Twitter said Wednesday it would take renewed action to clamp down on misinformation on the site, requiring people to remove tweets that deny health recommendations or promote ineffective or misleading health claims. The change comes amid the ongoing spread of COVID-19, or the novel coronavirus, that has infected more than 200,000 people.

“As the entire world faces an unprecedented public health emergency, we want to be open about the challenges we are facing and the contingency measures we’re putting in place to serve the public conversation at this critical time,” the company wrote in an updated safety policy.

Starting this week, the social media giant will broaden its definition of harmful content, which is banned on the site, to include denials of global or local health recommendations, established science about transmission, manipulation of the pandemic for the gain of a third party or material meant to incite action or cause widespread panic, among many other measures. Twitter will also work to combat racism and xenophobia, saying claims such as “avoid businesses owned by Chinese people” would be against its rules.

The company also urged users to visit its coronavirus “events” page to see up-to-date information about the ongoing pandemic.

The change is a new effort to squash misinformation about the coronavirus outbreak that has already spread like wildfire across the internet. Earlier this week Facebook drew fire after briefly marking stories with information about the coronavirus as spam.

Facebook unveiled its own portal for coronavirus information on Wednesday, with Chief Executive Mark Zuckerberg saying it would give people access to “good information and trusted sources during the pandemic.”

It’s unclear how effective Twitter’s policies will be as they would apply to many messages already being shared around the site. The company said it would use machine learning and a “global content severity triage system” to prioritize rule violations that “present the biggest risk of harm.”

“As we’ve said on many occasions, our approach to protecting the public conversation is never static. That’s particularly relevant in these unprecedented times,” the company said. “We intend to review our thinking daily and will ensure we’re sharing updates here on any new clarifications to our rules or major changes to how we’re enforcing them.”