medRxiv. 2020 Aug 5:2020.07.31.20166066. doi: 10.1101/2020.07.31.20166066. Preprint.
IMPORTANCE: Current evidence suggests that transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is possible among symptom-free individuals but limited data are available on this topic in healthcare workers (HCW). The quality and acceptability of self-collected nasopharyngeal swabs (NPS) is unknown.
OBJECTIVE: To estimate the prevalence of SARS-CoV-2 infection and to assess the acceptability of self-collected NPS among HCW.
DESIGN: Cross-sectional convenience sample enrolled between April 20th and June 24th, 2020. We had >95% power to detect at least one positive test if the true underlying prevalence of SARS-CoV2 was > 1%.
SETTING: The metropolitan area surrounding Minneapolis and St. Paul, Minnesota.
PARTICIPANTS: HCW free of self-reported upper respiratory symptoms were recruited. Exposures: Participants completed questionnaires regarding demographics, household characteristics, personal protective equipment (PPE) utilization and comorbidities.
OUTCOMES: A participant self-collected nasopharyngeal swab (NPS) was obtained. SARS-CoV-2 infection was assessed via polymerase chain reaction. NPS discomfort was assessed on a scale of 1 (no discomfort) - 10 (extreme discomfort). NPS duration and depth into the nasopharynx, and willingness to perform future self-collections were assessed.
RESULTS: Among n=489 participants 80% were female and mean age+/-SD was 41+/-11. Participants reported being physicians (14%), nurse practitioners (8%), physicians assistants (4%), nurses (51%), medics (3%), or other which predominantly included laboratory technicians and administrative roles (22%). Exposure to a known/suspected COVID-19 case in the 14 days prior to enrollment was reported in 40% of participants. SARS-CoV-2 was not detected in any participant. The mean+/-SD discomfort level of the NPS was 4.5+/-2.0. 95% of participants reported that their self-swab was longer than or equal to the duration of patient swabs they had previously performed, and 89% reported the depth to be deeper than or equal to the depth of previous patient swabs. Over 95% of participants reported a willingness to repeat a self-collected NP swab in the future.
CONCLUSIONS AND RELEVANCE: The point prevalence of SARS-CoV-2 infection was likely very low in symptom-free Minnesota healthcare workers from April 20th and June 24th, 2020. Self-collected NP swabs are well-tolerated and a viable alternative to provider-collected swabs to preserve PPE.