Impact of Fever Thresholds in Detection of COVID-19 in Department of Veterans Affairs Community Living Center residents

Taissa Bej MS; Sonya Kothadia MD, MS; Brigid M. Wilson PhD; Sunah Song MS; Janet M. Briggs RN, NP; Richard E. Banks BS; Curtis J. Donskey MD; Federico Perez MD, MS; Robin L. P. Jump MD, PhD


J Am Geriatr Soc. 2021;69(11):3044-3050. 

In This Article


Between March 1 and November 30 2020, 10,351 of 11,908 (87%) CLC residents tested for SARS-CoV-2 had negative results (Table 1). The positivity rate was 13% or 130.8 cases per 1000 residents. Most of the residents were male (96%) with a mean age of 74.1 (±10.7) years and a high burden of chronic medical conditions with a mean CCI of 4.85 (±3.4). Of the 1557 who tested positive, 321 (21%) were symptomatic, 425 (27%) were pre-symptomatic, and 811 (52%) remained asymptomatic. All of the 425 residents who were pre-symptomatic at the time of testing went on to develop a temperature of >100.4°F. Statistical analysis did not detect differences among the CCI for CLC residents with a negative SARS-CoV-2 test and those with symptomatic, pre-symptomatic, and asymptomatic COVID-19 infection.

Overall, COVID-19 infection resulted in 22.6 deaths per 1000 residents at VA CLCs. All-cause mortality at 30 days was highest among CLC residents with pre-symptomatic infections (26%), followed by those with symptomatic infections (24%), without a statistically significant difference between the survival curves for these two groups (Figure 1). Those with asymptomatic infections had a higher survival rate, with a 30-day mortality of 10%, compared with 5% observed among residents with a negative SARS-CoV-2 test (p < 0.001).

Figure 1.

Kaplan–Meier curves of time to death among all Community Living Center residents screened for SARS-CoV-2, stratified by test results and symptoms based on a fever threshold of >100.4°F

Using the lower temperature threshold (>99.0°F) to assess fever at the time of testing would have changed the categorization of 46% (195/425) of pre-symptomatic and 32% (257/811) of asymptomatic residents to symptomatic. This would have increased the number of residents recognized as symptomatic at the time of their positive SARS-CoV-2 test from 321 to 773. The number of residents with a negative SARS-CoV-2 test deemed to have a fever would have also increased, from 535 (with >100.4°F) to 2469 (with >99.0°F). All-cause mortality was similar among groups when residents were categorized using the lower temperature threshold. Mortality remained the highest for those who would have been symptomatic (20%), followed by pre-symptomatic (18%), and asymptomatic (8%). In our cohort of CLC residents, a temperature of >100.4°F as a threshold to consider testing for SARS-CoV-2 resulted in a sensitivity and specificity of 21% and 93%, respectively (Figure 2). Lowering the temperature threshold to >99.0°F changed the sensitivity and specificity to 50% and 72%, respectively.

Figure 2.

Influence of temperature thresholds when screening Community Living Center residents for COVID-19 infection. Two-by-two contingency tables and resulting sensitivity and specificity when using a temperature of >100.4°F (panel A) or >99.0°F (panel B) to prompt consideration for SARS-CoV-2 testing