Abstract
Background
Vaccination has been shown to be highly effective in preventing death and severe disease from severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection. Currently few studies have directly compared vaccinated and unvaccinated patients with severe COVID‐19 in the intensive care unit (ICU).
Aims
Our aim was to compare the clinical characteristics and outcomes of vaccine recipients and unvaccinated patients with SARS‐CoV‐2 infection admitted to the ICU in a nationwide setting.
Materials and Methods
Data were extracted from the Short PeRiod IncideNce sTudy of Severe Acute Respiratory Infection Australia, in 57 ICUs during Delta and Omicron predominant periods of the COVID‐19 pandemic. The primary outcome was in‐hospital mortality. Secondary outcomes included duration of mechanical ventilation, ICU length of stay, hospital length of stay, and ICU mortality.
Results
2,970 patients were admitted to ICU across participating sites from 26 June 2021 to 8 February 2022. 1,134 (38.2%) patients were vaccine recipients, and 1,836 (61.8%) patients were unvaccinated. Vaccine recipients were older, more comorbid, and less likely to require organ support. Unadjusted in‐hospital mortality was greater in the vaccinated cohort. After adjusting for age, gender and comorbid status, no statistically significant association between in‐hospital or ICU mortality, and vaccination status, was apparent.
Conclusion
We found COVID‐19 infection can cause severe disease and death in vaccine recipients, though comorbid status and older age were significant contributors to mortality. Organ support requirements and the number of deaths were highest in the unvaccinated cohort.
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Keywords: COVID‐19, SARS‐CoV‐2, SARS‐CoV‐2 vaccine, breakthrough infection, intensive care