Credit: Getty Images/iStockphoto/wildpixel

This month, as the coronavirus spread across the U.S., many scientists and medical professionals decided to do the opposite: They stayed home. The American Physical Society canceled its March meeting, the American Chemical Society axed its spring conference, and several major health care meetings were scrapped. As of last Friday, I'd yet to hear anything about one meeting I'd signed up for long ago, a bioethics conference scheduled for this week in Boston.

So as I waited, I reached out to the bioethicists scheduled to attend and asked what they thought: Is it ethical to hold a conference during an epidemic? In Boston, there was particular concern because a cluster of cases had spread at a Biogen conference in the city at the end of February. The ethicists all agreed: Canceling big gatherings is the right thing to do. And by late afternoon, I'd gotten a notice that the meeting had been postponed to June of 2021.

When it comes to Covid-19 - the illness caused by the novel coronavirus - most of us could do with less fear and more guilt. According to the World Health Organization, most people infected with the coronavirus will survive. But as any bioethicist can tell you, even if you aren't at high risk of dying from the disease, you are at risk of spreading it and causing others to die. That may be true even if you feel perfectly healthy.

To start with, the coronavirus is much deadlier for some people than others. Data from China suggests the danger is greater for people with lung and heart disease, diabetes, hepatitis B, and cancer. And the older you are, the higher your risk. In China, the fatality rate for people over 80 was at least 14.8% - more than six times that of the population at large. Other estimates are closer to 20%, suggesting that for every five seniors with Covid-19, one will die from it. Younger people, who are far more likely to survive, have a responsibility to keep the virus from reaching their elders.

What's more, a measure of contagiousness epidemiologists refer to as R0 - the average number of people to which each infected person spreads the virus - isn't a constant of nature, determined solely by the properties of the virus. It also depends on human behavior. "If you had a population of hermits, R0 would be zero," Yale University network scientist Nicholas Christakis told me. In China, he said, the state's drastic interventions have caused R0 to fall to less than one, and the number of new infections has leveled off. We in the U.S. can also slow the spread of the virus, but we'll need to rely more on voluntary efforts than mandatory ones. Efforts like, say, canceling big meetings.

It's also important to slow the disease's spread so the health-care system doesn't become overwhelmed. The number of people who will die depends on whether everyone who needs proper hospital care can get it. While things are looking better in China, the system in Italy is starting to come under strain. According to a March 10 story in Bloomberg News, some regions are devoting 80% of acute care beds to the exploding number of Covid-19 patients. One overworked doctor in Italy reportedly declared that "every ventilator [is] like gold."

Scientific results coming out this week suggest that individuals might help prevent the same situation from recurring elsewhere. Researchers in Germany have released preliminary evidence that people are spreading this virus before they have any symptoms. And researchers at Johns Hopkins University published data suggesting this silent incubation period lasts five days on average - and far longer for some people. About one in 50 people with Covid-19 won't show symptoms for more than 11 days. That means washing your hands won't just protect you - it can protect others from you, even if you feel fine.

It's worth noting, too, that transmission can vary widely from person to person. This was striking during the 2003 SARS epidemic, which was also caused by a novel coronavirus. As described in the book "Spillover: Animal Infections and the Next Human Pandemic" by David Quammen, one doctor exposed through an early hospital outbreak in China got sick but then felt better, and decided to go to Hong Kong for a wedding. He ended up infecting 17 people at his hotel - including one who brought the disease to North America. That person's infection spread to several hundred people in Toronto, 36 of whom died. Little decisions can have big consequences.

The tragedy in the U.S. is that most people want to do the right thing but don't know how. The news is full of horror stories: someone with symptoms and possible exposure making multiple emergency-room visits just to get a test, and others quarantined but not given coherent instructions on how to interact with others in the household. A popular Facebook meme mixes good advice about hand hygiene with bad advice to hoard surgical masks. (Needless to say, do not hoard masks.)

As medical ethicist Art Caplan wrote this week, the government has failed to offer clear-cut information to a worried public. People under quarantine, especially, lack instructions on such basics as whether they can take out the trash and walk their dogs. "What about roommates if you've still got to share a bedroom and a bathroom?" he writes. "Can your partner still go to the store for you, let in workmen, accept deliveries? Few seem to know what to do if they are advised or ordered to stay home."

Several of the bioethicists scheduled to speak at the Boston meeting convinced me that we should focus advice less on protecting ourselves than on protecting others. There was a general sense of relief that the Boston meeting was canceled. Fortunately, the bioethics community isn't alone: In recent days Harvard and other universities moved classes online, and major events such as the South By Southwest festival have been canceled.

So you have a big event coming up, here's some friendly advice: If you're an organizer, consider postponing it. And if you're an attendee, consider staying home.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners. Faye Flam is a Bloomberg Opinion columnist. She has written for the Economist, the New York Times, the Washington Post, Psychology Today, Science and other publications. She has a degree in geophysics from the California Institute of Technology.