“I am not wearing this mask,” said the 35-year-old man sitting in front of us, gasping for breath while ripping off the ear loops. “COVID is a hoax,” he declared as the monitor showed his oxygen level was dropping quickly.

Nearly every emergency medicine provider in the U.S. has similar stories of the extraordinary living proof of dishonesty’s lethal toll. Those who eschew the clear science and public health research about vaccines, masks and social distancing visit the cost of this lie on their loved ones and neighbors, on their friends and on strangers unfortunate enough to cross their path.

Political leaders who blithely pay lip service to the conspiracies that fuel this ignorance may not see the consequences of their words, but we do. We’ve seen organs shutting down as the disease takes its deadly toll. We’ve seen patients say their goodbyes over video screens.

Now, with vaccines here and summer on the way, case counts are dropping and so is the death toll. But we know this pandemic isn’t over yet, especially in the many countries that do not have America’s ready access to COVID-19 vaccines. We know that as long as the virus circulates, it can mutate and take off again once chilly weather forces us all back indoors. We know this is a real and legitimate fear until the vast majority of people overcome the web of myths on their social networks and get vaccinated.

It’s true that vaccines are not 100% effective. Some people cannot mount a full immune response due to underlying health conditions. “Breakthrough” infections, too — testing positive for the virus after being fully vaccinated — may also occur. As of April 30, the latest CDC data showed 10,262 breakthrough infections out of 101 million vaccinated with only 10% (995) of those infected requiring hospitalization. But do not be fooled — the CDC states that fully vaccinated individuals 65 and older are 94% less likely to be hospitalized with COVID-19 than are unvaccinated peers.

It’s encouraging that social media companies and some conservative leaders have begun to take seriously the ramifications of the political conspiracies they helped to spread. Now, they must do the same for rampant and lethal disinformation.

Sadly, this leads to real harm: One study of Fox News viewers found that whether they watched a show on the network that took COVID-19 seriously or one that dismissed it, led to significant behavior change, which was associated, in turn, with higher levels of COVID-19 cases and deaths. Your words matter, so act like it. Tell the public that COVID-19 is dangerous, and that those not yet vaccinated should continue to wear masks and practice social distancing. It is not enough to post a photo receiving a vaccine or wearing a mask, though you should do those things too. You should also use the megaphone afforded by your position to debunk the lies that put people at risk.

With almost seven in 10 Americans using social media, companies like Twitter and Facebook have an outsized impact on the quality of our national discourse. And as with countering QAnon conspiracies, they have a clear moral obligation to protect community safety and individual welfare from the COVID-19 infodemic. Platforms should aim to influence the behavior and decision-making of individuals by “nudging” users into reading more from verified organizations like the Centers for Disease Control and Prevention (CDC).

This is not to say there’s no room for debate over many aspects of COVID-19. After all, science is an endless process of discovery, and there is much we are still learning. But there are clear falsehoods — that masks don’t reduce spread, that people without symptoms can’t spread the virus, that vaccines cause COVID-19 or infertility or something else — whose dissemination leads directly to illness and death.

What can you do? Be honest with yourself: support investigative journalism, listen to public health experts, and remain skeptical of what you see on social media. Diversify the people and sources of opinion you choose to “follow,” similar to how physicians spend ample time researching treatment options before making life-and-death decisions. Remember that things can be true whether or not you believe in them.

As deliberate as you are with your news consumption, be doubly careful with what you share. That share button may seem innocuous, but it gives you tremendous power to shape others’ perceptions, and the behaviors that spell the difference between sickness and health.

There is nothing worse than seeing innocent lives fall victim to the lies willfully festered by others. We must fight fear with science. Sustain truth with facts. And work harder across fields to fight disinformation with innovation. If we fail, more oxygen will be sucked out of the lungs of many in the months to come.

Erik J. Blutinger and Clifford M. Marks are emergency physicians at Mount Sinai Health system in New York City.