447. Clinical Features, Risk Factors, and Outcomes of COVID-19 in Immunocompromised Adults Hospitalized with Acute Respiratory Infection

Abstract Background Individuals with immunocompromising conditions are at high risk of severe disease from COVID-19. The objectives of this study were to describe the clinical features, risk factors, and outcomes of COVID-19 in immunocompromised (IC) adults hospitalized with acute respiratory infection (ARI). Methods We enrolled patients ≥ 18 years of age hospitalized with ARI at two Emory University hospitals from May 2021 – Aug 2022. Patient interviews and medical abstractions were completed. Nasopharyngeal and oropharyngeal swabs were tested for SARS-CoV-2 using BioFire Respiratory Panel, and results of standard-of-care testing were recorded. IC was defined using comorbidities from the medical chart (cancer, HIV, organ/stem cell/bone marrow transplant, long-term steroid use, other immunosuppressive conditions). Primary vaccination consisted of 3 mRNA or 1 J&J + 1 other dose for IC patients, and 2 mRNA or 1 J&J for non-IC patients. Vaccine effectiveness (VE) was calculated using a test-negative case-control design. Multivariable logistic regression with stepwise selection yielded a final model controlling for employment, past COVID-19, and blood disorders using SAS v9.4. Results Of 1677 enrolled participants, 1653 had SARS-CoV-2 testing, of whom 850 (50.7%) were positive and 231 (27.2% of 850) were IC. Compared to non-IC patients with SARS-CoV-2, IC patients were significantly older (median 58, IQR [44-67)), male (57.1%), and had underlying comorbidities, including blood disorders (13.9%) and chronic kidney disease (36.8%). IC patients were more commonly infected with the Omicron variant, while non-IC patients were more commonly infected with Alpha or Delta. Compared to non-IC, IC patients had longer hospitalization duration (median 4.7, IQR [2.9-9.5]), required positive-pressure ventilation (CPAP/BiPAP) (13.9%), and died (6.5%). IC patients had less commonly received a full COVID-19 vaccine series (19.9% vs. 25.8%) and adjusted VE of primary COVID-19 vaccine series against hospitalization for ARI was lower in the IC (48.7 (17.9, 68.0)) vs. non-IC patients (76.0 (68.4, 81.7)).Table 1:Vaccine Effectiveness in Immunosuppressed vs immunocompetent Conclusion Compared to non-IC hospitalized adults, COVID-19 VE against hospitalization for ARI was lower in IC patients, who were more likely to experience severe outcomes and death. Disclosures Laura A. Puzniak, PhD. MPH, Pfizer, Inc.: Employee|Pfizer, Inc.: Stocks/Bonds Robin Hubler, MS, Pfizer, Inc.: Employee|Pfizer, Inc.: Stocks/Bonds Srinivas Valluri, PhD, Pfizer Inc: Pfizer Employee and hold Pfizer stocks/options|Pfizer Inc: Ownership Interest|Pfizer Inc: Stocks/Bonds Timothy L. Wiemken, PhD, Pfizer Inc: Employee|Pfizer Inc: Stocks/Bonds Benjamin Lopman, PhD, Epidemiological Research and Methods, LLC: Advisor/Consultant|Hillevax, Inc: Advisor/Consultant Nadine Rouphael, MD, Icon, EMMES, Sanofi, Seqirus, Moderna: Advisor/Consultant Satoshi Kamidani, MD, CDC: Grant/Research Support|Emergent BioSolutions: Grant/Research Support|NIH: Grant/Research Support|Pfizer Inc: Grant/Research Support Evan J. Anderson, MD, GSK: Advisor/Consultant|GSK: Grant/Research Support|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Kentucky Bioprocessing, Inc.: Safety Monitoring Board|Moderna: Advisor/Consultant|Moderna: Grant/Research Support|Moderna: Currently an employee|Moderna: Stocks/Bonds|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant|Sanofi Pasteur: Grant/Research Support|Sanofi Pasteur: Safety Monitoring Board|WCG/ACI Clinical: Data Adjudication Board Christina A. Rostad, MD, BioFire Inc.: Grant/Research Support|GlaxoSmithKline Biologicals: Grant/Research Support|Janssen: Grant/Research Support|MedImmune LLC: Grant/Research Support|Meissa Vaccines, Inc.: RSV vaccine technology|Merck & Co., Inc.: Grant/Research Support|Micron Technology, Inc.: Grant/Research Support|Moderna, Inc.: Grant/Research Support|Novavax: Grant/Research Support|PaxVax: Grant/Research Support|Pfizer, Inc.: Grant/Research Support|Regeneron: Grant/Research Support|Sanofi Pasteur: Grant/Research Support