From April 22 to April 30, 2020, every employee except for symptomatic (quarantined) staff, at Hospital East-Limburg were invited for SARS-CoV-2 antibody testing.

A single-lane rapid IgG/IgM lateral flow assay directed to the nucleocapsid protein of SARS-CoV-2 (COVID-19 IgG/IgM Rapid Test Cassette; Multi-G) was used. Because of inadequate performance, IgM results were excluded.

Demographic characteristics and job title were obtained from human resources records. Staff were asked to complete a survey on exposure risks (patient, coworker, and household contact) and symptoms from March 1.