Prevalence of ongoing or previous SARS-CoV-2 infection among dental personnel - the Swedish experience

Objective To investigate whether personnel in a public dental clinic had a higher frequency of ongoing or previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection than hospital healthcare workers or the general public in Stockholm during weeks 23-25 in 2020. Materials and methods We carried out an observational cohort study from March to June 2020, including 341 employees randomly selected from Public Dental Service in the County of Stockholm. The primary outcome variable was the prevalence of SARS-CoV-2 RNA and/or antibodies against SARS-CoV-2. Throat samples were analysed for SARS-CoV-2 RNA. Venous blood was collected to detect antibodies against SARS-CoV-2 using the Luminex analysis tool (immunoassay) and ELISA. Logistic regression analysis was used to compare the independent groups and calculate the unadjusted odds ratio. Results The mean age of the participants was 50.1 years, and 11.7% were male. The prevalence of SARS-CoV-2 RNA and/or antibodies against SARS-CoV-2 was 12.0% (95% confidence interval 8.8-16.0). Among them, 82.5% reported symptoms and 85.4% were on sick-leave between March and June 2020. Conclusions The seroprevalence of SARS-CoV-2 infection was approximately similar to that in healthcare personnel, and approximately equal compared to that in the general population.