Twitter has a word of caution for brands in the time of coronavirus: “This is not a ‘marketing opportunity.’”

On Wednesday, Twitter posted a blog outlining the potential dangers for brands trying to communicate online while the world faces a COVID-19 pandemic. Twitter did not tell brands to avoid discussing coronavirus, that would be near impossible, but they just have to be thoughtful about the message.

“Let’s be clear,” said Alex Josephson, global head of Twitter Next, and Eimear Lambe, director of Twitter Next, in the blog post. “This is not a ‘marketing opportunity’ to capitalize on, and we do not recommend brands opportunistically linking themselves to a health scare.”

Brands are looking for any guidance they can get on how to respond to the outbreak. Twitter said that someone tweets about coronavirus every 45 milliseconds. “What we are facing is unprecedented,” Josephson and Lambe said. “This is global, this is open-ended, and this could affect every brand, every business, and every individual. In times of crisis, people look to leaders and institutions for guidance, reassurance and information. Increasingly, they also look to brands.”

Many advertisers have adjusted their messaging during the COVID-19 outbreak. Hershey just had to pull ads that showed people hugging and touching, because it was seen as potentially insensitive to promote close contact while most people are practicing “social distancing.” Coors Light pulled the plug on a campaign for March Madness with the slogan: “Official beer of ‘working’ remotely.” That, too, could have come off as tone deaf while more people are working at home, not to watch college basketball, but to avoid the contracting the disease.

The mood of the nation has changed as multiple states have had to declare emergencies while more cases of coronavirus emerge. The illness is considered more dangerous than most common flu strains, and U.S. officials and businesses are taking extraordinary measures to help slow the spread.

All the digital platforms have dealt with the surge in coronavirus conversation—and misinformation—and they have taken steps to promote authoritative voices. On Wednesday, YouTube CEO Susan Wojcicki said the company was donating ad space to official health agencies to promote useful information: “We're using our homepage to direct users to the World Health Organization, the Centers for Disease Control and Prevention,” Wojcicki said, “and other local authoritative organizations around the world to ensure users can easily find updates. We're also donating advertising inventory to governments and NGOs in impacted regions, who are using it to spotlight timely, helpful information.”

In many cases, brands too have to step up as responsible voices. Companies in the travel industry, for instance, need to update consumers about the status of flights, cruises and hotels. Retailers need to inform the public about buying high-demand products. Home-cleaning brands need to communicate about the effectiveness of their products in a health crisis.

The Twitter execs shared examples of brands with appropriate tweets during the crisis. The examples included tweets from Google and Slack regarding working from home. Studios behind the new James Bond movie “No Time to Die” tweeted about delaying its release. Airlines like British Airways, JetBlue and Southwest Airlines have tweeted about flight flexibility for disrupted travelers.

“This is not about looking at what others are doing and copying,” Josephson and Lambe said. “It’s about understanding the unique role your brand plays in people’s lives, how that has changed, and how your brand can help or be useful during this crisis. It’s also about looking for opportunities to lead by example, and do the right thing, where it makes sense for your business.”