During periods of delta and omicron variant dominance, U.S. veterans who had received SARS-CoV-2 vaccinations had significantly lower odds of 30-day morbidity and mortality compared with no vaccination, a retrospective cohort study shows. “The vaccination type and number of doses had a significant association with outcomes,” the authors conclude.
Adults with documented SARS-CoV-2 infections (mean age, 59.4 ± 16.3 years; 87% male) in July through Nov. 2021 (delta) and Jan. through June 2022 (omicron) had these outcomes based on stays in hospital, intensive care unit admissions, use of ventilation, and mortality measured 30 days after a positive test result for SARS-CoV-2: “In the delta period, 95,336 patients had infections with 47.6% having at least one vaccine dose, compared with 184,653 patients in the omicron period, with 72.6% vaccinated. After adjustment for patient demographic and clinical characteristics, in the delta period, two doses of the mRNA vaccines were associated with lower odds of hospital admission (adjusted odds ratio 0.41 (95% confidence interval 0.39 to 0.43)), intensive care unit admission (0.33 (0.31 to 0.36)), ventilation (0.27 (0.24 to 0.30)), and death (0.21 (0.19 to 0.23)), compared with no vaccination. In the omicron period, receipt of two mRNA doses were associated with lower odds of hospital admission (0.60 (0.57 to 0.63)), intensive care unit admission (0.57 (0.53 to 0.62)), ventilation (0.59 (0.51 to 0.67)), and death (0.43 (0.39 to 0.48)). Additionally, a third mRNA dose was associated with lower odds of all outcomes compared with two doses: hospital admission (0.65 (0.63 to 0.69)), intensive care unit admission (0.65 (0.59 to 0.70)), ventilation (0.70 (0.61 to 0.80)), and death (0.51 (0.46 to 0.57)). The Ad26.COV2.S vaccination [Janssen/Johnson & Johnson] was associated with better outcomes relative to no vaccination, but higher odds of hospital stay and intensive care unit admission than with two mRNA doses. BNT162b2 [Pfizer/BioNTech] was generally associated with worse outcomes than mRNA-1273 [Moderna] (adjusted odds ratios between 0.97 and 1.42).”