Can we use temperature measurements to identify pre‐symptomatic SARS‐CoV‐2 infection in nursing home residents?

Background COVID-19 has had a severe impact on morbidity and mortality among nursing home (NH) residents. Earlier detection of SARS-CoV-2 may position us to better mitigate the risk of spread. Both asymptomatic and pre-symptomatic transmission are common in outbreaks, and threshold temperatures, such as 38C, for screening for infection could miss timely detection in the majority of residents. We hypothesized that in long-term care residents, temperature trends with SARS-CoV-2 infection could identify infection in pre-symptomatic individuals earlier than standard screening. Methods We conducted a retrospective cohort study using electronic health records in 6176 residents of the VA NHs who underwent SARS-CoV-2 testing triggered by symptoms. We collected information about age and other demographics, baseline temperature, and specific comorbidities. We created standardized definitions, and a hypothetical model to test measures of temperature variation and compare outcomes to the VA standard of care. Results We showed that a change from baseline of 0.4C identified 47% of NH residents who became SARS-CoV-2 positive, earlier than standard testing by an average of 42.2 h. Temperature variability of 0.5C over 3 days when paired with a 37.2C temperature cutoff identified 55% of NH residents who became SARS-CoV-2 positive earlier than the standard of care testing by an average of 44.4 h. A change from baseline temperature of 0.4C when combined with temperature variability of 0.7C over 3 days identified 52% of NH residents who became SARS-CoV-2 positive, earlier than standard testing by an average of 40 h, and by more than 3 days in 22% of the residents. This earlier detection comes at the expense of triggering 57,793 tests, as compared to the number of trigger tests ordered in the VA system of 40,691. Conclusions Our model suggests that early temperature trends with SARS-CoV-2 infection may identify infection in pre-symptomatic long-term care residents.