Nearly 1 in 5 coronavirus patients are also infected with other respiratory viruses, find US scientists
About 1 in 5 people with COVID-19 are also infected with other respiratory viruses. Besides, 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 the COVID-19 virus, say researchers from the Stanford University School of Medicine, California. The findings challenge the assumption that people are unlikely to have COVID-19 if they have another type of viral respiratory disease, say experts.
Early in the COVID-19 pandemic, reports from China indicated that the co-infection of the novel coronavirus and other respiratory pathogens was uncommon, suggesting that patients who tested positive for other pathogens could be assumed to not have the novel coronavirus. However, that is an incorrect assumption given the co-infection rates observed in the new analsysis, caution experts. The US Centers for Disease Control and Prevention (CDC) had also recommended testing for other respiratory pathogens, saying that confirmation could help rule out COVID-19 amid the lack of widely available testing.
The researchers from Stanford initially analyzed 562 people who were 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, the virus that causes COVID-19. 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. The analysis shows that 127 received a positive result for one of these other respiratory viruses.
Of the 49 positive SARS-COV-2 results, 11 (22.4%) also had a co-infection. Of the 127 positives for other viruses, 11 (8.66%) had a SARS-COV-2 co-infection. These co-infection rates are much higher than previously reported rates, the team emphasizes.
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, the team explains.
Experts report 21% COVID-19 co-infection rate
The research was also done using a bigger sample size. The experts found that rates of COVID-19 co-infections with other respiratory pathogens were 21%, higher than previously thought. “We studied 1,217 specimens tested for SARS-CoV-2 and other respiratory pathogens, from 1,206 unique patients,” says the research letter published in JAMA.
The Stanford University team performed tests for COVID-19 and other respiratory pathogens on the nose and throat swabs from 1,206 symptomatic patients from multiple sites in northern California from March 3 to 25. “Some sites tested the specimens for COVID-19 as well as influenza A and B, respiratory syncytial virus (RSV), non-COVID-19 coronaviruses, adenovirus, parainfluenza 1 through 4, human metapneumovirus, rhinovirus/enterovirus, Chlamydia pneumonia, and Mycoplasma pneumonia,”
The researchers found that 116 of the 1,217 specimens (9.5%) were positive for SARS-CoV-2 and 318 (26.1%) were positive for 1 or more non-SARS-CoV-2 pathogens. A detailed analysis shows that of the 116 specimens that tested positive for COVID-19, 24 (20.7%) were positive for at least one other pathogen, versus 294 of the 1,101 specimens (26.7%) negative for the novel coronavirus.
The most common co-infections included rhinovirus/enterovirus (6.9%), RSV (5.2%), and non-COVID-19 coronaviruses (4.3%). None of the differences in rates of non-COVID-19 pathogens between specimens positive and negative for the novel coronavirus was statistically significant, say experts.
Of 318 samples positive for at least one pathogen that was not SARS-CoV-2, 24 (7.5%) were also positive for the novel coronavirus. Of 899 samples negative for other pathogens, 92 (10.2%) were positive for SARS-CoV-2. Patients with co-infections did not differ significantly in age (mean, 46.9 years) from those infected with SARS-CoV-2 only (mean, 51.1 years), the findings reveal.
“These results suggest higher rates of co-infection between SARS-CoV-2 and other respiratory pathogens than previously reported, with no significant difference in rates of SARS-CoV-2 infection in patients with and without other pathogens. The presence of a non-SARS-CoV-2 pathogen may not provide reassurance that a patient does not also have SARS-CoV-2,” says researchers. They add, “These results indicate that routine testing for non–SARS-CoV-2 respiratory pathogens during the COVID-19 pandemic is unlikely to provide clinical benefit unless a positive result would change disease management.”
Co-infections can be potentially lethal
Despite the proven importance of co-infections in the severity of respiratory diseases, they are understudied during large outbreaks of respiratory infections such as the coronavirus pandemic, warn experts. Diagnosing co-infections is complex: the organism itself might be carried by the patient before the viral infection, might be part of an underlying chronic infection, or might be picked up nosocomially (hospital-acquired infections), they explain.
“Respiratory viral infections predispose patients to co-infections and these lead to increased disease severity and mortality. Most fatalities in the 1918 influenza outbreak were due to subsequent bacterial infection, particularly with Streptococcus pneumonia. Poor outcomes in the 2009 H1N1 influenza pandemic were also associated with bacterial co-infections, although few studies captured these data,” write UK experts from the University of Birmingham, University of Edinburgh, and University of East Anglia, Norwich, in The Lancet.
Accordingly, the experts recommend that “rapid characterization of coinfection” is essential in the management and treatment of the most severe COVID-19 cases, and could help to save lives.
Globally, over 3,519,900 cases of COVID-19 has been reported as of May 4, and more than 247,530 have died in the pandemic, according to the Johns Hopkins tracker.