Table 3 Relative vaccine effectiveness (rVE) and NNV by risk groups

From: Incremental benefit of high dose compared to standard dose influenza vaccine in reducing hospitalizations

Influenza season

Risk group*

Adjusted rVE ** (95% CI) [%]

NNV‡ (95% CI)

2022–2023

All

27% (−12–61%)

2262 (1012–\(\infty\))

Low risk

4216 (1866–\(\infty\))

Medium-high risk

1289 (571–\(\infty\))

2023–2024

All

7% (−36% – 42%)

7662 (1293–\(\infty\))

Low risk

12,901 (2178–\(\infty\))

Medium-high risk

4719 (797–\(\infty\))

  1. *Risk groups were determined empirically. Medium to high: (1) individuals aged 75 y and above with at least two comorbidities, (2) individuals younger than 75 y with cardiovascular background, and (3) individuals who are home-bounded.
  2. **Based on 1:1 bootstrap matching with 1000 repetitions. The cumulative distribution of vaccination timing by vaccine type is presented in Supplementary Fig. 1.
  3. ‡The NNV was based on the computed adjusted rVE. NNV estimates should be interpreted with caution due to wide confidence intervals and an infinite upper bound (resulting from a non-significant rVE).
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