Risk Factors for Long COVID among Healthcare Workers, Brazil, 2020

Objectives: We aimed to determine risk factors for the development of long coronavirus disease (COVID) in healthcare workers (HCWs). Methods: We conducted a case-control study among HCWs who had confirmed COVID-19 infection working in a Brazilian healthcare system between March 1, 2020 and July 15, 2022. Cases were defined as those having long COVID per the Centers for Disease Control and Prevention definition. Controls were defined as HCWs who had documented COVID-19 infection but did not develop long COVID. Multiple logistic regression was used to assess the association between exposure variables and long COVID during 180 days of follow-up. Results: Of 7,051 HCWs diagnosed with COVID-19 infection, 1,933 (27.4%) who developed long COVID were compared to 5,118 (72.6%) who did not. The majority of those with long COVID (51.8%) had 3 or more symptoms. Factors associated with development of long COVID were female sex (OR 1.21 [CI95 1.05-1.39]), age (OR 1.01 [CI95 1.00-1.02]), and two or more COVID-19 infections (1.27 [CI95 1.07-1.50]). Those infected with the Delta variant (OR 0.30 [CI95 0.17-0.50]) or the Omicron variant (OR 0.49 [CI95 0.30-0.78]), and those receiving four COVID-19 vaccine doses prior to infection (OR 0.05 [CI95 0.01-0.19]) were significantly less likely to develop long COVID. Conclusions: Long COVID can be prevalent among HCWs. We found that acquiring more than one COVID-19 infection was a major risk factor for long COVID, while maintenance of immunity via vaccination was highly protective.