273. Emergence of the SARS-CoV-2 Omicron Variant in the Pragmatic Assessment of Influenza Vaccine Effectiveness in the Department of Defense (PAIVED) Study

Abstract Background Novel SARS-CoV-2 (SCV2) variants may differ in epidemiology and clinical impact. PAIVED, a randomized trial comparing the efficacy of 3 different platforms inactivated influenza vaccines adult military health system beneficiaries, actively surveils participants for influenza-like illness (ILI), including COVID-19, conducts targeted investigations among those who develop ILI. The current season (2021/22) offered an opportunity to assess symptomatology associated with emerging SCV2 this prospective cohort. Methods Following receipt vaccine, PAIVED receive weekly email or text message querying ILI symptoms. Those reported completed validated symptom diary (FLU-PRO Plus) daily 7 days collected nasal swab. Nasal specimens underwent multiplex PCR testing, followed by genome sequencing as applicable. study from 2021-22 ILI, had confirmed infection which sequence data is available, at least one FLU-PRO Plus survey were included analysis. Results To date, 293 (7% active cohort; 22.5% reporting ILI) tested positive SCV2; has identified 23 Delta 200 Omicron (199 BA.1, 1 BA.2). Among 212 sequenced data, 55% male, 57% white, 85% active-duty (Table 1). Overall, peak severity was classified mild moderate 79.3% cases, fever duration averaged 2.5±2.2 days, there activity limitations mean 5.2±3.8 days. No differences maximum scores (total domain) detected infected compared Delta. Figure depicts variation day grouped variant. Table 1.Demographic characteristics during 2021/22 season.Figure 1.Mean domain total since identification PAIVED. Conclusion emerged predominant variant causing our cohort season, typically manifesting Further exploration potential experience between other causes, plus impact timing vaccination, will add insight into relative contribution such factors on symptomatology. Disclosures John H. Powers, III, MD, Arrevus: Advisor/Consultant|Eicos: Advisor/Consultant|Evofem: Advisor/Consultant|Eyecheck: Advisor/Consultant|Gilead: Advisor/Consultant|GlaxoSmithKline: Advisor/Consultant|OPKO: Advisor/Consultant|Resolve: Advisor/Consultant|Romark: Advisor/Consultant|SpineBioPharma: Advisor/Consultant|UTIlity: Advisor/Consultant|Vir: Advisor/Consultant Jitendrakumar Modi, GlaxoSmithKline: I am paid speaker GSK. do not speak their flu brand. Timothy Burgess, MPH, AstraZeneca: HJF, support USU IDCRP, funded conduct augment unrelated Phase III Mab vaccine trials part US Govt. COVID19 response.