Can COVID-19 coinfect with other viruses like flu?

Can COVID-19 coinfect with other viruses like flu?

Last Reviewed : 12/16/2020
Can COVID-19 coinfect with other viruses like flu?

As COVID-19 pandemic started during flu season and as flu symptoms and COVID-19 symptoms are very similar, there has been a concern if both viruses can coinfect. When the COVID-19 pandemic first started, the possibility of flu and COVID-19 coinfection was considered to be very low. Once Influenza test was positive in an individual, there were no recommendations to test for COVID-19. In fact, several healthcare facilities were testing for Influenza first and they would test for COVID-19 only if the influenza test came back negative. As the pandemic got worse and as there were more cases all across the globe, the picture got clearer and recommendations slowly started changing.

A study published in Emerging Infectious Diseases Journal reported COVID-19 coinfection with influenza virus in a patient with pneumonia in China. This is the first study that reported that coinfection can happen with COVID-19 and other respiratory viruses. It questioned the sensitivity or the ability of the test to detect Novel Coronavirus. It also raised concerns about underdiagnosing COVID-19 infections because of false-negative tests for upper respiratory specimens.

According to another study published in the Journal of Medical Virology, among 115 patients confirmed with COVID-19, 5 patients were also diagnosed with influenza virus infection. The study described clinical characteristics of these 5 patients who had both influenza and coronavirus infection. They all had fever, cough, and shortness of breath. Three patients had sore throat, two patients had body aches, and two patients had fatigue. These are the same symptoms that may be seen in patients only with COVID-19 or only with influenza infection. None of these five patients needed ICU level of care and there were no deaths. The study concluded that patients with COVID-19 may have coinfection with the influenza virus or vice versa. Patients with both COVID-19 and influenza virus infection did not appear to have a more severe condition.

Based on these studies, it is evident that COVID-19 may coinfect with other respiratory viruses like influenza. More research may be needed to identify the extent of the coinfection and its potential consequences. We may also need more guidelines regarding when to test for coinfection and if treatment for coinfected patients should be any different. As pandemic progresses, we may have answers for these questions.



  1. AU Wu X et al. Co-infection with SARS-CoV-2 and Influenza A Virus in Patient with Pneumonia, China. Emerg Infect Dis. 2020;26(6) Epub 2020 Mar 11.
  2. AU Ding Q et al. The clinical characteristics of pneumonia patients co-infected with 2019 novel coronavirus and influenza virus in Wuhan, China. J Med Virol. 2020.

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