Background: Researchers across the globe have continued their effort in identifying important risk factors for severe COVID-19 infection. Patient demographics including age, race, gender, and certain chronic medical conditions including cardiovascular disease, diabetes, hypertension, and heart failure have been identified as the important risk factors for severity. To simply the risk stratification process, the CHA2DS2-VASc score was found to be a strong clinical predictor of the disease severity in early COVID-19 populations. Additionally, chronic kidney disease (CKD), male gender and obesity were identified as other important independent risk factors for severe COVID-19. Many of these observations were made within the first year of the pandemic and have not been significantly reassessed since vaccination has become more widespread. Our study aimed to look at the impact of vaccination status on the utility of known COVID-19 severity risk factors.

Methods: The study is designed as a retrospective cohort study of encounters of admitted adult COVID-19 infected patients between May 2021 and June 2022 at a large urban academic tertiary referral hospital. Data was extracted directly from the electronic health record. Primary outcome was severe COVID-19 illness defined as having admission to the intensive care unit or escalation to the intensive care unit at any time during the hospitalization and in-hospital morality. Data on age, gender, race/ethnicity, comorbidities, and vaccination status were collected. Regardless of history of atrial fibrillation, CHA2DS2VASC score was calculated for each encounter. Each variable was associated with multivariate analysis for the primary outcomes.

Results: A total of 2960 patients with positive COVID-19 test results were included during the encounter. Of positive patients, 44.8% were females; 76.8 % were Black, and 27.1% had chronic kidney disease. Demographics are shown in Table 1.In multivariate analysis, race, obesity, CKD, CHA2DS2VASC score, and vaccination status were identified to be the key factors associated with severe COVID-19 infection. Odds ratios for severe illness were calculated for each key risk factor and are shown in Figure 1. Interestingly, vaccination status [OR 1.51, C.I. (1.25-1.82)] was the strongest predictor of severe COVID-19 infection, while CKD [OR1.33, C.I.(1.08-1.63)] emerged as the other important predictor for severity.

Conclusions: When the vaccination status is taken into consideration for evaluating the outcomes of COVID-19 infected patients, the traditionally associated risk factors are largely negated. Vaccination status and chronic kidney disease appear to be strong predictors of severe COVID-19 infection.