SAN FRANCISCO (AP) — Facebook said Wednesday that it is banning ads that make false claims about products tied to the new coronavirus.

The social network said it is removing ads that feature a product and imply a limited supply, seeking create a “sense of urgency” in their mention of coronavirus. Ads that guarantee a cure or prevention are also banned, it said.

For instance, ads for face masks that claim the products are 100% guaranteed to prevent the spread of the virus are not allowed, the company said.

The ban went into effect this week. Facebook had previously banned ads, along with regular unpaid posts, that peddle fake cures such as drinking bleach, spread conspiracy theories about the virus, or discourage people from seeking medical treatment.

The ban went into effect as the World Health Organization reported that the number of new cases outside China exceeded the number of new infections inside the country for the first time on Tuesday. The COVID-19 virus has now spread to at least 39 countries.