COVID-19 seroprevalence amongst healthcare workers: potential biases in estimating infection prevalence. (21st February 2022)

• Record Type: Journal Article
• Authors: Cordioli, Maddalena; Mirandola, Massimo; Gios, Lorenzo; Gaspari, Sebastiano; Carelli, Maria; Lotti, Virginia; Sandri, Angela; Vicentini, Caterina; Gibellini, Davide; Carrara, Elena; Tacconelli, Evelina
• Other Names: collab.
• Is Part Of: Epidemiology and infection. Volume 150(2022)
• Publication Date: 2022-02-21
• Subjects: COVID-19 -- epidemiology -- occupation-related infections; Communicable diseases -- Periodicals; Epidemiology -- Periodicals; 614.4
• DOI: 10.1017/S0950268822000280
• Languages: English
• ISSNs: 0950-2688

Abstract

Abstract: SARS-CoV-2 serological tests are used to assess the infection seroprevalence within a population. This study aims at assessing potential biases in estimating infection prevalence amongst healthcare workers (HCWs) when different diagnostic criteria are considered. A multi-site cross-sectional study was carried out in April–September 2020 amongst 1.367 Italian HCWs. SARS-CoV-2 prevalence was assessed using three diagnostic criteria: RT-PCR on nasopharyngeal swab, point-of-care fingerprick serological test (POCT) result and COVID-19 clinical pathognomonic presentation. A logistic regression model was used to estimate the probability of POCT-positive result in relation to the time since infection (RT-PCR positivity). Among 1.367 HCWs, 69.2% were working in COVID-19 units. Statistically significant differences in age, role and gender were observed between COVID-19/non-COVID-19 units. Prevalence of SARS-CoV-2 infection varied according to the criterion considered: 6.7% for POCT, 8.1% for RT-PCR, 10.0% for either POCT or RT-PCR, 9.6% for infection pathognomonic clinical presentation and 17.6% when at least one of the previous criteria was present. The probability of POCT-positive result decreased by 1.1% every 10 days from the infection. This study highlights potential biases in estimating SARS-CoV-2 point-prevalence data according to the criteria used. Although informative on infection susceptibility and herd immunity level, POCT serological tests are not the best predictors of previous COVID-19 infections for public health monitoring programmes.