Here's a weird problem. Remember it's weird. If you could choose between being infected with the flu virus and the cold virus, which virus would you select?

The first thing that probably popped into your mind is, "Are you crazy?" Followed by, "Who wants to get sick, anyway?" And you didn't bother to answer the question, did you?

A medical study conducted by expert virologists actually looked into this question and the answer isn't the first thing that popped into your mind. Conducted by the MRC-Centre for Virus Research (CVR) at the University of Glasgow in Scotland, the study found having the flu surprisingly reduces a person's chances of developing an infection with a common cold virus. This finding was valid at both the population level (or across the population as a whole) and the individual level (meaning within an individual person).

"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)," Dr. Pablo Murcia, study lead author and a senior lecturer at CVR, which is the United Kingdom's largest group of human and veterinary virologists, said.

Computer analysis of the data derived from the study revealed that when flu activity increased in the winter, infections with the cold rhinoviruses decreased. When researchers looked at individual patients, they found people infected with influenza A were 70 percent less likely to also be infected with rhinovirus, compared with patients infected with other types of viruses. Influenza A is the only flu virus that causes global flu pandemics.

"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," Sema Nickbakhsh, study first author and a research associate at CVR, said.

She said the research team believes respiratory viruses might be competing for resources in the respiratory tract during the cold winter months.

"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 added.

Nickbakhsh believes other factors might be responsible. One of these is the fact people stay at home when they are sick, which may reduce the chances of catching another virus. Researchers said more studies are needed to better understand the biological mechanisms underlying these virus-virus interactions.

But, if you must know, catching a cold when you already have the flu is a very rare occurrence. So it's either one or the other.

In this study, researchers analyzed information from more than 36,000 individuals in Scotland that provided more than 44,000 throat and nose swabs for testing for respiratory illnesses over a nine years 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 percent tested positive for at least one virus. Eight percent tested positive for co-infection with at least two viruses.

Flu
While flu antiviral drugs can help in some cases, they are not meant to act as a substitute for the flu vaccine. Zohre Nemati/Unsplash