296. SARS-CoV-2 Illness Severity and Early Hospitalization Outcomes in a Multicenter Prospective Cohort Study Among Veterans

Abstract Background Over 600,000 SARS-CoV-2 infections and 20,000 deaths have occurred among users of the Veterans Health Administration, the US’s largest integrated health care system. We explored early outcomes of SARS-COV-2 infection in Veterans. Methods An ongoing, prospective longitudinal cohort study of Veterans ages ≥ 18 enrolled 1,826 participants (29.0% inpatient; 49.1% vaccinated; 68.3% SARS-CoV-2-positive; 85.0% male, mean age = 57.1 years) seeking inpatient or outpatient care after SARS-CoV-2 testing at 15 Department of Veterans Affairs medical centers in July 2020 to February 13, 2022. Using multivariable regression, we estimated relationships of baseline demographic characteristics, COVID-19 vaccination, and clinical history to illness severity and cumulative length of hospital stay within 60 days of study entry. Illness severity was defined by a Veterans Affairs adaptation of the WHO COVID-19 severity scale and included 4 levels (mild, moderate, severe, or death). We derived the Charlson co-morbidity index (CCI) and other baseline characteristics from electronic health data and study questionnaires, and reported qualitative SARS-CoV-2 IgG responses using inpatients’ study-collected blood specimens. Results High CCI scores (≥ 5) occurred in 47 (42.7%) vaccinated SARS-CoV-2-positive inpatients and 47 (21.2%) unvaccinated. Severe illness occurred in 17 (15.5%) vaccinated inpatients, 37 (16.7%) unvaccinated inpatients, 4 (0.9%) vaccinated outpatients, and 3 (0.7%) unvaccinated outpatients. Eleven (10%) of 110 vaccinated SARS-CoV-2-positive inpatients died, as did 15 (6.8%) of the 222 unvaccinated. In SARS-CoV-2-positive inpatients, a one-step higher CCI was associated with more severe illness (aOR 1.10, 95% CI 1.01-1.20) and more hospitalization days (aIRR 1.06, 95% CI 1.03-1.10), adjusting for vaccination status. Respectively, 93% of vaccinated and 63% of unvaccinated SARS-CoV-2 positive inpatients with baseline antibody results had an anti-spike IgG response. Conclusion In an ongoing longitudinal cohort study of COVID-19 in US Veterans, comorbidity burden was higher among vaccinated than unvaccinated inpatients and was associated with more severe illness and hospitalization days, independent of vaccination status. Disclosures Christine M. Hunt, MD, MPH, Adaptive Phage Therapeutics: Advisor/Consultant|Akebia: Advisor/Consultant|Galmed: Advisor/Consultant|Otsuka: Advisor/Consultant|Palladio: Advisor/Consultant.