Research published by scientists at the University of Glasgow found that rhinovirus, which causes the common cold, triggers an immune response that appears to block SARS-CoV-2 replicating in cells of the respiratory tract.
Further mathematical calculations studies showed that this virus-virus interaction could have a population-wide effect and that an increasing prevalence of rhinovirus could reduce the number of new Covid-19 cases.
Human rhinoviruses cause the common cold and are the most widespread respiratory viruses found in people.
Previous research has shown that interactions between rhinoviruses and other respiratory viruses can affect the type and severity of infections in individuals, and the way in which they infect and circulate around groups of people.
Viruses only infect a small number of cell types within the body, and respiratory viruses typically infect cells within the respiratory tract.
Professor Pablo Murcia, from the MRC-University of Glasgow Centre for Virus Research, said: “Our research shows that human rhinovirus triggers an innate immune response in human respiratory epithelial cells which blocks the replication of the Covid-19 virus, SARS-CoV-2.
“This means that the immune response caused by mild, common cold virus infections, could provide some level of transient protection against SARS-CoV-2, potentially blocking transmission of SARS-CoV-2 and reducing the severity of Covid-19.
“The next stage will be to study what is happening at the molecular level during these virus-virus interactions, to understand more about their impact on disease transmission.
“We can then use this knowledge to our advantage, hopefully developing strategies and control measures for Covid-19 infections.
“In the meantime, vaccination is our best method of protection against Covid-19.”
For their study – published in the Journal of Infectious Diseases on Tuesday and led by scientists at the MRC-University of Glasgow Centre for Virus Research (CVR) – the researchers first infected human respiratory cells with SARS-CoV-2 in the lab, recreating the cellular environment in which infections normally occur.
They then studied the replication of SARS-CoV-2 in these cells, both in the presence and absence of rhinovirus.
The study, ‘Human rhinovirus infection blocks SARS-CoV-2 replication within the respiratory epithelium: implications for COVID-19 epidemiology’, was funded by the Medical Research Council.