Danish doctor accurately quoted on masks and Covid-19, but graphic misleading

A graphic widely shared on Facebook in South Africa in August 2020 draws links between wearing masks and deaths from Covid-19 in the small Scandinavian country of Denmark.

“Denmark – no masks”, its header reads. It then gives the number of deaths in Denmark during the “2018 Flu season” as 2,103 and from Covid-19, by 8 August 2020, as the much lower 617. 

The graphic shows a photo of a man in doctor’s scrubs. He is identified as “Dr Henning Bundgaard, chief physician at Denmark’s Rigshospitalet”. 

“No one has any documentation that face masks outside hospitals work at all,” it quotes Bundgaard as saying. “And I think it is rational to provide this documentation before we demand that people need to wear masks out in the open. All these countries recommending face masks haven’t made their decisions based on new studies.”

Text on the photo reads “Fearless Ontario”, the name of a Canadian Facebook page that has posted a similar graphic making the same claims. 

Facebook has flagged the graphic as potentially false. But did a Danish doctor make these statements? Are the figures correct for Denmark? And is there no documentation that masks worn in public help prevent Covid-19?

Doctor accurately quoted

Dr Henning Bundgaard does work at Rigshospitalet, a research and teaching hospital in Copenhagen, Denmark’s capital. 

The graphic suggests he is the most senior doctor at the hospital, but Bundgaard is not listed as a “chief physician” on the hospital‘s website. The institution has several “chief physicians” who head different departments.

Instead, Bundgaard is a professor and chief consultant of cardiology in the hospital’s department of cardiology and at the University of Copenhagen.

But the quotes attributed to him are accurate.

On 11 May Bundgaard was interviewed by the Local, an English-language Danish news site. “No one has any documentation that face masks outside hospitals work at all,” he said. “And I think it is rational to provide this documentation before we demand that people need to wear masks out in the open.”

In an interview with US news organisation Bloomberg, published on 26 July, he said: “All these countries recommending face masks haven’t made their decisions based on new studies.”

Bundgaard is the lead investigator in the clinical trial Reduction in Covid-19 Infection Using Surgical Facial Masks Outside the Healthcare System. The trial had 6,000 participants and took place from 2 April to 2 June. But by 15 September no results had been posted. 

Masks not compulsory in public in Denmark

The doctor’s most recent remarks came after Berlingske, a leading Danish newspaper, questioned why authorities weren’t stricter about implementing mask wearing. They compared this to the people in many parts of the world and “even Donald Trump”, US president, wearing masks to help stop the spread of Covid-19. 

Denmark’s less strict approach has been reported by the international media. It was only made compulsory to wear a mask on public transport from 22 August, many months after more stringent rules were put in place in other countries.

By mid-September, the country was experiencing an increase or “second wave” of Covid-19 cases. Authorities were considering stricter regulations, including making masks compulsory in supermarkets and restaurants and clamping down on nightlife in cities.

Figures partial, misleading

By 8 August, 620 people in Denmark had died from Covid-19. This is close to the figure in the Facebook graphic.

The graphic claims 2,103 people died in the “2018 Flu season”. This is less accurate.

According to Statistics Denmark, 2,103 people died in 2018 from both pneumonia and influenza. And this is for the whole of 2018, not just the “flu season”.

A report on the 2018/19 flu season from Statens Serum Institut (SSI), a research institute responsible for Denmark’s preparedness against infectious diseases, is more specific.

It estimates that “the total estimated excess mortality related to influenza for the entire 2018/19 season was 790 deaths”. The season was from early October 2018 to mid-May 2019.

But what is “excess mortality”? It is “observed mortality minus expected mortality” and “estimated using statistical models that are based on historical data”, according to the SSI.

And does the count of Covid-19 deaths measure excess mortality? This is not at all clear, and certainly not clear in the graphic. 

Compare apples to apples

Knowing the total number of deaths from a disease without looking at the prevalence – the number of cases – of the disease in the total population is not particularly meaningful. 

As Peter Beech wrote for the World Economic Forum in the early days of the pandemic: “In just a few short weeks, we’ve all made the collective journey from pandemic ignoramuses to budding armchair virologists.”

In July 2020, Andrew Wilson and Jonathan Niles-Weed, assistant professors at New York University’s Center for Data Science and the Courant Institute of Mathematical Sciences, outlined five things to keep in mind when evaluating data about Covid-19. 

Their last point was to consider “what information is missing”. Wilson said: “Many claims are factually correct but misleading due to crucial missing information.”

Masks work outside hospitals

The graphic’s overall message is that masks don’t help prevent the spread of Covid-19. This is dangerous misinformation.

Face masks have become a political issue in some countries, particularly the USA but also in Canada. Arguments against wearing masks are often not based on existing science.

There is plenty of documentation that masks work outside hospitals.

A study published in Health Affairs, for example, found that the rise in Covid-19 cases slowed after masks were made compulsory in 15 US states and the District of Columbia.

And a study published in June looked at Covid-19 deaths in 198 countries and found that those with cultural norms or government policies favouring mask-wearing had lower death rates.

The quotes from a Danish doctor and the figures comparing deaths from Covid-19 to deaths from flu two years earlier may be largely correct. But these facts provide little insight into the deadliness of Covid-19 compared to flu or the effectiveness of measures to stop the disease in Denmark.

And it is not correct, as Bundgaard said in May, that “no one has any documentation that face masks outside hospitals work at all”.