by Freddie Sayers
Friday, 20
November 2020
Video
11:53

Danish mask study author: effect may be small, but worthwhile

by Freddie Sayers

The Danish ‘randomised control trial’ study into the protective effects of facemasks caused the predictable furore when it was published this week. Comparing a sample of 3,000 people who were wearing masks and 3,000 people who were not, 42 of the mask-wearers became infected with Covid-19 and 53 of the non-mask-wearers: a small, non-statistically-significant difference.

The self-appointed Defenders of Science were quick to move into attack mode. Oxford’s Trish Greenhalgh said it was not necessarily “high quality science” and made some technical objections to the study; science-activists like Vincent Rajkumar, Editor-in-Chief of the Blood Cancer Journal, announced: “Ignore the Danish study. Masks work. Wear a mask… Speaking as someone who has led 10 RCTs and knows when to ignore one”; a former CDC director lambasted the study in the same journal that published it.

To make it worse, there were rumours that the study had been squashed or censored, rejected by medical journals on political grounds.

But in a sign of how rash this debate has become, none of the critics seems to have taken the time to talk to the study’s authors. We spoke to the lead investigator, Professor Henning Bundgaard of the University of Copenhagen, and found him to be the most inoffensive, on-message, pro-mask advocate you could find. It turns out that the scientist they were attacking was one of their own. His view, it turns out, is that:

  • Even though the protective effect is small, masks should be worn diligently wherever recommended.
  • The main benefit of masks is the ‘source control’ effect, where other people are protected from you, which the study does not cover.
  • The usefulness of the result is that it shows that you cannot be complacent even if wearing a mask — it must be seen as one tool among many, including social distancing, hand hygiene etc.
  • There was no conspiracy to censor his results: even though the study was rejected from the New England Journal of Medicine, JAMA and the Lancet, he does not believe it was for political reasons, more likely simply that it was a neutral conclusion.
  • He fully stands by his results and maintains that the study was carried out as scientifically as it is possible to do.
I think the message should be that wearing a mask, in the correct way of course, would to some extent — not a large extent but some extent — protect you. But it’s your contribution to protect others, that we should take care of each other. All of us would hate the idea that I had a dangerous disease now I passed it on to you because I was not wearing a mask. So we have good reasons to recommend masks, I guess.
- Professor Henning Bundgaard, University of Copenhagen

Not exactly someone worthy of the heavy-handed cancellation treatment.

Thanks to Professor Bundgaard for taking the time to talk to us, and clarifying his views.

Join the discussion


  • It may be worthwhile for some people to wear a mask, but the level of possible benefit (which isn’t statistically significant) does not warrant a mandate and punishment for not wearing a mask. Society is falling apart because masks are a wedge issue. It should be publicized far and wide that masks have a small benefit, so don’t shame anyone for not wearing it.

  • You don’t understand statistical analysis if you think there was a 25% difference between the masked and unmasked groups’ chances of catching Covid-19. Using the absolute numbers is not how the comparison can be measured. The percentage difference was 0.3%. This means there was no significant difference between the 2 groups. None. That’s what the p value of 0.38 tells us. And when a 95% CI for difference the crosses 0 (95% Confidence Interval is −1.2 to +0.4), it means there is just nothing to say. By all means wear a mask if it makes you feel better. But as of yet, there is still no evidence that a mask will make any impact at all on whether you do or don’t contract Covid 19.

  • And thats such an important question. Are asymptomatic carriers/cases capable of spreading? From the Track and trace experience of other countries it seems highly unlikely. it appears that this virus is now endemic so unless we answer that question we will end up locking
    and muzzling our entire population for a considerable period of time-vaccine or no vaccine

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