Serologic SARS-CoV-2 Testing in Healthcare Workers with Positive RT-PCR Test or Covid-19 Related Symptoms

Author(s): Giovanni Visci, Vittorio Lodi, Roberta Bonfiglioli, Tiziana Lazzarotto, Francesco S. Violante, Paolo Boffetta.

Background: Limited information is available on prevalence and determinants of serologic response to SARS-CoV-2 infection among healthcare workers (HCWs).


Methods: We analyzed the results of serologic testing with chemiluminescence immunoassay analyzer (CLIA), lateral flow immunoassay (LFIA) and enzyme-linked immunosorbent assay (ELISA) test among 544 HCWs with at least one positive RT-PCR test and 157 HCWs with Covid-19 related symptoms without a positive RT-PCR test from public hospitals in Bologna, Northern Italy. Tests were performed between March and August 2020. We fitted multivariate logistic regression models to identify determinants of positive serology.

Results: The sensitivity of SARS-CoV-2 was 75.2% (LFIA) and 90.6% (CLIA). No differences in seropositivity were observed by sex, while older HCWs had higher positivity than other groups, and nurses had higher positivity compared to physicians, but not other HCWs. An estimated 73.4% of HCWs with Covid-19 symptoms without RT-PCR test were not infected with SARS-CoV-2.

Conclusions: Our study provides the best available data on sensitivity of serologic tests and on determinants of serologic response among HCWs positive for SARS-CoV-2, and provide evidence on the low specificity of Covid-19 related symptoms to identify infected HCWs.

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