Daily washing of cloth masks required to reduce virus transmission

Facemasks: two layers a minimum, three layers best

While some parts of the country face the prospect of wearing face masks into the foreseeable future, as the face mask rules came into effect many people have relied on scarves, bandanas, face shields and even cycling Buffs as a way to protect themselves from the Covid-19 virus.

However, it has been reported that these face mask “concessions” that were made “as we adjusted to this new normal” will reportedly “no longer apply”, with people now required to “wear a fitted mask covering the nose and mouth”.

In addition to scarves, bandanas and face shields, as the need to wear face masks came into effect so did the rise of reusable, cloth masks – which are largely fitted and cover the nose and mouth.

While reusable, cloth masks may be preferred as a more economical option rather than purchasing disposable surgical masks, a new publication from researchers at UNSW Sydney advises daily washing of cloth masks to reduce the likelihood of contamination of viruses like Covid-19.

New analysis from the Kirby Institute at UNSW Sydney published in BMJ Open suggests that cloth masks must be washed daily, at high temperatures to be protective against injection.

“Both cloth masks and surgical masks should be considered ‘contaminated’ after use,” says Professor Raina MacIntyre, who conducted the study.

“Unlike surgical masks, which are disposed of after use, cloth masks are re-used. While it can be tempting to use the same mask for multiple days in a row, or to give it a quick hand-wash or wipe-over, our research suggests that this increases the risk of contamination.

“Given the potential implications for health workers or community members who are using cloth masks during the pandemic, we did a deep dive into the 2011 data on whether the health workers in our study washed their masks daily, and if so, how they washed their masks.

“We found that if cloth masks were washed in the hospital laundry, they were as effective as a surgical mask.”

As part of the study the researchers analysed unpublished data from a randomised controlled trial (RCT) they published in 2015. This study is still the only RCT ever conducted on the efficacy of cloth masks in preventing viral infections.

It is important to note that given the study was conducted over five years ago, the researchers did not test for Covid-19 – instead, they included common respiratory pathogens such as influenza, rhinoviruses and seasonal coronaviruses in their analysis.

It is based on self-reported washing data and was conducted by health workers in high risk wards in a healthcare setting.

“While someone from the general public wearing a cloth mask is unlikely to come into contact with the same amount of pathogens as healthcare worker in a high risk ward, we would still recommended daily washing of cloth masks in the community.

“Covid-19 is a highly infectious virus, and there is still a lot that we don’t know about it, and so it’s important that we take every precaution we can to protect against it and ensure masks are effective,” says Professor MacIntyre.

According to the analysis, handwashing the masks did not provide adequate protection.

Healthcare workers who self-washed their masks by hand had double the risk of infection compared to those who used the hospital laundry.

The majority of people in the RCT handwashed their masks, and this may be why the cloth masks performed poorly in the original trial.

“The WHO [World Health Organisation] recommends machine washing masks with hot water at 60 degrees Celsius and laundry detergent, and the results of our analysis support this recommendation,” says Professor MacIntyre.

“Washing machines often have a default temperature of 40 degree or 60 degrees, so do check the setting.

“At these very hot temperatures, handwashing is not possible.

“The clear message from this research is that cloth masks do work – but once a cloth mask has been worn, it needs to be washed properly each time before being worn again, otherwise it stops being effective.”

To read the study, visit: bmjopen.bmj.com/content/10/9/e042045