Protection of Two and Three mRNA Vaccine Doses Against Severe Outcomes Among Adults Hospitalized With COVID-19-VISION Network, August 2021 to March 2022.

Background: We assessed coronavirus disease 2019 (COVID-19) vaccination impact on illness severity among adults hospitalized with COVID-19, August 2021-March 2022.
Methods: We evaluated differences in intensive care unit (ICU) admission, in-hospital death, and length of stay among vaccinated (2 or 3 mRNA vaccine doses) versus unvaccinated patients aged ≥18 years hospitalized for ≥24 hours with COVID-19-like illness and positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) molecular testing. We calculated odds ratios (ORs) for ICU admission and death and subdistribution hazard ratios (SHR) for time to hospital discharge adjusted for age, geographic region, calendar time, and local virus circulation.
Results: We included 27 149 SARS-CoV-2-positive hospitalizations. During both Delta- and Omicron-predominant periods, protection against ICU admission was strongest among 3-dose vaccinees compared with unvaccinated patients (Delta OR, 0.52 [95% CI, .28-.96]; Omicron OR, 0.69 [95% CI, .54-.87]). During both periods, risk of in-hospital death was lower among vaccinated compared with unvaccinated patients but ORs overlapped across vaccination strata. We observed SHR >1 across all vaccination strata in both periods indicating faster discharge for vaccinated patients.
Conclusions: COVID-19 vaccination was associated with lower rates of ICU admission and in-hospital death in both Delta and Omicron periods compared with being unvaccinated.
Competing Interests: Potential conflicts of interest. N. P. K. reported receiving grants from Pfizer, Merck, GlaxoSmithKline, Sanofi Pasteur, and Protein Science (now Sanofi Pasteur) outside the submitted work. B. E. D. reported consulting fees for advisory panel on HPV vaccination from Merck & Co and book royalties from Elsevier as well as Springer Nature. A. L. N. received institutional support from Pfizer for an unrelated study of meningococcal B vaccine safety during pregnancy and from Vir Biotechnology for an unrelated influenza study. S. R. received grant funding from GlaxoSmithKline. C. M. received institutional support from AstraZeneca for a COVID vaccine trial. G. V.-B. reported Sanofi for Tdap Vaccine Safety. M. G. reported receiving institutional support from CDC for the ambulatory US Flu/COVID VE network and HAIVEN adult inpatient flu/COVID VE network; from CDC-Vanderbilt for the IVY-3 PHS project and from CDC-Abt for the RECOVER study. All other authors declare no financial relationships with any organizations that might have an interest in the submitted work in the previous three years, and no other relationships or activities that could appear to have influenced the submitted work. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
(Published by Oxford University Press on behalf of Infectious Diseases Society of America 2022.)