A large study by researchers from Harvard Medical School in the US has identified a strong increase in cases of respiratory infections caught in hospitals after COVID-19 measures such as masks were removed.

The study, led by Dr Theodore Pak from Massachusetts General Hospital in Boston, tracked data from over 64,000 patient admissions between late 2020 to early 2024.

According to the data, there was a 25% increase in hospital-onset respiratory infections when masking and testing measures were removed in May 2023.

However, hospital-onset infections dropped by 33% in January 2024 when the Mass General Brigham healthcare system reimplemented mask mandates for healthcare workers.

The research, published in JAMA Network Open, focused on three key respiratory infections, COVID-19, influenza and RSV.

Hospital-onset infections, for this study, refer to any infections that were detected 4 days after a patient was admitted. Whereas community-onset infections referred to infections where the patient tested positive within 4 days of admission.

Across the 10 hospitals analysed, there were 30,071 cases of community-onset respiratory infections and 2075 hospital-onset infections.

The authors say that these results demonstrate that a universal mask mandate and regular testing could be the key to protecting patients in hospital and healthcare settings.

“Our study would support the use of targeted universal masking, which I think is potentially more palatable from a cost perspective than re-instituting universal testing, and it is something that we will hopefully do in our own hospital system as well as case counts pick up again,” Pak said in an interview with MedPage Today.

Australian epidemiologists broadly agree with the need for masks in hospital settings but are wary of mandates.

Dr Stefanie Vaccher,  senior research fellow at the Burnet Institute in Melbourne says the study reinforces the value of COVID-19 hygiene, saying  that masks are one element of a broader infection control strategy.

“The important thing about masks is that it’s one piece of the toolkit.”

She also argues for ventilation, good hygiene and making sure everyone is up to date with their vaccinations.

“It’s using the right tools in different situations and tailoring your approach depending on where you are and what you’re doing.”

Vaccher also explains how previous research into the efficacy of masks has come across some challenges.

“Where there are mandates in particular, healthcare workers are wearing masks and they’re more likely to be wearing masks correctly.”

“But for instance, in the general public, I’m sure you’ve seen, people don’t wear their masks properly. They might be upside down, they might be not covering their nose, they might be too open.”

“So does that count as wearing a mask or not? And it can be really hard to try and assess that,” say Vaccher.

For Hassan Vally, Associate Professor in Epidemiology at Deakin University, making masks available is a part of the ongoing approach to prevent the spread of infections across healthcare settings.

“The wearing of high-quality masks adds an extra layer of protection in high risk settings and there is still an important role for their use in the prevention of the spread of covid.”

“I think in western societies the covid pandemic was transformative in terms of the acceptability of mask wearing in society,” Vally told Cosmos.

“The decision to wear a mask in broader society is now largely one that is based on individual considerations. That is, it is based on an individual’s assessment of their risks of severe illness as well as the setting and more broadly on the level of virus circulating in the community,” says Vally.

However, Valley acknowledges the difficulty of mask mandates.

“There are challenges associated with enforcing mandates for any covid preventative measure given where we have been and where we are now in our journey over the past few years.”

“Whilst mandates and whole of society interventions like lockdowns were appropriate and largely accepted by the public in the early years of the pandemic, we need to be very careful in the use of mandates of any type given how the risk calculus has changed,” he says.

Vaccher agrees.

“I think mandates, especially around masks in the general public, are very hard to enforce and I don’t think they would be particularly well received. 

“In a healthcare setting though, given the infection risks, I think you could try and enforce that a little bit more.”

“If you are sick and you are going to a doctor or some other kind of health facility, a mask is a really excellent thing to be using,” Vaccher says.

“Even if you don’t think you’re sick but going to see your grandma in a nursing home, there’s no harm in putting one on.”

Masks outside hospitals are a different matter