A case study of a patient with multiple symptoms compatible with COVID-19, a history of potential exposure to a positive case, and 4 negative nasopharyngeal swabs with later confirmation of COVID-19 illustrates the challenges that can occur in diagnosing this disease. The article is published in CMAJ (Canadian Medical Association Journal).

Testing for COVID-19 is not always straightforward, as the sampling technique and timing within the clinical course can influence diagnostic sensitivity.

A 76-year-old man who had a potential exposure to COVID-19 in a classroom, presented to hospital with a 6-day history of progressive respiratory symptoms, fatigue and an episode of fainting. Yet, an outpatient nasopharyngeal swab for COVID-19 was negative. He underwent 3 further nasopharyngeal swabs in hospital, which were also negative, and required invasive mechanical ventilation for worsening oxygen requirements. Bronchoscopy conducted 6 days after admission was positive for SARS-CoV-2 infection.

The authors note that he may have acquired the disease in hospital, perhaps from asymptomatic health care workers, which highlights the need for universal precautions in patient care.

“The early identification of patients with COVID-19 is crucial to starting appropriate isolation and management. Our case illustrates some diagnostic challenges for COVID-19 and the resulting implications for infection management, including the control of nosocomial [hospital] transmission,” writes Dr. Divjot Kumar, a respirology fellow with the Division of Respiratory Medicine, University of British Columbia, Vancouver, BC, with coauthors.

“SARS-CoV-2 infection in a 76-year-old man with negative results for nasopharyngeal swabs and possible nosocomial transmission” is published April 24, 2020.