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Revising Temperature Threshold Detects More COVID

January 28, 2021

Takeaway: Study findings suggest that the current fever threshold for COVID-19 screening should be reconsidered. Repeated temperature measurement with a patient-derived baseline could increase sensitivity for surveillance purposes when applied to a nursing home population. Moreover, results were presented to the Centers for Disease Control and Prevention (CDC) on May 27, 2020, and the CDC updated temperature guidance for nursing homes less than one month later.

Older people with chronic illness are at greatest risk for severe COVID-19 (SARS-CoV-2) outcomes. Threshold symptoms and signs, such as a temperature of at least 38°C (100.4°F), have been used to determine who is tested for the virus; however, an older person may have a different baseline temperature that should be considered when evaluating risk for COVID-19. HSR&D Investigator James Rudolph, MD, Director of HSR&D’s Center of Innovation in Long-Term Services and Supports for Vulnerable Veterans (LTSS) in Providence, RI, and colleagues conducted a study to compare temperature trends and to identify maximum temperatures in nursing home residents 14 days prior to and following systematic testing among Veterans residing in VA community living centers (CLCs). Using VA data from universal screening in CLCs, 453 Veterans tested positive for COVID-19. Findings also showed that:

  • A single temperature screening is unlikely to accurately detect COVID-19 in nursing home residents. Only 27% of residents who tested positive for the virus met the temperature threshold (38°C or 100.4°F) during the study period.
  • Most nursing home residents (63%) with confirmed COVID-19 experienced two or more 0.5°C elevations above their baseline temperatures.
  • There also was a group (20%) that was persistently cooler and had no temperature deviation from baseline.
  • Temperature rose above baseline nearly 1 week prior to testing positive and did not return to normal in the 2 weeks after. This temperature curve of COVID-19 may be a unique signature of the infection.

These results are part of an ongoing HSR&D-funded study (June 2020 – February 2021) that will determine the vital sign trend for Veterans residing in community living centers, individually, and as a ward, to determine whether it can effectively identify Veterans and their CLC units with and without COVID-19. More specifically, investigators are working to characterize the association between vital signs in the week prior to testing and COVID-19 positive criteria among Veterans who develop COVID. They also will identify the mortality, hospitalization, and ICU utilization rates of asymptomatic CLC residents with COVID-19 positive test results.


Research results will be used to retest for COVID-19 and trigger infection control practices that may improve outcomes. In addition, findings should provide a better understanding of patients who have COVID-19 but are asymptomatic, which has become a nation-wide public health concern. Improved understanding of the vital sign and infection relationship may provide critical guidance on how to modify infection control practices to better address the needs of CLC staff and vulnerable residents. 

Rudolph J, Halladay C, Barber M, et al. Temperature in Nursing Home Residents Systematically Tested for SARS-CoV-2. Journal of the American Medical Directors Association. Abstract published June 8, 2020.

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