Are presymptomatic SARS-CoV-2 infections in nursing home residents unrecognized symptomatic infections? Sequence and metadata from weekly testing in an extensive nursing home outbreak

Judith H van den Besselaar, Reina S Sikkema, Fleur M H P A Koene, Laura W van Buul, Bas B Oude Munnink, Ine Frénay, René Te Witt, Marion P G Koopmans, Cees M P M Hertogh, Bianca M Buurman

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BACKGROUND: Sars-CoV-2 outbreaks resulted in a high case fatality rate in nursing homes (NH) worldwide. It is unknown to which extent presymptomatic residents and staff contribute to the spread of the virus.

AIMS: To assess the contribution of asymptomatic and presymptomatic residents and staff in SARS-CoV-2 transmission during a large outbreak in a Dutch NH.

METHODS: Observational study in a 185-bed NH with two consecutive testing strategies: testing of symptomatic cases only, followed by weekly facility-wide testing of staff and residents regardless of symptoms. Nasopharyngeal and oropharyngeal testing with RT-PCR for SARs-CoV-2, including sequencing of positive samples, was conducted with a standardized symptom assessment.

RESULTS: 185 residents and 244 staff participated. Sequencing identified one cluster. In the symptom-based test strategy period 3/39 residents were presymptomatic versus 38/74 residents in the period of weekly facility-wide testing (p-value<0.001). In total, 51/59 (91.1%) of SARS-CoV-2 positive staff was symptomatic, with no difference between both testing strategies (p-value 0.763). Loss of smell and taste, sore throat, headache or myalga was hardly reported in residents compared to staff (p-value <0.001). Median Ct-value of presymptomatic residents was 21.3, which did not differ from symptomatic (20.8) or asymptomatic (20.5) residents (p-value 0.624).

CONCLUSIONS: Symptoms in residents and staff are insufficiently recognized, reported or attributed to a possible SARS-CoV-2 infection. However, residents without (recognized) symptoms showed the same potential for viral shedding as residents with symptoms. Weekly testing was an effective strategy for early identification of SARS-Cov-2 cases, resulting in fast mitigation of the outbreak.

Original languageEnglish
JournalAge and Ageing
Publication statusE-pub ahead of print - 7 May 2021

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