New research suggests that the common cold may help prevent the spread of the flu and other respiratory viruses.
Over the past decade, advancements in the detection of viral respiratory infections have allowed the ability to better diagnose these types of infections. Further, these diagnostic test results provide valuable information that can be used to understand and study the underlying mechanisms of how viral respiratory infections spread.
Viral interference, in which being infected with one virus can provide temporary protection against being infected with other viruses, is one such proposed mechanism of how respiratory viruses behave and could explain how the common cold may help prevent the spread of the flu.
The way viral interference works gained interest during the 2009 H1N1 pandemic, when data from European countries showed that the expected spread of the H1N1 swine flu was delayed or reduced because of the circulation of the common cold during the fall season. One study revealed that co-infection with two different respiratory viruses at the same time was low.
Researchers in the United States performed an experimental infection study of the rhinovirus (common cold) and influenza A virus to further understand co-infection behaviours of these two respiratory viruses. Their results were published in The Lancet Microbe.
The researchers collected respiratory cell samples from healthy adults and grew them in the lab. They then infected some of the cells with the common cold virus. After giving the infected cells time to incubate, the cells were then also introduced to the influenza A virus. The researchers assessed how cells with previous exposure to the common cold responded versus how cells without previous exposure responded to the influenza A virus.
The researchers found that previous exposure to the common cold virus limited the ability of the influenza A virus to infect the cells through antiviral defense mechanisms that were activated by the infection with the common cold. These results are consistent with findings from previous observations of low respiratory virus co-detection rates in patients.
While it is difficult to predict how one respiratory virus may affect the infection behaviour of another respiratory virus, this study provides evidence of how the common cold may help prevent the spread of the flu. It can also be used to support future studies that investigate the phenomenon of viral interference and play a role in interrupting epidemics.
Importantly, in the context of the current pandemic, the researchers are now beginning to study whether the common cold can also affect the infectious ability and behaviour of the SARS-CoV-2 virus that causes COVID-19.
Written by Maggie Leung, PharmD
References
- Wu, A., Mihaylova, V. T., Landry, M. L., & Foxman, E. F. (2020). Interference between rhinovirus and influenza A virus: A clinical data analysis and experimental infection study. The Lancet Microbe. doi:10.1016/s2666-5247(20)30114-2
