People who smoke are one of the priority groups for COVID-19 vaccination, USA Today reports. Evidence is mounting that people who smoke are at increased risk for poor COVID-19 outcomes, health experts say.

“I could see why people would feel as if that would be unfair, but people who are smokers are in general at higher risk for getting sicker when they develop COVID-19,” Dr. Samuel Kim, a thoracic surgeon at Northwestern Medicine in Chicago, told the newspaper.

A recent study in JAMA Internal Medicine found people who are current or former smokers are at higher risk of being hospitalized for or dying from COVID-19 than people who have never smoked.

Study co-author Dr. Joe Zein noted that smokers are more likely to have other diseases, such as high blood pressure, heart disease or chronic obstructive pulmonary disease, which further increases their risk of bad outcomes for COVID-19. He said smoking induces structural changes in the respiratory tract and compromises the body’s ability to fight infection.