Early COVID-19 and Severity of Subsequent Omicron Infection in Ontario Canada.
Caroline Kassee, Altynay Shigayeva, Christopher Kandel, Lubna Farooqi, Zoe Zhong, Anne-Claude Gingras, Brenda L Coleman, Lois Gilbert, Wayne L Gold, Maria Major, Tony Mazzulli, Samira Mubareka, Srinivas Rao Valluri, Catherine Martin, Moe H Kyaw
Abstract
Open AccessWe evaluated whether having early COVID-19 reduced the severity of subsequent Omicron infection, assessing activities of daily living (ADL), healthcare utilization and illness duration. Comparisons were made between persons with (1) early COVID-19-compatible illness with a negative test, (2) early lab-confirmed SARS-CoV-2 14-26 months and (3) early lab-confirmed SAR-CoV-2 > 26 months before Omicron infection. Among 261 patients with laboratory-confirmed Omicron, 177 (68%) had COVID-19 in 2020, a median of 793 days (IQR, 659-902) prior to Omicron infection. Compared to no early COVID-19, COVID-19 14-26 months, but not > 26 months, before was associated with reduced impact on ADL during first Omicron infection (OR 0.52, 95% CI 0.29-0.93).