Weekly SARS-CoV-2 Testing Effective for Fast Mitigation of NH Outbreak

Incorporating weekly facility-wide testing for SARS-CoV-2 in a 185-resident nursing home identified 38 residents who were presymptomatic up to 8 days before symptoms occurred, according to a study of a large SARS-CoV-2 outbreak in a Dutch nursing home. Researchers published their findings online ahead of print in Age and Ageing. 

“Weekly testing was an effective strategy for early identification of SARS-CoV-2 cases, resulting in fast mitigation of the outbreak,” they wrote. 

The observational study looked at two consecutive testing strategies of 185 residents and 244 staff members at a single nursing home: testing of symptomatic individuals only, and weekly facility-wide testing of individuals regardless of symptoms.  

During the period when only individuals with symptoms were tested, 3 of 39 residents were presymptomatic, according to the study, compared with 38 of 74 residents during the period of weekly facility-wide testing.  

Although 91.1% staff who tested positive for SARS-CoV-2 were symptomatic, subjective symptoms such as loss of smell and taste, sore throat, headache, or myalgia were rarely reported in residents, the study found.  

“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),” researchers reported. 

For staff, there was no difference between testing strategies. 

“The absence of subjective symptoms (such as loss of smell or taste) in residents compared to staff who are infected by the same SARS-CoV-2 strain suggests the underreporting of symptoms in residents,” researchers wrote in an uncorrected manuscript of the study posted on the journal website. “As such, it is not possible to make a distinction between a/presymptomatic and unrecognized symptomatic residents in this study. However, a/presymptomatic residents have the same high viral load as symptomatic residents, which suggests the same potential for viral shedding.” 

The study’s findings support guidelines to test residents and staff regardless of symptoms to identify individuals with SARS-CoV-2 earlier and reduce spread, researchers stated.  

—Jolynn Tumolo

Reference:

van den Besselaar JH, Sikkema RS, Koene FMHPA, et al. 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 [published online ahead of print, 2021 May 7]. Age Ageing. 2021;afab081. doi:10.1093/ageing/afab081