Clinical Question

How likely are long COVID symptoms to occur among fully vaccinated health care workers after infections that did not require hospitalization?

Bottom Line

Among health care workers, the study found that long COVID is less likely in those who have been infected with more recent variants of COVID-19 and in those who have received three doses of the COVID-19 vaccine. (Level of Evidence = 1b)

Synopsis

The study took place in a network of nine Italian hospitals from March 2020 to April 2022. Personnel were tested weekly, every other week, or any time they developed symptoms using polymerase chain reaction for SARS-CoV-2. Long COVID was defined as the persistence of a symptom for more than four weeks after the acute infection. Over the study period, 739 of 2,560 personnel tested positive for COVID-19 (89 were asymptomatic) and 229 (31%) developed long COVID. The prevalence of long COVID differed by variant: 42% for the ancestral strain, 36% for the alpha variant, and 16% for the delta or omicron variants. The group at highest risk was unvaccinated women. In a multivariate analysis, the risk was lower for men (adjusted odds ratio = 0.65; 95% CI, 0.44 to 0.98), people who received two vaccine doses (adjusted odds ratio = 0.25; 95% CI, 0.07 to 0.87), and people who received three vaccine doses (adjusted odds ratio = 0.16; 95% CI, 0.03 to 0.84). The risk of long COVID increased with older age, in people with allergies, and in people with an increasing number of comorbidities. The illness trajectory for patients with long COVID (i.e., duration and severity of symptoms over time) was not reported.