Masks cut risk by 53%, distance by 25%, study review finds

Passengers wearing face masks on the Luas in  Dublin. A review of studies has claimed that when it comes to mask-wearing, "overall pooled analysis showed a 53% reduction in Covid-19 incidence".

Mask-wearing and social distancing offer protection against Covid-19, with masks reducing risks by 53%, a review of global studies has found.

The review, published in the British Medical Journal yesterday, found a 25% reduction in Covid incidence due to social distancing.

However, while some Irish healthcare workers welcomed the analysis, they cautioned the findings are not clear-cut. Indeed, the British Medical Journal ran a parallel editorial titled ‘Lack of good research is a pandemic tragedy’.

Led by Stella Talic at Monash University, Australia, the review found: “Several personal protective and social measures, including hand-washing, mask-wearing, and physical distancing are associated with reductions in the incidence of Covid-19.”

They started with more than 70 studies, which were whittled down to 14 due to the lack of detail in many.

Six studies with 2,627 people with Covid-19 and 389, 228 participants on mask-wearing were included, and they found: “Overall pooled analysis showed a 53% reduction in Covid-19 incidence.”

Nurse Deirdre O'Mahony reminding the public to keep wearing their masks. Picture: Brian Lougheed

They included five studies with 2,727 people with Covid-19 and 108,933 participants on social distancing, finding: “Overall pooled analysis indicated a 25% reduction in incidence of Covid-19.”

They found only three good studies on hand-washing and said while these showed a 53% reduction in incidence, this is “not statistically significant” due to the small numbers.

The review, titled 'Effectiveness of public health measures in reducing the incidence of Covid-19, SARS-CoV-2 transmission, and Covid-19 mortality: Systematic review and meta-analysis', states that tougher measures, including full lockdowns, are not sustainable. 

It also states that, despite high vaccination rates in some countries, vaccines are not 100% effective against transmission, and mask-wearing and other measures are likely to remain important, particularly in countries with low vaccine uptake.

Public health consultant Niall Conroy said it is “amazing progress” to see this analysis.

However, he added: “I think it is important for people not to pull the pieces that they’re ideologically tethered to out of this study to increase the 'follow the science' noise in the pandemic space.”

Dr Conroy, who is currently working in Australia, welcomed the findings around masks, and said the conclusion that hand-washing seems to be beneficial is also “reassuring”.

Posting on social media, he said the finding around social distancing “looks about right” based on his experience, but said it is important to remember that in the real world, people do not always stick to the rules.

Ray Walley, from the national Covid-19 GP liaison committee, said: “This [masks] is as, if not more, important than antigen tests, this is mitigation."

He said the Health Information and Quality Authority should be asked to review the evidence around mask-wearing for children. Hiqa last published on this in September.

Dr Talic’s review team only found one study looking at the impact of disinfecting surfaces.