Figure 3.

Hazard ratios (with 95% confidence intervals) for bivalent boosters against severe COVID-19 outcomes stratified by age group among people aged ≥ 65 years living in Finland during September 2022–February 2023 and March–August 2023 (n = 1,191,871)

The hazard ratios for < 14 days since bivalent booster (no immune response and selection bias) and > 300 days since bivalent booster (exceeding the interquartile range of the maximum time since bivalent booster) are presented in Supplementary Tables S7–S8.