The saying goes that an ounce of prevention is worth a pound of cure. As the coronavirus continues to spread across the globe, it’s worth noting that while there’s no cure or vaccine, there is a simple, effective form of prevention: stay home when you’re sick, or if you’ve been told you might be.

The CDC wants people to stay home when they are sick and self-isolate to prevent the spread of the virus, but because reports suggest that most cases of COVID-19 are mild for the majority of healthy people this seems extreme to some people. But to families with immunocompromised or medically fragile children (my own included), or with elderly parents or grandparents, they’re not extreme at all.

These vulnerable populations are depending on everyone else to take the coronavirus threat seriously. An otherwise healthy person who contracts coronavirus may recover just fine—but someone they inadvertently infect along the way may not be so lucky.

Parents and loved ones of those facing an elevated risk are pushing back against the idea that the virus is no big deal, and health officials are attempting to make the messaging clearer because one individual not abiding by self-quarantine recommendations can have a ripple effect on a community.

Recently a Missouri dad who says he didn’t understand that he was supposed to self-quarantine went to a school dance with one of his daughters while another daughter was awaiting her coronavirus test results. When the test came back positive this father left the dance—but two schools had to be closed, according to the Washington Post and now many families’ lives are disrupted. The CDC says it’s still learning how the virus spreads, and it’s possible that even those without active symptoms could pass it on to others—meaning that the father could have infected dozens of others, who in turn could have infected dozens of others as well.

As the number of coronavirus cases increases in the U.S., a growing number of them have been “community spread“—meaning the person who contracted the virus hadn’t traveled or knowingly been in contact with another infected person. In light of those cases, there have been more calls to practice social distancing—described by The Atlantic as staying away from public places, avoiding big gatherings, and avoiding non-essential travel.

You’ve probably seen plenty of people questioning why the coronavirus has incited such fear, or saying that it’s no more a threat the flu. But the facts don’t seem to back that up. The Director-General of the World Health Organization says coronavirus causes a more severe course of illness than the flu, and there’s no natural immunity to it since the COVID-19 strain is so new. But he says there is one key difference between the two: “We don’t even talk about containment for seasonal flu–it’s just not possible. But it is possible for COVID-19.”

The flu isn’t containable, but the CDC does ask (every year) for people to stay home when they have influenza. But people don’t (for many unfortunate reasons) and sick kids get sicker. Moms with compromised immune systems end up hospitalized and miss time with their families. Grandparents that families rely on for childcare can’t provide it, because they caught the flu from someone who couldn’t or wouldn’t stay home, and now they’re hospitalized. Maybe COVID-19 will change how seriously we consider the risk to others that we take when we go out with a virus. Parents on social media are hoping it does.

Containing coronavirus—and by extension, protecting the immunocompromised, the elderly, and disabled—will take sacrifice. Missing a school dance, canceling a vacation, or rescheduling a big gathering can be incredibly disappointing—but when the upside is saving lives—it should be an easy call.