This study found that 21 days after a single index SARS-CoV-2 patient at Riley Hospital for Children’s dialysis center, 44% of health care workers had positive SARS-CoV-2 antibodies and 23% of patients had antibodies. 

• One week before this study began (day 0; March 25, 2020), a single patient presented with fever and generalized symptoms, who was positive for SARS-CoV-2 on PCR by nasopharyngeal swab. Pt was only dialyzed within an isolation room during this time and had repeatedly positive COVID-19 testing during the study period.
• Serum IgM and IgG levels were measured on study participants on days 7, 14, and 21 (April 1, 2020, to April 15, 2020) using SARS-CoV-2 enzyme-linked immunosorbent assays (ELISAs), with confirmatory testing at Mount Sinai Medical Center.
• 13 patients, 9 dialysis nurses, 2 nurse practitioners, 4 staff, and 10 physicians participated in the study,
• Between day 0 and day 7, 2 health care workers had negative PCR test results despite upper respiratory tract symptoms and fevers. One of these health care workers subsequently seroconverted on day 21 despite 3 negative PCR results.
• No other study participants had nasopharyngeal testing or symptomatology consistent with COVID-19 before day 7.
• No participants developed symptoms between days 7 and 21.
• No health care workers who directly cared for the PCR-positive patient seroconverted.

Summary: This was the first study of seroconversion in health care settings, and it found a high prevalence of subclinical seroconversion in individuals interacting in a pediatric dialysis unit.