COVID-19 could be an especially serious threat to people who smoke tobacco or marijuana or who vape because the virus attacks the lungs, according to the National Institute on Drug Abuse (NIDA).

In a blog post this week, NIDA Director Dr. Nora Volkow wrote that people with opioid use disorder and methamphetamine use disorder also may be vulnerable due to those drugs’ effects on breathing and the lungs.

The Centers for Disease Control and Prevention reported young adults under age 44 make up a substantial portion of coronavirus hospitalizations in the United States.

Stanton Glantz, Director of the Center for Tobacco Research Control & Education at the University of California, San Francisco, said vaping may help explain some cases in this younger age group. “Vaping affects your lungs at every level. It affects the immune function in your nasal cavity by affecting cilia which push foreign things out…[T]he ability of your upper airways to clear viruses is compromised,” Glantz told CNN.