High-Dose Influenza Vaccines Are More Effective Than Standard-Dose Influenza Vaccines in Preventing Hospitalizations in Older Adults

Are high-dose influenza vaccines more effective in reducing hospitalizations in older adults than a standard dose?

Older adults who receive high-dose influenza vaccines experience fewer hospitalizations for pneumonia, influenza, or cardiovascular events than adults who receive a standard dose. (Level of Evidence = 2b)

The researchers pooled individual participant data from two large population-based, industry-sponsored, open-label randomized trials that enrolled community-dwelling adults at least 65 years of age. Adults were randomized to receive a high-dose influenza vaccine (n = 233,311) or a standard-dose vaccine (n = 233,009). Outcomes were assessed starting 14 days after vaccination until the following May 31. Hospitalizations for pneumonia or influenza occurred less often in adults receiving the high-dose vaccine than the standard-dose vaccine (0.56% vs 0.62%; number needed to treat [NNT] = 1,840; 95% CI, 1,017–9,591). Additionally, adults who received the high-dose vaccine had fewer hospitalizations for cardiovascular events (2.0% vs 2.16%; NNT = 731; 95% CI, 457–1,825). All-cause hospitalizations also were less likely in those who received the high-dose vaccine (8.5% vs 8.7%; NNT = 515; 95% CI, 282–3,023). No significant difference was found in all-cause mortality. Serious adverse events were similar in each group (6.8%). Using data from only two industry-sponsored trials is bothersome. However, the data are consistent with results from other randomized trials.

Study Design: Meta-analysis (randomized controlled trials)

Funding Source: Industry

Allocation: Unconcealed

Setting: Population-based

Reference: Johansen ND, Modin D, Pardo-Seco J, et al. Effectiveness of high-dose influenza vaccine against hospitalisations in older adults (FLUNITY-HD): an individual-level pooled analysis. Lancet. 2025; 406(10518): 2425-2434.