Acute and Postacute COVID-19 Outcomes Among Immunologically Naive Adults During Delta vs Omicron Waves

• Published in: JAMA network open 2023-02, Vol.6 (2), p.e231181
• Main Authors: Doll, Margaret K, Waghmare, Alpana, Heit, Antje, Levenson Shakoor, Brianna, Kimball, Louise E, Ozbek, Nina, Blazevic, Rachel L, Mose, Larry, Boonyaratanakornkit, Jim, Stevens-Ayers, Terry L, Cornell, Kevin, Sheppard, Benjamin D, Hampson, Emma, Sharmin, Faria, Goodwin, Benjamin, Dan, Jennifer M, Archie, Tom, O'Connor, Terry, Heckerman, David, Schmitz, Frank, Boeckh, Michael, Crotty, Shane
• Format: Article
• Language: English
• Subjects: Adult; Cohort Studies; COVID-19 - epidemiology; Female; Humans; Infectious Diseases; Male; Middle Aged; Online Only; Original Investigation; Prospective Studies; SARS-CoV-2
• ISSN: 2574-3805; 2574-3805
• DOI: 10.1001/jamanetworkopen.2023.1181

The US arrival of the Omicron variant led to a rapid increase in SARS-CoV-2 infections. While numerous studies report characteristics of Omicron infections among vaccinated individuals or persons with previous infection, comprehensive data describing infections among adults who are immunologically naive are lacking. To examine COVID-19 acute and postacute clinical outcomes among a well-characterized cohort of unvaccinated and previously uninfected adults who contracted SARS-CoV-2 during the Omicron (BA.1/BA.2) surge, and to compare outcomes with infections that occurred during the Delta wave. This prospective multisite cohort study included community-dwelling adults undergoing high-resolution symptom and virologic monitoring in 8 US states between June 2021 and September 2022. Unvaccinated adults aged 30 to less than 65 years without an immunological history of SARS-CoV-2 who were at high risk of infection were recruited. Participants were followed for up to 48 weeks, submitting regular COVID-19 symptom surveys and nasal swabs for SARS-CoV-2 polymerase chain reaction (PCR) testing. Data were analyzed from May to October 2022. Omicron (BA.1/BA.2 lineages) vs Delta SARS-CoV-2 infection, defined as a positive PCR test result that occurred during a period when the variant represented at least 50% of circulating SARS-CoV-2 variants in the participant's geographic region. The main outcomes examined were the prevalence and severity of acute (≤28 days after onset) and postacute (≥5 weeks after onset) symptoms. Among 274 participants who were immunologically naive (mean [SD] age, 49 [9.7] years; 186 [68%] female; 19 [7%] Hispanic participants; 242 [88%] White participants), 166 (61%) contracted SARS-CoV-2. Of these, 137 infections (83%) occurred during the Omicron-predominant period and 29 infections (17%) occurred during the Delta-predominant period. Asymptomatic infections occurred among 7% (95% CI, 3%-12%) of Omicron-wave infections and 0% (95% CI, 0%-12%) of Delta-wave infections. Health care use among individuals with Omicron-wave infections was 79% (95% CI, 43%-92%) lower relative to individuals with Delta-wave infections (P = .001). Compared with individuals infected during the Delta wave, individuals infected during the Omicron wave also experienced a 56% (95% CI, 26%-74%, P = .004) relative reduction in the risk of postacute symptoms and a 79% (95% CI, 54%-91%, P