Hillary Clinton has pneumonia. At least that’s what her doctor says, after she looked unsteady on her feet at a 9/11 ceremony on Sunday. Now, political spectators are calling for Clinton to release more detailed medical records, and many people—yes, those many people—are speculating about how she’s doing. Everyone: She’s probably going to be fine.

Pneumonia is an infection, specifically of the tiny sacs called alveoli—they look like bunches of grapes—that transfer oxygen from the air you breathe to the blood you ... have. Someone who has the infection, viral or bacterial, coughs up droplets. You inhale them, and the microbes get into your lungs. If you're not already immune to that particular pathogen, your alveoli start producing fluid, and you start coughing, get a fever, and feel like crap. It's common (4 million cases a year), and not that serious. And it’s four times as common in people over 65. Clinton is 68.

Physicians and researchers we talked to said Clinton probably has community-acquired pneumonia, the most common kind (as opposed to what you catch in hospitals or nursing homes, which are more virulent). “You get it from being out in the world,” says Catherine Forest, a clinical professor at Stanford Medicine. You’re more likely to get it if you’re not getting enough sleep. Or because of heat, or physical exertion, or stress. Or being on airplanes a lot, since that means being in closer proximity to people who might already be infected.

In other words? Campaigning for president is a very good way to get pneumonia. “Clinton’s in crowds all the time,” says Michael Niederman, a lung doctor at Cornell Medicine. “I’m sure someone’s coughed in her face before.” And Clinton has a brutal schedule. Last week, she flew to Illinois and Ohio on Monday to meet with labor unions, stopped in Florida on Tuesday for a rally, then headed to New York on Wednesday, North Carolina on Thursday, and back to New York on Friday. Listen, you'd get sick, too.

If you’re a Clinton supporter, the bummer about this diagnosis is that it plays into the conspiracy narratives her opponents have been spinning about her overall health and, by extension, fitness to be president. It’s *especially *a bummer because catching pneumonia has nothing to do with physical ability to assume the presidency. “It’s really more of a political issue than a health issue,” says Art Reingold, an epidemiologist at UC Berkeley. Most people recover fully in a few weeks.

It is somewhat telling that doctors didn’t send Clinton to the hospital, Forest says. That means Clinton didn’t have very low blood pressure, a high breathing rate, or an altered mental state. Standard course of treatment is antibiotics, at home. “If she looked so much better so quickly, they probably just treated her fever and gave her some fluids,” Niederman says.

So: It’s probably nothing to get worked up over. Everyone gets sick on the campaign trail.