You'd have to be particularly unlucky to
catch a cold and the flu at the same time, a new study finds.
Catching a cold when you already have the flu
sounds like a nightmare scenario. But fortunately, this doesn't happen very
often, a new study finds.
Indeed, the researchers found that having the
flu actually reduces a person's chances of developing an infection with a
common cold virus.
"What we found is that during certain
seasons when you have high levels of circulation of influenza, you are less
likely to catch a cold caused by a rhinovirus [the main cause of colds],"
said study lead author Dr. Pablo Murcia, a senior lecturer at the MRC-Centre
for Virus Research at the University of Glasgow in Scotland, said in a video
about the study. This finding was true at both the population level (meaning
across the population as a whole) and the individual level (meaning within an
individual person).
Researchers typically study cold and flu
viruses separately, "but we've shown here that we need to also be studying
these viruses together like it's an ecosystem," Murcia said in a
statement. "If we understand how viruses interact and how certain viral
infections may favor or inhibit each other, then maybe we can develop better
ways to target viruses."
More flu,
less colds
In the new study, the researchers analyzed
information from more than 36,000 individuals in Scotland who provided more
than 44,000 throat and nose swabs for testing for respiratory illnesses over a
nine-year period. These samples were tested for 11 types of respiratory
viruses, such as rhinoviruses, influenza A and B viruses, respiratory syncytial
virus and adenoviruses.
In this population, 35% tested positive for
at least one virus, and 8% tested positive for co-infection with at least two
viruses.
Interestingly, a computer analysis of the
data showed that when flu activity picked up in the winter, infections with
rhinoviruses decreased.
"One really striking pattern in our data
is the decline in cases of the respiratory virus rhinovirus ... occurring
during winter, around the time that flu activity increases," said study
first author Sema Nickbakhsh, a research associate at the Centre for Virus
Research.
What's more, when the researchers looked at
individual patients, they found that people infected with influenza A were 70%
less likely to also be infected with rhinovirus, compared with patients
infected with other types of viruses.
Competing viruses
The new study cannot determine the reason for
the inhibitory effect between flu viruses and rhinovirus. But the researchers
have a theory — these viruses may be in competition with each other in their
quest to replicate and cause you misery.
"We believe respiratory viruses may be
competing for resources in the respiratory tract," Nickbakhsh said. It may
be that these viruses compete for specific cells to infect, or that a person's
immune response to one virus makes it harder for the other virus to also cause
infection, she said.
And there could be other factors at play,
such as people staying at home when they are sick, which may reduce the chances
of catching another virus.
More studies are needed to better understand the biological mechanisms underlying these virus-virus interactions, the authors said.
.png)
.jpg)
.gif)
