Two years ago, in a response to false information on social-media platforms, the United Nations special rapporteur on the promotion and protection of the right to freedom of opinion and expression condemned governments that disallow free speech in the name of public order. The report of the special rapporteur gave as an example the Chinese Cybersecurity Law of 2016, which “reinforces vague prohibitions against the spread of ‘false’ information that disrupts ‘social or economic order’, national unity or national security.”

As the world faces the COVID-19 pandemic, we are seeing what problems this suppression can wreak. What if the information deemed by government authorities as disrupting social order is not ‘false’, but instead a life-saving clue? When governments or their leaders repress information in hope of calming anxious publics, or deliberately release supposedly reassuring misinformation, they risk undermining their own credibility and their abilities to help people to counter real health threats.

Examples of this span the world. US President Donald Trump claimed that there would be a diagnostic test for “anybody that needs a test”, and that the malaria drug chloroquine could successfully treat COVID-19, although trials for its efficacy against the virus were not yet complete. One individual has since died after dosing himself with a form of chloroquine sold to clean fish tanks.

Iran, once known for its strong health-care system, has been hit hard by COVID-19. Iranians were already angry and mistrustful following their government’s accidental shooting down of a passenger aircraft in January, amid other grievances. In this climate of distrust, new anger emerged as the public felt that the government was not doing enough to slow the outbreak. The foreign minister, Mohammad Javad Zarif, tried to divert this anger by blaming the United States. Although US sanctions have taken a toll on daily life in Iran, and perhaps weakened their capacity in the COVID-19 response, the government also made conscious attempts to repress information about the state of the outbreak. Medical staff in Iran have been warned by authorities not to share any information about infected patients or limited resources, undermining the ability to respond.

The Canadian Broadcasting Corporation reported on 18 March that physicians in Russia fear there could be “hundreds” of deaths, despite Russian President Vladimir Putin’s assurances that all is under control. Some physicians say they are holding back from reporting suspected cases to health authorities as they are concerned about the state of the quarantine facilities where their patients would be sent, and fear that their own practices would be shut down. And news agency Reuters reported that the White House had kept important COVID-19 meetings classified — even though that meant keeping information from experts who would normally be consulted — while the President trumpeted ‘all under control’, until reality forced a rapid about-face.

Where official information sources are perceived as untrustworthy, the climate is set for the viral spread of unfounded speculation. COVID-19 has triggered a fountain of rumours — an indistinguishable mix of unverified information, helpful information, misinformation and intentionally manipulated disinformation. Between 1 January and mid-March 2020, our social-media monitoring at The Vaccine Confidence Project had captured more than 240 million digital and social-media messages globally referring to the new virus, with an average of 3.08 million messages per day. On Twitter, there have been 113 million unique authors sharing everything from messages from news reports and commentary on COVID-19, to views on quarantining measures, speculation on the source of the virus and home-brewed cures. These ranged from the relatively harmless — eat garlic — to the downright dangerous — drink bleach. One message falsely claiming to be from Stanford University in California recommended sipping water to kill the virus, or holding your breath for ten seconds to determine whether you are infected. (Neither works.)

As scientists rushed to investigate the new virus, conspiracy theories started to circulate about whether it was a naturally evolved new pathogen, one that inadvertently slipped out of a high-security laboratory in Wuhan or one that was deliberately created for biowarfare — an idea deemed plausible by some in the current context of geopolitics and deepening tensions between the United States and China.

On 19 February, a group of scientists issued a statement in The Lancet to quell the tsunami of conspiracy theories. They confirmed that investigations “overwhelmingly conclude that this coronavirus originated in wildlife”. But between the identification of the new virus and the confirmation of its origin, there was no evidence available to counter the rumours that went viral, and — for those who want to put stock in them — they persist.

The challenge for policymakers and health authorities is that, although some information is clearly false, and even harmful, the validity of other posts is less clear-cut. Some are merely stirring up doubts, confusion and conspiracy, and undermining trust in health authorities, but are difficult to pin down and refute. Some emerging, albeit unverified, information might be valuable, and deleting it would cause harm.

The epidemic began with a poignant example of potential life-saving information suppressed as a rumour. On 30 December, Li Wenliang, a young ophthalmologist in Wuhan, China, posted a message to colleagues that tried to call attention to a severe acute respiratory syndrome (SARS)-like illness that was brewing in his hospital. The Chinese government abruptly deleted the post, accusing Li of rumour-mongering. On 7 February, he died of COVID-19.

This is a complicated landscape that is not just a matter of debunking a piece of misinformation. This is about relationships between publics and politicians, a lack of trust in the motives of governing powers and fears among leaders that the truth would spark public disorder and dissent. Advice to “Keep calm and carry on” can have exactly the opposite effect in the context of a fatal, and evolving, new virus.