As early as February, with the global pandemic spreading fast, the World Health Organization issued a warning about an "infodemic", a wave of fake news and misinformation about the deadly new disease on social media.

Now with hopes hanging on Covid-19 vaccines, the WHO and experts are warning those same phenomena may jeopardise roll-out of immunisation programmes meant to bring an end to the suffering.

"The coronavirus disease is the first pandemic in history in which technology and social media are being used on a massive scale to keep people safe, informed, productive and connected," the WHO said.

"At the same time, the technology we rely on to keep connected and informed is enabling and amplifying an infodemic that continues to undermine the global response and jeopardises measures to control the pandemic."

More than 1.4 million people have died since the pandemic emerged in China late last year, but three developers are already applying for approval for their vaccines to be used as early as December.

Beyond logistics, though, governments must also contend with scepticism over vaccines developed with record speed at a time when social media has been both a tool for information and falsehood about the virus.

The WHO defined an infodemic as an overabundance of information, both online and offline, including "deliberate attempts to disseminate wrong information". 

Last month, a study from Cornell University in the United States found that US President Donald Trump has been the world's biggest driver of Covid-19 misinformation during the pandemic. 

In April, Trump mused on the possibility of using disinfectants inside the body to cure the virus and also promoted unproven treatments. 

Since January, AFP has published more than 2,000 fact-checking articles dismantling false claims about the novel coronavirus. 

"Without the appropriate trust and correct information, diagnostic tests go unused, immunisation campaigns (or campaigns to promote effective vaccines) will not meet their targets, and the virus will continue to thrive," the WHO said. 

- 'Unparalleled scale' -
Three vaccine developers -- Pfizer/BioNTech, Moderna and AstraZeneca/Oxford University are leading the pack -- and some governments are already planning to start vaccinating their most vulnerable this year.

But with Facebook, Twitter, YouTube or WhatsApp acting as vectors for dubious facts and fake news, "disinformation has now reached an unapparelled scale," said Sylvain Delouvee, a researcher in Social Psychology at Rennes-2 University. 

Rory Smith of the anti-disinformation website, First Draft, agreed. 

"From an information perspective, (the coronavirus crisis) has not only underlined the sheer scale of misinformation worldwide, but also the negative impact misinformation can have on trust in vaccines, institutions and scientific findings more broadly," he said.

Rachel O'Brien, head of the WHO's immunisation department, said the agency was worried false information propagated by the so-called "anti-vaxxer" movement could dissuade people from immunising themselves against coronavirus. 

"We are very concerned about that and concerned that people get their info from credible sources, that they are aware that there is a lot information out there that is wrong, either intentionally wrong or unintentionally wrong," she told AFP. 

- Vaccine hesitancy -
Steven Wilson, a professor at Brandeis University and co-author of a study entitled "Social Media and Vaccine Hesitancy" published in the British Medical Journal last month, saw a link between online disinformation campaigns and a decline in vaccination. 

"My fear regarding the impact of disinformation on social media in the context of Covid-19 is that it will increase the number of individuals who are hesitant about getting a vaccine, even if their fears have no scientific basis," he said.

"Any vaccine is only as effective as our capacity to deploy it to a population." 

Among the more outlandish claims by conspiracy theorists, for example, is the idea that the novel coronavirus pandemic is a hoax or part of an elite plan, masterminded by the likes of Bill Gates, to control the population. 

And vaccination programmes, those groups say, are a shield for implanting microscopic chips in people to monitor them. 

Such notions can find fertile ground at a time when polls show that people in some countries, such as Sweden and France, are already sceptical about taking vaccines, especially when the treatments have been developed in record time with no long-term studies yet available on their efficacy and possible side-effects.

- Growing mistrust -
Last month, a poll by Ipsos suggested that only 54 percent of French people would immunise themselves against coronavirus, 10 percentage points lower than in the US, 22 points lower than in Canada and 33 points lower than in India. 

In 15 countries, 73 percent of people said they were willing to be vaccinated against Covid-19, four percentage points lower than in an earlier poll in August. 

But it is not just vaccines -- more and more people express a growing mistrust of institutions, experts say. 

"The common theme" among conspiracy theorists "is that our 'elites' are lying to us," said Rennes-2 University's Delouvee.

Disinformation is based on growing mistrust of all institutional authority, whether it be government or scientific.

"When people can't easily access reliable information around vaccines and when mistrust in actors and institutions related to vaccines is high, misinformation narratives rush in to fill the vacuum," the First Draft report said. © Agence France-Presse

Narcolepsy fiasco spurs Covid vaccine fears in Sweden
Take a vaccine developed in haste? Never again, says Meissa Chebbi, who, like hundreds of other young Swedes suffered debilitating narcolepsy after a mass vaccination campaign against the 2009-2010 swine flu pandemic.

The experience has shaken Swedes' confidence in any future vaccine against the new coronavirus, compounding fears about unknown long-term side effects.

"I will never recommend that," 21-year-old Chebbi told AFP when asked about taking a speedily developed vaccine. "Unless you really have to take it because of life-threatening circumstances." 

The Swedish case highlights the complex task governments face in rolling out vaccines against the coronavirus, especially at a time when rabid social media misinformation is feeding scepticism in state institutions and even about the disease itself. 

The trauma over vaccines is particularly notable in Sweden, which normally boasts participation of more than 90 percent in its voluntary children's vaccination programme.

But a recent survey conducted by the Novus polling institute suggested that 26 percent of Swedes do not plan to take any of the Covid-19 vaccines being developed and 28 percent are undecided.

Forty-six percent said they would get a jab. 

Of those opposed, 87 percent said it was due to fears over as-yet unknown side effects.

Health authorities in the Scandinavian country in 2009 urged the public to voluntarily take the Pandemrix vaccine against swine flu, made by British drug company GlaxoSmithKline.

More than 60 percent heeded the call -- the highest level in the world.

But Chebbi and hundreds of others, primarily children and young adults under 30, were later diagnosed with narcolepsy as a side effect of the vaccine.

A link was eventually established to an adjuvant, or booster, in the Pandemrix vaccine which was intended to strengthen the immune response.

Narcolepsy is a chronic disorder of the nervous system that causes excessive and often uncontrollable drowsiness.

"I have sleep attacks all the time in all kinds of situations and at inappropriate times... In my food, at job interviews, at lectures, seminars, at university. I've fallen asleep at my workplace, I fall asleep on buses and everywhere," Chebbi says.

"It has destroyed my life."

The Swedish Pharmaceutical Insurance has so far approved 440 of 702 narcolepsy claims linked to Pandemrix, paying out a total of 100 million kronor (9.8 million euros, $11.6 million) in compensation. 

- 'If only we had known' -
Anders Tegnell, Sweden's state epidemiologist and the face of the country's controversial 'softer' response to the new coronavirus, was among a group of experts at the Board of Health who called for the mass vaccination in 2009-2010.

"Of course the decision would have been completely different if we had known about the side effects. But they were completely unknown, they were a surprise to everybody," Tegnell told AFP in an interview.

"There has been an international consensus for many years that the best thing to do during a pandemic is to vaccinate, and that's really the only long-term solution we have."

Babis Stefanides, a 36-year-old Stockholm resident, said he's too wary to take a Covid jab.

"I'm not planning to take the vaccine," he told AFP. "There are just too many questions."

Tegnell said he understood Swedes' concerns.

"Of course when you have a new vaccine that we don't know very much about yet -- against a disease that we don't know very much about -- everybody ... wants to have more information before they make a decision on this," he said.

"We are going to inform about these vaccines when we know a little bit more about them."

Tegnell ruled out making any future vaccine mandatory.

According to the director of the Swedish Public Health Agency, Johan Carlson, 60 to 70 percent of the population would have to be vaccinated in order to stop the spread of the virus.

"Everyone needs to have a think and decide what to do. Usually in Sweden, most people end up getting vaccinated," Carlson told Swedish Television on Sunday.

In a bid to assuage fears, Sweden plans to set up a register to quickly detect any side effects from a future Covid vaccine.

- Solidarity in question -
Hannah Laine, a 37-year-old social worker in Stockholm, said she, her husband and their three kids would definitely be getting the vaccine -- despite her fears.

"If it's approved for the market and we notice that the public health agency and society is saying that we should take the vaccine, we'll do it," she told AFP.

"We have to take our moral responsibility for the elderly and the sick. We'll take it, maybe not for our sake but for society's."

That kind of thinking worries Elisabeth Widell, chairperson of the Narcolepsy Association.

She says health authorities were not wrong to call for a mass vaccination in 2009, but they appealed too heavily to Swedes' sense of solidarity and she hopes they won't do that again.

"People who choose not to get vaccinated should not be blamed and shamed. Because it's not mandatory, which means it's a free choice."

She urged Swedes to "do your own risk and benefit analysis".

Narcolepsy sufferer Chebbi remains determined.

"I'm not going to take the (Covid) vaccine until after about five years when we know what the risks are."