This is a rapid sentinel surveillance study aimed to determine what proportion of mild, outpatient influenza-like illnesses were caused by SARS-CoV-2.
This community-based surveillance study reports a 5% rate of COVID-19 among patients presented to the ED or urgent care with mild influenza-like illness.
To date diagnostic testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, has been available only through public health laboratories. Limited testing has prioritized those with severe illness or identifiable risk factors. The incidence of community transmission by persons with mild illness and without risk factors remains ill-defined.
This study examined results from 131 tests for COVID-19 obtained between March 12-13 and 15-16, 2020 at the Los Angeles County + University of Southern California Medical Center. Test were from all patients presenting to the ED or urgent care with mild influenza-like illness. Patients who had nasopharyngeal swabs tested with polymerase chain reaction assays for influenza and respiratory syncytial virus (GeneXpert Flu, Cepheid) were automatically tested for SARS-CoV-2 (Quest Diagnostics).
Of the 131 tests, 7 were positive (5.3%; 95% CI, 2.2%-10.7%). The median age of patients who tested positive was 38 years (range, 34-44 years), 3 were male (43%), and the median duration of symptoms was 4 days (range, 2-4 days). Nearly all (6 of 7 patients) presented with fever, 5 with myalgias, only 1 with cough. Only 1 patient had a travel history (returned from Miami, Florida). All patients had mild illnesses, and all tested negative for influenza and respiratory syncytial virus.