-risk groups, low for healthy working-age adults.

Keep digging

Sources used 11

  1. 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 Vaccines (2020) meta-analysis Mixed

    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
  2. Effect of influenza vaccination on excess deaths occurring during periods of high circulation of influenza: cohort study in elderly people BMJ (2004) primary study Strong

    Among 24,535 people aged over 75 in UK primary care, influenza vaccination blunted the rise in all-cause mortality during high influenza circulation; the estimated effectiveness against influenza-associated death was 83%, though imprecise.

    DOI: 10.1136/bmj.38198.594109.ae
  3. Modelling the population effectiveness of the national seasonal influenza vaccination programme in Scotland: The impact of targeting all individuals aged 65 years and over Influenza and Other Respiratory Viruses (2019) primary study Strong

    Using Scottish routine data from 1981-2012, Poisson GAM models estimate that the mid-2000 policy extending influenza vaccination to all people aged 65+ was associated with significant reductions in excess all-cause mortality, cardiovascular and COPD mortality, and COPD hospitali…

    DOI: 10.1111/irv.12583
  4. Effectiveness of influenza vaccination in the elderly in South Africa Epidemiology and Infection (2008) primary study Strong

    In a nested case-control study of medically insured elderly in South Africa, influenza vaccination was associated with fewer serious complications after full adjustment, but sensitivity analysis suggested healthy-user bias could explain the findings, so the data were inconclusiv…

    DOI: 10.1017/s0950268808001386
  5. Effect of Influenza Vaccination in Preventing Laboratory-Confirmed Influenza Hospitalization in Patients With Diabetes Mellitus Clinical Infectious Diseases (2020) primary study Strong

    In diabetic patients, current-season influenza vaccination reduced laboratory-confirmed influenza hospitalization by 46%, and vaccination in prior seasons only by 44%.

    DOI: 10.1093/cid/ciaa564
  6. Case-Control Study of the Effectiveness of the 2010-2011 Seasonal Influenza Vaccine for Prevention of Laboratory-Confirmed Influenza Virus Infection in the Korean Adult Population Clinical and Vaccine Immunology (2013) primary study Strong

    A retrospective matched case-control study in 1,449 South Korean adults found the 2010-2011 seasonal influenza vaccine was 45.8-49.5% effective against laboratory-confirmed influenza, especially influenza A, with no significant effect in adults ≥65 years or against influenza B.

    DOI: 10.1128/cvi.00009-13
  7. Early estimates of seasonal influenza vaccine effectiveness in Europe among target groups for vaccination: results from the I-MOVE multicentre case–control study, 2011/12 Eurosurveillance (2012) primary study Strong

    In a 2011/12 European multicentre test-negative case-control study, the adjusted seasonal influenza vaccine effectiveness against laboratory-confirmed influenza A(H3) among vaccination target groups was 43.0% (95% CI -0.4 to 67.7), indicating a low-to-moderate but imprecise esti…

    DOI: 10.2807/ese.17.15.20146-en
  8. Influenza vaccine effectiveness against laboratory-confirmed influenza in hospitalised adults aged 60 years or older, Valencia Region, Spain, 2017/18 influenza season Eurosurveillance (2019) primary study Strong

    In hospitalised adults aged ≥60 years in Valencia during 2017/18, overall influenza vaccine effectiveness was low and non-significant, with significant protection only against A(H1N1)pdm09 and prior vaccination against B/Yamagata.

    DOI: 10.2807/1560-7917.es.2019.24.31.1800461
  9. Vaccine effectiveness of 2011/12 trivalent seasonal influenza vaccine in preventing laboratory-confirmed influenza in primary care in the United Kingdom: evidence of waning intra-seasonal protection Eurosurveillance (2013) primary study (observational test-negative case-control study) Strong

    The 2011/12 trivalent seasonal influenza vaccine provided low overall protection (23% adjusted VE) against influenza A(H3N2) infection in UK primary care with significant intraseasonal waning (VE decline from 53% to 12% by time since vaccination), but high protection (92%) again…

    DOI: 10.2807/ese.18.05.20389-en
  10. A study of the association between seasonal influenza vaccines and the increased risk of Guillain–Barré syndrome using Vaccine Adverse Event Reporting System, 2018–2019 Die Pharmazie (2021) primary study Strong

    In VAERS 2018-2019, seasonal influenza vaccines had an adjusted reporting odds ratio for Guillain-Barré syndrome of 3.44 (95% CI 2.40-4.95), with most cases within 14 days and no adjusted male-sex or younger-age risk effect.

    DOI: 10.31083/ph.2021.1578
  11. 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 Pharmacoepidemiology and Drug Safety (2012) primary study Strong

    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

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