The bacteria that lives inside your nose could determine how severe your cold symptoms are.

For example, people whose noses are rich in Staphylococcus bacteria had more severe nasal symptoms than cold sufferers who have less staph, new research shows. That’s despite their colds being caused by the exact same strain of virus.

The researchers found that the bacteria in volunteers’ noses fell into six different patterns of nasal microbiomes. The different patterns were associated with differences in symptom severity. The compositions also were found to correlate with viral load — the amount of cold virus inside the body.

The discovery surprised even the longtime cold researchers who made it. “The first surprise was that you can kind of identify these different buckets that people kind of fit into, and then the fact that the buckets seem to have some impact on how you respond to the virus and how sick you get was also interesting,” said Ronald B. Turner, MD, of the University of Virginia School of Medicine. “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.”