Post by Nadica (She/Her) on Dec 3, 2024 1:45:27 GMT
Risks of SARS-CoV-2 JN.1 Infection and COVID-19–Associated Emergency Department Visits/Hospitalizations Following Updated Boosters and Prior Infection: A Population-Based Cohort Study - Published June 26, 2024
Abstract
Background
Data on protection afforded by updated coronavirus disease 2019 (COVID-19) vaccines (bivalent/XBB 1.5 monovalent) against the emergent JN.1 variant remain limited.
Methods
We conducted a retrospective population-based cohort study among all boosted Singaporeans aged ≥18 years during a COVID-19 wave predominantly driven by JN.1, from 26 November 2023 to 13 January 2024. Multivariable Cox regression was used to assess risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and COVID-19–associated emergency department (ED) visits/hospitalizations, stratified by vaccination status/prior infection; with individuals last boosted ≥1 year used as the reference category. Vaccination and infection status were classified using national registries.
Results
A total of 3 086 562 boosted adult Singaporeans were included in the study population, accounting for 146 863 476 person-days of observation. During the JN.1 outbreak, 28 160 SARS-CoV-2 infections were recorded, with 2926 hospitalizations and 3747 ED visits. Compared with individuals last boosted ≥1 year earlier with ancestral monovalent vaccines, receipt of an updated XBB.1.5 booster 8–120 days earlier was associated with lower risk of JN.1 infection (adjusted hazard ratio [aHR], 0.59 [95% confidence interval (CI), .52–.66]), COVID-19–associated ED visits (0.50 [.34–.73]), and hospitalizations (0.58 [.37–.91]), while receipt of a bivalent booster 121–365 days earlier was associated with lower risk of JN.1 infection (0.92 [.88–.95]) and ED visits (0.80 [.70–.90]). Lower risk of COVID-19 hospitalization during the JN.1 outbreak (aHR, 0.57 [95% CI, .33–.97]) was still observed following receipt of an updated XBB.1.5 booster 8–120 days earlier, even when analysis was restricted to previously infected individuals.
Conclusions
Recent receipt of updated boosters conferred protection against SARS-CoV-2 infection and ED visits/hospitalizations during a JN.1 variant wave, in both previously infected and uninfected individuals. Annual booster doses confer protection during COVID-19 endemicity.
Abstract
Background
Data on protection afforded by updated coronavirus disease 2019 (COVID-19) vaccines (bivalent/XBB 1.5 monovalent) against the emergent JN.1 variant remain limited.
Methods
We conducted a retrospective population-based cohort study among all boosted Singaporeans aged ≥18 years during a COVID-19 wave predominantly driven by JN.1, from 26 November 2023 to 13 January 2024. Multivariable Cox regression was used to assess risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and COVID-19–associated emergency department (ED) visits/hospitalizations, stratified by vaccination status/prior infection; with individuals last boosted ≥1 year used as the reference category. Vaccination and infection status were classified using national registries.
Results
A total of 3 086 562 boosted adult Singaporeans were included in the study population, accounting for 146 863 476 person-days of observation. During the JN.1 outbreak, 28 160 SARS-CoV-2 infections were recorded, with 2926 hospitalizations and 3747 ED visits. Compared with individuals last boosted ≥1 year earlier with ancestral monovalent vaccines, receipt of an updated XBB.1.5 booster 8–120 days earlier was associated with lower risk of JN.1 infection (adjusted hazard ratio [aHR], 0.59 [95% confidence interval (CI), .52–.66]), COVID-19–associated ED visits (0.50 [.34–.73]), and hospitalizations (0.58 [.37–.91]), while receipt of a bivalent booster 121–365 days earlier was associated with lower risk of JN.1 infection (0.92 [.88–.95]) and ED visits (0.80 [.70–.90]). Lower risk of COVID-19 hospitalization during the JN.1 outbreak (aHR, 0.57 [95% CI, .33–.97]) was still observed following receipt of an updated XBB.1.5 booster 8–120 days earlier, even when analysis was restricted to previously infected individuals.
Conclusions
Recent receipt of updated boosters conferred protection against SARS-CoV-2 infection and ED visits/hospitalizations during a JN.1 variant wave, in both previously infected and uninfected individuals. Annual booster doses confer protection during COVID-19 endemicity.