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FACTCHECK

Debunked: Recent studies indicate masks can be effective at preventing the spread of disease

A 2022 study on mandates for Catalan schoolchildren had been touted as proof masks don’t work.

For general Factchecks not about Covid (2)

NUMEROUS CLAIMS ONLINE have suggested that recent scientific studies on face-masks have shown that they are ineffective at preventing the spread of viral disease.

Similar posts published on the Twitter and Facebook accounts of Irish radio presenter Niall Boylan read: “Two years ago people who didn’t agree with wearing masks were vilified, called anti-maskers, right wing nut-jobs and actually fined.

“Now all the evidence and all the latest published studies clearly show they were right and masks make and made no difference.

“So when do we get an apology and will those who were fined get a refund as the fine was based in a law that was misinformed.”

But a survey of a number of recent studies by The Journal found seven of them that suggested masks were effective at stopping the spread of respiratory diseases, such as Covid-19, and none that suggested that they were not.

There are other, older studies that are cited, which were unable to find a strong effect for mask mandates on rates of diseases, such as a Cochrane review of randomised controlled trials.

However, the publishers of that review explicitly said that it should not be implied that their review means masks are ineffective.

Boylan has railed against Covid restrictions since the start of the pandemic, describing lockdowns as draconian.

“Covid has become a religion which tells people to live by their rules or go to hell,” he said in a now-deleted tweet. “If you don’t live by the new government rules you might kill your family.”

During this time he also spread now-debunked theories about violence at anti-lockdown protests and hosted conversations with anti-mask activists, including Professor Dolores Cahill, who has also claimed incorrectly that masks cause brain damage and that vaccines for Covid-19 would kill or maim everyone who took them within a year.

Boylan has not responded to The Journal’s request for comments by the time of publication. 

‘Made no difference’ 

In an online conversation underneath his tweet on masks, Boylan provides a source for his claims that masks “made no difference”: a study of school children in Catalonia, Spain.

The study claimed that “mandates in schools showed no significant differences in terms of transmission”.

Researchers compared Covid rates in children aged three to five years old in preschool, where masks weren’t mandated, with children aged six to 11 years old, who had entered primary education and were supposed to wear masks.

The study also claimed that “age is a key component explaining transmission in children”, even within these groupings.

Statistics cited in the study suggested that five-year-olds were more likely to get Covid than three-year-olds, despite neither age group having mask mandates, and that 12-year-olds were more likely to contract Covid than six-year-olds, despite both age groups having mask mandates.

COVID ratesinCatalonia Mean secondary attack rate (SAR) and effective reproductive number (R*) with 95% CI by school year (P3–P5 for preschool and years 1–6 for primary education).

The figures provided by the study show that the reproduction and the secondary attack rate – the probability an infection occurs among susceptible people within a specific group, such as within a household or close contacts  – were both lower in year 1 of primary education, where mask mandates apply, than in the final year of preschools, where they don’t, though the researchers said this drop was “not statistically significant”.

However, the study also contains a number of caveats.

Researchers specifically noted that there were limitations to their paper, which is a review of already-collected data rather than a randomised controlled trial, something considered “the gold standard for effectiveness research”.

It also applies to two specific age groups in Catalonia schools, rather than the wider population.

The researchers said they couldn’t take into account differences in students’ behaviour, the density of students in classrooms, or the classroom dynamics between those in preschool and primary school.

It is unclear whether such a study can be extended to show that masks in general “make no difference” particularly when the researchers say the school children involved may have worn masks incorrectly.

Another study that has recently been widely miscited as showing that masks are proven not to work was a review of data collated from 78 trials and published by Cochrane, a well-respected healthcare research network.

However, as a FactFind by The Journal showed, the study’s results do not imply masks are ineffective, and Cochrane has since confirmed that their study should not be interpreted that way.

“Many commentators have claimed that a recently-updated Cochrane Review shows that ‘masks don’t work’, which is an inaccurate and misleading interpretation”, a statement released by Cochrane said.

“It would be accurate to say that the review examined whether interventions to promote mask wearing help to slow the spread of respiratory viruses, and that the results were inconclusive.

“Given the limitations in the primary evidence, the review is not able to address the question of whether mask-wearing itself reduces people’s risk of contracting or spreading respiratory viruses.”

‘All published studies’

Boylan’s claim more boldly asserted that just one or two studies showed the supposed ineffectiveness of face-masks. He said: “Now all the evidence and all the latest published studies clearly show [...] masks make and made no difference.”

A review by The Journal of the 50 most recent search results involving terms like “covid”, “masks” and “effectiveness”, published on PubMed – a search engine that collates research summaries, and which Boylan had linked to for the Catalan study – shows that there are multiple studies published in the last two months showing masks to be effective, or likely to be effective.

None of the 50 results reviews by The Journal directly suggested masks are ineffective at stopping the spread of disease, though some did mention other negative effects of masks, such as a possible increase in headaches in healthcare workers, or environmental damage from discarded masks.

(Neither the Cohrane study, published in January 2023, nor the Catalan study, which was first published in August 2022, were included in this search results for the 50 most recent studies).

Recent studies have indeed provided evidence that masks are effective at preventing disease, contrary to Boylan’s social media posts.

Several previous studies from earlier in the pandemic also back up the effectiveness of mask-wearing to prevent Covid and other airborne diseases.

The Journal’s FactCheck is a signatory to the International Fact-Checking Network’s Code of Principles. You can read it here. For information on how FactCheck works, what the verdicts mean, and how you can take part, check out our Reader’s Guide here. You can read about the team of editors and reporters who work on the factchecks here.