About 1 in 5 patients infected with SARS-CoV-2, a new coronavirus that causes the COVID-19 disease, are also infected with other respiratory viruses, according to a preliminary analysis by the Stanford School of Medicine. In addition, the analysis found that about 1 in 10 people who exhibit symptoms of respiratory illness at an emergency department, and who are subsequently diagnosed with a common respiratory virus, are co-infected with SARS-CoV-2. The findings challenge the assumption that people are unlikely to have COVID-19 if they have another type of viral respiratory disease.
Transmission electron micrograph of SARS-CoV-2 virus particles, isolated from a patient. Image credit: NIAID.
“Currently, if a patient tests positive for a different respiratory virus, we believe that they don’t have COVID-19,” said Dr. Nigam Shah, lead author of the study.
“However, given the co-infection rates we’ve observed in this sample, that is an incorrect assumption.”
Accurate and rapid testing for SARS-CoV-2 is necessary to identify those who are infected and slow the spread of the disease.
Understanding the likelihood of co-infection is an important step in this process.
“Hospitals don’t have unlimited access to COVID testing,” said Dr. Ian Brown, co-author of the study.
“In some cases, a patient with respiratory symptoms may first be tested for a non-COVID virus.”
“If there is a diagnosis of influenza or rhinovirus, or other respiratory virus, a hospital may discharge the patient without COVID testing, concluding that the alternative diagnosis is the reason for the symptoms.”
The researchers analyzed 562 people recently tested for COVID-19 at Stanford Health Care’s Marc and Laura Andreessen Emergency Department.
Forty-nine of those people tested positive for infection with SARS-CoV-2.
Of the 562 people, 517 were also tested for the presence of other common respiratory viruses, such as influenza A and B, respiratory syncytial virus, rhinovirus, adenovirus and several types of pneumonia.
One hundred and twenty seven received a positive result for one of these other respiratory viruses.
Of the people tested for both SARS-CoV-2 and other respiratory viruses, eleven people — or about 22% of the 49 confirmed COVID-19 cases and 8.7% of the 127 people with other respiratory viruses — were found to be co-infected with both kinds of viruses.
