Masks in hospitals made ‘no difference’ to Covid infection rates, study finds

Masks made ‘no discernible difference’ to Covid transmission rates in hospitals, new research suggests.

Infection rates didn’t soar when mask mandates were removed in NHS facilities during the middle of an Omicron surge.

Experts today said the findings did not mean face coverings are ‘worthless’.

But they called for ‘rational and proportionate’ masking policies in hospitals during future Covid flare-ups because the benefits are ‘at best, modest’.

Governments around the world — including the UK — made it mandatory to wear a face covering in indoor public spaces.

Researchers found removing the mask policy in phase two did not produce a ‘statistically significant change’ in the hospital acquired Covid infection rate. Equally, they ‘did not observe a delayed effect’ in the Covid infection rate once the policy was removed, the study added

This was despite a dearth of rigorous trials into their effectiveness.

Some hospitals still call for patients to cover up before entering, although it is no longer legally required.  

Researchers from St George’s Hospital in south-west London analysed routinely collected infection control data over a 40-week period between December 4, 2021 and September 10, 2022.

It marked the time between the first week Omicron became the dominant Covid variant and the week universal PCR Covid screening tests were scrapped for patients being admitted.

During the first phase of the study – December 4, 2021 to 1 June 2022 – all staff and visitors were required to wear masks in both clinical and non-clinical areas.

By phase two, the mandate was removed.

Instead, decisions about mask policy were entrusted to individual hospitals.

High risk wards, including ones treating cancer patients and intensive care units, retained the mask obligation.

Researchers found removing the mask policy in phase two did not produce a ‘statistically significant change’ in the hospital-acquired Covid infection rate.

Equally, they ‘did not observe a delayed effect’ in the Covid infection rate once the policy was removed.

This was despite transmission of the virus spiking within the community.  

Those in high risk wards – the control group – who continued wearing masks, also ‘found no immediate or delayed change in infection rate’, the study said.

While initially viewed as a virus prevention measure, masks have become a prominent symbol of the Covid culture wars in the UK.

Officials issued mixed messages about their effectiveness at the beginning of the pandemic.

Studies failed to show definitively that masks prevented Covid.

In February, one of the most comprehensive meta-analyses of face coverings to date, by the Cochrane Institute, revealed masks made ‘little to no difference’ to Covid infection or death rates.

As with any observational study, researchers behind the new UK study warned there were potential limitations.

Those in high risk wards – the control group – who continued wearing masks, also ‘found no immediate or delayed change in infection rate’, the study said 

These included not being able to determine staff infection rates and not assessing adherence to the mask-wearing policy.

Lead author Dr Ben Patterson said: ‘Our study found no evidence that mandatory masking of staff impacts the rate of hospital SARS-CoV-2 infection with the Omicron variant.

‘That doesn’t mean masks are worthless against Omicron, but their real-world benefit in isolation appears to be, at best, modest in a healthcare setting.’

Fellow researcher Dr Aodhan Breathnach added: ‘Many hospitals have retained masking at significant financial and environment cost and despite the substantial barrier to communication.

‘We hope this empirical evidence can help inform a rational and proportionate mask policy in health services.’

The research will be presented later this month at the European Congress of Clinical Microbiology & Infectious Diseases in Copenhagen, Denmark.