Twitter will remove tweets that run the risk of causing harm by spreading dangerous misinformation about Covid-19, the company has said, after weeks of criticism that its policies on misinformation were too lax.

Now, the social network says, it will be applying a new broader definition of harm to address content that “goes directly against guidance from authoritative sources of global and local public health information”.

According to Matt Derella and Vijaya Gadde, the heads of customer and legal, policy and trust and safety respectively, that means a whole range of content will now be removed that was previously allowed under the site’s rules, including:

Denial of health authority recommendations “with the intent to influence people into acting against recommended guidance”, like encouraging people not to socially distance themselves.

Description of treatments that are not immediately harmful but are known to be ineffective, even if made in jest, “such as ‘coronavirus is not heat-resistant - walking outside is enough to disinfect you” or “use aromatherapy and essential oils to prevent Covid-19.”

Description of harmful treatments such as “drinking bleach will cure Covid-19”.

Specific and unverified claims that incite people to action and cause widespread panic, such as: “The National Guard just announced that no more shipments of food will be arriving for 2 months - run to the grocery store ASAP and buy everything!”

Claims that specific groups or nationalities are never susceptible, or are more susceptible, to Covid-19.

False or misleading claims on how to differentiate between Covid-19 and a different disease, and if that information attempts to definitively diagnose someone, such as “if you have a wet cough, it’s not coronavirus - but a dry cough is” or “you’ll feel like you’re drowning in snot if you have coronavirus - it’s not a normal runny nose”.

Unlike Facebook, which encourages users to actively report misinformation, Twitter doesn’t offer that as option for user flagging. Users can still report such misinformation, however, and a spokesperson told the Guardian that “if an account holder sees information on the service that is directly against guidance from authoritative sources of global and local public health information - report it to us and we will assess under our new expanded rule. Reports made under any of [the existing] categories will be assessed under the updated rule – regardless.”

Additionally, Gadde and Derella say, the company will be enforcing the new rules “in close coordination with trusted partners, including public health authorities and governments, and continue to use and consult with information from those sources when reviewing content.”

Twitter has long been loth to introduce policies against misinformation, historically describing itself as the “free speech wing of the free speech party”. The company has no policies for flagging or removing false tweets, and in an update to its guidelines two weeks ago, only added extra rules to halt any attempt by advertisers to “opportunistically use the Covid-19 outbreak to target inappropriate ads”.

Instead, until now, the company has focused on providing accurate information to counter misinformation, partnering with the NHS to direct users to legitimate sources when they search for information.

Twitter’s decision to classify Covid-19 misinformation as harmful mirrors that of Facebook, which has long applied policies against “harmful misinformation” to justify removing content that advises against vaccination. Speaking on Wednesday night, the Facebook co-founder Mark Zuckerberg said: “Even in the most free expression-friendly jurisdictions like the US, you’ve long had the precedent that you don’t let people yell ‘fire’ in a crowded room, and I think that’s similar to people spreading dangerous misinformation in a situation like this.”