Last year we had a call from a concerned but grateful parent. Having previously been sceptical about vaccines, having read one of our fact checks, she’d decided to go ahead and have her children vaccinated. It sticks in my mind as an example of the harm that bad information can do – not just to our democracy, which as fact checkers we’re often asked about – but to our health.

Misleading claims around vaccines have encouraged parents to disregard medical advice and take unnecessary risks with their children’s lives. Since the outbreak of the new coronavirus began, we have been fighting a similar tide of false claims and exaggerations. Much of this has originated and spread on social media. As is common during global news events – especially health crises – some have sought to pin the blame on familiar enemies, whether it is 5G technology, the Rothschilds or Chinese lab scientists. Many people have spread conspiracy theories, playing on our fears by suggesting that somehow the institutions that are supposed to protect us somehow had forewarning of – or even planned – the global outbreak of this deadly virus.

But of particular concern in the short term are those spreading false or misleading health advice. This is often done with the best of intentions: it’s a natural response to a scary situation to pass on advice that you think might help protect your friends and family. But if that information turns out to be inaccurate, you risk doing more harm than good.

The misinformation we’ve seen broadly falls into three separate categories. Some, such as the claim that children are immune, begin life with a kernel of truth – here, that the symptoms in children are generally less severe than they are in older people. But without the proper context and caveats, these morph over time into something more dangerous. Children may suffer less from the virus, but they could still pass it on to more vulnerable friends and family.

Others revolve around misconceptions of the term “coronavirus” itself. Without the crucial context that coronaviruses are a large family of viruses that we’ve known about since the 1960s, perfectly normal references to coronaviruses that predate this outbreak can suddenly seem like evidence of a conspiracy. And so we end up with people believing that vaccine trials for previously existing coronaviruses show the outbreak was manufactured, or even that the makers of Dettol somehow knew about the outbreak in advance, because they list “human coronavirus” on their bottles.

The third type is bad information masquerading as official health guidelines and advice. This week, the Department for Culture, Media and Sport (DCMS) and the NHS both announced measures designed to combat bad information around this coronavirus. DCMS has formed a cross-departmental taskforce to monitor misleading claims, while the NHS has teamed up with tech giants such as Twitter and Facebook to signpost official advice on their platforms. While these announcements are welcome, it is just as important to challenge bad information as it is to direct people to reliable advice.

A Facebook post shared more than 300,000 times made several dangerous claims. Chief among them was the “advice” that a runny nose means you have a common cold – not Covid-19. This is wrong; this symptom is rarer in Covid-19 sufferers, but it does not rule it out. The post also made the unfounded claim that the virus will die in temperatures above 27C (80F). The potential real-world repercussions of such a post (which has now been amended after we approached the author) are plain to see. It’s right that social media platforms have come under scrutiny. But we’ve also seen misleading claims emerge from traditional print and broadcast media.

Telling people that the new coronavirus “doesn’t infect children” – as one broadsheet columnist claimed on Twitter – may lead people to make potentially fatal decisions. Journalists have also reported several false claims and conspiracy theories on the new coronavirus. At various times, readers of the Daily Express have been told that an academic paper claimed the virus has been “genetically engineered” to pass between humans more efficiently and that the World Health Organization knew about Covid-19 years before the current outbreak. Both claims are untrue. And multiple newspapers reported a false claim that mass cremations may be secretly taking place in Wuhan, based on “satellite images” that a bit of checking revealed weren’t satellite images at all.

As much as we rely on our public institutions and elected politicians, established news outlets are also seen as a dependable source of health information. While plenty of media outlets have been behaving responsibly, we deserve better than the exaggeration and speculation we’ve seen from some.

This is too important for a “publish first, check later” approach. The good news is that we all, journalists and citizens alike, can take steps to slow the spread of misleading claims. By taking time to think before you share – about where a claim has come from, how you might check its contents, and how it makes you feel – we’re less likely to inadvertently pass on bad information that puts our friends and family at an even greater risk.

We face a global public health crisis in the age of unprecedented and rampant misinformation – good health advice can make the difference between life and death.

• Tom Phillips is the editor of Full Fact