Common Cold Infection May Trigger Antiviral Defenses Against Influenza


A study evaluated interference between rhinovirus and influenza A virus during the 2009 pandemic.


New research suggests that infection with the common cold may jumpstart the body’s antiviral defenses, therefore decreasing the likelihood of becoming infected with the flu virus.

The findings, published in The Lancet Microbe, reported an interference between rhinovirus and influenza A virus (IAV) during the 2009 H1N1 swine flu pandemic, indicating that the spread of IAV may have been disrupted by the annual autumn rhinovirus epidemic.1

For the study, investigators analyzed clinical data to examine the co-occurrence of rhinovirus and IAV in respiratory specimens from adults aged 21 years and older at Yale-New Haven Hospital over 3 consecutive winter seasons. Between July 2016 and June 2019, the investigators examined a total of 8284 respiratory samples positive for either rhinovirus or IAV to establish the period of peak virus co-circulation between November and March.1

According to the results, there were 989 rhinovirus and 922 IAV detections during this time, with a significantly lower than expected odds of co-detection. Additionally, the investigators reported that, once the cell culture was exposed to the rhinovirus, it remained protected against IAV infection 3 days later.1

According to study investigator Ellen Foxman, MD, PhD, these antiviral defenses were already triggered before the flu virus arrived. The presence of rhinovirus turned on the production of the antiviral agent interferon, which is part of the early immune system response to invasion of pathogens, Foxman said in a press release about the findings.2

Overall, the results suggest that viral interference can potentially affect the course of an epidemic, the investigators concluded.1 However, Foxman noted that it is still unclear as to whether the annual seasonal spread of the common cold will have a similar effect on infection rates for those exposed to the coronavirus disease 2019 (COVID-19).2

“It is impossible to predict how 2 viruses will interact without doing the research,” she said.2

Foxman said that her lab has begun to study whether the introduction of the common cold virus before COVID-19 infection might have similar effects.2

This study was primarily funded by the National Institutes of Health and the National Institutes of General Medical Sciences.


  1. Wu A, Mihaylova VT, Landry ML, Foxman EF. Interference between rhinovirus and influenza A virus: a clinical data analysis and experimental infection study. The Lancet Microbe. 2020. Doi:
  2. Common cold combats influenza. News release. Yale; September 4, 2020. Accessed September 18, 2020.

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