Vaccine. 2025 Sep 2;63:127687. doi: 10.1016/j.vaccine.2025.127687. Online ahead of print.
ABSTRACT
BACKGROUND: We aimed to estimate SARS-CoV-2 vaccine effectiveness (VE) against medically attended SARS-CoV-2 infection in Hong Kong.
METHODS: We conducted a test-negative design study in individuals aged 5-64 years who presented with recent-onset (≤3 days) acute respiratory illness from April 2023 through to August 2024. Vaccination was defined as receipt of SARS-CoV-2 vaccine within 6 months of medical presentation, and for a sensitivity analysis, within 12 months of medical presentation. VE against laboratory-confirmed SARS-CoV-2 infection was estimated separately for 5-17-year-olds and 18-64-year-olds by conditional logistic regression adjusted for potential confounders.
RESULTS: Within the age groups, there was no statistically significant difference in vaccination (within 6 months of medical presentation) proportions between cases and controls across strata of the assessed individual sociodemographic and health-related characteristics. A moderate VE of 64 % (95 % confidence interval, CI: 9-83 %) and 54 % (95 % CI: -39 to 77 %) was estimated in 5-17-year-olds and 18-64-year-olds, respectively. However, a higher VE of 85 % (95 % CI: 32-97 %) and a moderate VE of 59 % (95 % CI: 2-83 %) were estimated in 5-17-year-olds for mRNA and inactivated vaccines, respectively, although non-statistically significantly different (p = 0.33) whereas a lower VE of 29 % (95 % CI: -81 to 73 %) and a higher VE of 70 % (95 % CI: -5 to 92 %) were estimated in 18-64-year-olds for mRNA and inactivated vaccines, respectively, which were not statistically significantly different from each other (p = 0.38). VE estimates were higher for those who had had a previous SARS-CoV-2 infection compared with those who had not. VE was also higher in 5-17-year-olds who had self-tested for SARS-CoV-2 infection before medical presentation and lower in those who had not, whereas the opposite was observed in 18-64-year-olds.
CONCLUSIONS: SARS-CoV-2 vaccines provided substantial protection against medically attended SARS-CoV-2 infection in both children and adults in Hong Kong.
PMID:40902334 | DOI:10.1016/j.vaccine.2025.127687
