The Cochrane Report and Mask Efficacy

The Cochrane Report “Do Physical Measures Such as Hand-Washing or Wearing Masks Stop or Slow Down the Spread of Respiratory Viruses?” was published on 30 January 2023. (Jefferson et al. 2023). I have chosen two articles published by typically opposing outlets on the UK political spectrum from which to analyse how this report has been communicated to the public: The Daily Mail and The Guardian.

Cochrane is a “database of systematic reviews and meta-analyses which summarize and interpret the results of medical research.” (“Cochrane Library”, n.d.). Its reviews are “considered to be among the most reliable sources of evidence relating to clinical trials.” (Edwards et al. 2005). The Cochrane Report compiled the data of 78 randomised trials with over 610,000 participants, looking at the evidence for face masks and social distancing, hand washing and the sanitisation/sterilisation of surfaces. In a February interview, the report’s lead author, Tom Jefferson, senior associate tutor at the University of Oxford, “condemned the pandemic’s ‘overnight experts’,” and “criticised the multitude of scientifically baseless health policies.” (Demasi, M. 2023). The report’s key message is that: “We are uncertain whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses based on the studies we assessed. Hand hygiene programmes may help to slow the spread of respiratory viruses.” (Jefferson et al. 2023).

Many seem to have first learnt of this report in the New York Times article of 21 February, “The Mask Mandates Did Nothing. Will Any Lessons Be Learned?” by Bret Stephens. (Stephens. 2023). It also appears to have been disproportionately reported on by the US press – receiving barely a reaction by legacy media in the UK (“Altmetric Attention Score”, 2023).

An exception was the Daily Mail’s, “Does This Finally Put the Mask Debate to Bed?” by Caitlin Tilley, published just three days after the report itself (Tilley. 2023). Tilley is a US health reporter with the Mail. She was awarded the newcomer of the year award at the UK based Medical Journalists’ Association in 2022 and has a Master’s in Journalism.

Tilley’s piece has a notable subheading referencing the Danish DANMASK-19 study, the first trial of mask use during the Covid-19 pandemic, reported by many – Tom Jefferson included – as showing no significant effect for facemask wearers (Heneghan & Jefferson. 2020). Peter Hitchens claims his November 2020 Mail on Sunday column was one of very few accurate accounts of this, and asks, “If masks are pointless, will I get an apology?” (Hitchens. 2021). A sentiment echoed by Helena Kelly, also in the Mail, responding to the New York Times article with, “Has New York Times Ditched its Woke Mask?” A move she posits is “Sure to Infuriate Snowflake Staff.” (Kelly. 2023). DANMASK-19 is brought up further down in Tilley’s piece but does not reference the Editor in Chief of the British Medical Journal’s findings that the inconsistent and opaque methods by which social media platforms decide what can be published, allowed an inconclusive report to be skewed to fit anti-mask narratives (Abbasi. 2020).

Tilley disseminates the report with the aid of an infographic. She quotes two professors; one saying that the report indicates the benefit of wearing masks is “at best small,” the other that the report contained “very low‐certainty evidence.” She mentions that masks are a “prominent symbol of the Covid culture wars in the US.” Then gives some background history, speaking of the mixed messages about mask effectiveness from the authorities. She does inform the reader of the high risk of study bias and a difficulty to draw firm conclusions. Tilley sums up with some emotive reminders of the pandemic and poor public health communication. Ultimately, it is a summation for the layman, but with a clear ‘We Told You So’ vibe.

On 27 February, the Guardian published, “Don’t Believe Those Who Claim Science Proves Masks Don’t Work” by Lucky Tran (Tran. 2023). Tran is a US based science communicator with a PhD in Molecular Biology. His piece reminds us of the key role masks played in flattening the curve. He cites two 2020 studies that show masks work by reducing the emission of virus-laden droplets (Asadi et al. 2020 and CDC. 2021). Rather than distil down the Cochrane Report as gospel, Tran dissects it. He finds it deeply flawed as it not only mixes together studies involving different environments and risks, but also blends studies, looking at both influenza and Covid-19. Of the 78 papers analysed, only two studied Covid-19 masking.

Tran discredits both the report’s lead author and the writer of the New York Times article, calling them neither objective nor reliable. He says there is a “deliberate mischaracterisation” of the Cochrane review by data cherry-pickers with vested interests. He states that Covid-19 is still the third leading cause of death in the US – although that data is for January-September 2022 and half of Covid-19 deaths that year occurred January-February (Ortaliza et al. 2022). Is Tran therefore guilty of deliberate mischaracterisation? Is he himself reliable? He appeals to our human empathy, demands better studies and implores that we stop giving platforms to “bad faith actors.”

When it comes to reliability in science reporting (Nuccitelli. 2017), it’s important to remember that the Mail was banned as an unreliable source by Wikipedia in 2017 (Harrison. 2021). Wikipedia’s list of reliable sources describes the Guardian as generally reliable but warns that some editors regard it as biased and opinionated (“Reliable sources”, n.d.). Media Bias/Fact Check calls the Mail a questionable source with a low rating on bias and credibility (Huitsing. 2022, March); while the Guardian’s liberal bias in emotionally loaded – but often factual – information gives it medium credibility (Huitsing. 2022, September).

Tran is clearly frustrated with those who appear done with Covid-19 – as he pleads that it is not done with us. He is, however, just one voice and it could be argued that when others who give the Cochrane report little credence fail to vocally refute it, an impression of denial and dishonesty is presented, further validating their opponent’s argument. One need only read the comments on Tilley’s piece to see that anti-maskers have been vindicated. Perhaps this is why I did not recognise anything particularly manipulative or beyond dispute about how she presented the findings.

It could very well be that pro-mask outlets worry that informing their readers of this report would cast doubt on public health measures; but it seems that the curious will learn about it anyway, and more likely from a source with a proven anti-mask bias.




Abbasi, K. (2020, November 26). The curious case of the Danish mask study. The BMJ.

Altmetric Attention Score. (2023, January). Cochrane Library. (Retrieved March 7, 2023).

Asadi, S., Cappa, CD., Barreda, S., Wexler, AS., Bouvier, NM., & Ristenpart, WD. (2020, September 24). Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities. Nature.

Centers for Disease Control and Prevention (CDC). (2021, December 6). Use of Masks to Control the Spread of SARS-CoV-2.

Cochrane Library (n.d.) In Wikipedia. (Retrieved March 7, 2023).

Demasi, M. (2023, February 5). EXCLUSIVE: Lead author of new Cochrane review speaks out. Maryanne Demasi, reports.

Edwards, AM., Howell, JBL., Stevens, MT., Callaghan, B., Godfrey, S., Morikawa, A., Holgate, ST., König, P., Åberg, N., Stenuis-Aarniala, B., & Warner, JO. (2005, June 5). Quality of Cochrane reviews: assessment of sample from 1998. The BMJ.

Harrison, S. (2021, July 1). Wikipedia’s War on the Daily Mail. Slate.

Heneghan, C., & Jefferson, T. (2020, November 19). Landmark Danish study finds no significant effect for facemask wearers. The Spectator.

Hitchens, P. (2021, August 1). If the Danish Mask Study supported compulsory mask-wearing, why did the pro-mask media ignore its results? The Mail on Sunday.

Hitchens, P. (2023, February 18). PETER HITCHENS: If masks are pointless, will I get an apology? The Daily Mail.

Huitsing, M. (2022, March 23). Media Bias / Fact Check: Daily Mail.

Huitsing, M. (2022, September 10). Media Bias / Fact Check: The Guardian.

Jefferson, T., Dooley, L., Ferroni, E., Al-Ansary, LA., van Driel, ML., Bawazeer, GA., Jones, MA., Hoffmann, TC., Clark, J., Beller, EM., Glasziou, PP., & Conly, JM. (2023). Do physical measures such as hand-washing or wearing masks stop or slow down the spread of respiratory viruses? Cochrane Library.

Jefferson, T., Dooley, L., Ferroni, E., Al-Ansary, LA., van Driel, ML., Bawazeer, GA., Jones, MA., Hoffmann, TC., Clark, J., Beller, EM., Glasziou, PP., & Conly, JM. (2023). Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Library.

Kelly, H. (2023, February 23). Has New York Times ditched its woke mask? Now Gray Lady publishes opinion piece on ‘gold-standard’ study slamming mask mandates and asks ‘will any lessons be learned?’ – in move sure to infuriate snowflake staff. The Daily Mail.

Nuccitelli, D. (2017, February 13). This is why conservative media outlets like the Daily Mail are ‘unreliable’. The Guardian.

Ortaliza, J., Amin, K., & Cox, C. (2022, November 10). COVID-19 leading cause of death ranking. Peterson-KFF Health System Tracker.

Reliable sources/Perennial sources. (n.d.). Wikipedia. (Retrieved March 7, 2023)

Stephens, B. (2023, February 21). The Mask Mandates Did Nothing. Will Any Lessons Be Learned? The New York Times.

Tilley, C. (2023, February 2). Does this finally put the mask debate to bed? ‘Gold standard’ analysis of 78 studies and 1million people finds face coverings made ‘little to no difference’ to Covid infection or death rates. The Daily Mail.

Tran, L.  (2023, February 27). Don’t believe those who claim science proves masks don’t work. The Guardian.

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