For people suffering from a cold, the severity of their symptoms may be linked to the mix of bacteria that inhabit their nose. New research suggests the amount and type of organisms residing in the nose might explain why some people’s symptoms are worse than others – even if they are infected with the same strain of virus.

For the study, researchers analysed the nasal bacteria of 152 people before and after they were infected with the same cold virus. People whose noses have a lot of Staphylococcus bacteria had more severe nasal symptoms than those with less of this type of bacteria.

“There were effects on virus load and how much virus you shed in your nasal secretions. So the background microbiome, the background bacterial pattern in your nose, had influences on the way that you reacted to the virus and how sick you got,” said researcher Dr Ronald Turner, who’s with the University of Virginia School of Medicine. The findings were published recently in the journal Scientific Reports.

“What we’re reporting is an association, so it’s entirely possible that the fact that you have staph in your nose and you have more symptoms is not directly related,” Turner explained in a university news release. “It may well be that there’s some underlying host characteristic that makes you likely to have staph in your nose and also makes you more likely to become ill.” The researchers noted that the composition of nasal bacteria and the severity of people’s symptoms could boil down to genetics.