Face masks and COVID-19

Your questions answered by La Trobe’s public health experts.

If you’re feeling confused about face masks at the moment, you’re not alone. Experts and health authorities are strongly recommending we wear them to reduce transmission of COVID-19, but governments have decided not to mandate them for now.

There’s lots of conflicting information about how effective they are and how much difference wearing a mask will make to the transmission of the virus during the current COVID-19 wave. And as we move away from mandated public health strategies to ‘personal responsibility’, it’s not even easy to figure out what type of mask to wear, where and when we should be wearing them and how we should handle them.

Here are some evidence-based answers to questions you might have about using masks.

How effective are face masks at preventing the spread of COVID-19?

The effectiveness of face masks is mainly determined by the filtration efficacy (fabric material) and facepiece leakage (fit). N95/P2 respirators are specifically designed to a standard that prevents 95% of particles from getting through them. Cloth and surgical masks filter out viral particles by having multiple layers - the efficiency of cloth masks varies depending on the type and structure of the fabric. Respirators fit tightly to the face whilst cloth and surgical masks can be loose, allowing air to enter around the edges.

In a community setting, without fit testing, a Californian study found people who reported always using a face mask or respirator in indoor public settings were 56% less likely to test positive to COVID-19 compared with people of the same age and gender who never wore a face mask. There was an 83% reduction in the chance of a positive test among those who wore a respirator, and a 66% reduction among those who wore surgical masks compared to wearing no mask. Cloth masks were substantially less effective than respirators or surgical masks.

Masks filter the virus-sized particles and can prevent further transmission as well as infection. This means they work best when everyone is wearing them. We can see this by observing the effect that population level masking has on the number of secondary cases arising from a single case each day - Rt. A positive Rt means the infection rate is growing, while a negative Rt means the infection rate is slowing. A study early in the pandemic found, after accounting for the influences of physical distancing measures and population characteristics, a 10% increase in self-reported mask-wearing was associated with a 3-fold increase in the likelihood of slowing transmission of the virus (negative Rt). A recent global study estimated that the observed level of mask wearing during mask mandates corresponds to a direct decrease in secondary infection rate of 19%, while perfect population mask wearing could lead to a decrease of 25%.

Which type of mask is best?

The best mask is the mask you will wear - consistently, every day you leave your house and are in indoor public spaces.

An N95/P2 respirator will give you the best protection. In community settings, KN95 masks are equivalent. Find a brand that fits tightly but still comfortably to your face. You may need to try a few different brands. There are some with loops around the head rather than the ears that may provide a better (or worse) experience.

If you can’t access a N95/P2 respirator, find the close fit difficult, really don’t want to part with your beard, or would just prefer to use the surgical masks that many places are providing free of charge – you can improve the fit of the mask and thus substantially increase its effectiveness by wearing a fitted cloth mask on top of the single use surgical mask.

How should I handle and care for my masks?

Most importantly, make sure the mask covers your mouth and nose, leaving no gaps.

Handle the mask only by the straps and sanitise your hands after touching it.

N95/P2 respirators and surgical masks can be re-used several times outside of healthcare settings. Hang your mask up to dry or store it in a paper bag for a few days between uses. Discard disposable masks if they get dirty, if the straps wear out or if you can no longer get a good fit.

Please make sure to dispose of used masks properly in a rubbish bin (and cut the straps so that small animals do not get tangled in them).

Cloth masks should be washed after each use in very hot water and hung to dry.

If masks are so effective, why haven’t they been mandated in more settings?

Mandating the use of face masks has been shown to increase the proportion of people who wear them, and to reduce COVID-19 cases, hospitalisations and deaths. A large 2021 study in the United States found that mask mandates reduced cases by up to 14%, deaths by up to 13% and hospital admissions by up to 7%. The introduction of a mask mandate in Melbourne in July 2020 lifted mask-wearing in public places from 43% to 97% (measured using images of public places) and resulted in a change in the growth rate of the epidemic from an increasing, to declining number of cases.

However, Australian political leaders have decided for now to strongly encourage people to wear masks, rather than mandating them in most settings.  In mid-July 2022, Victoria’s Health Minister decided against adopting advice from the Acting Chief Health Officer to mandate more widespread use of masks, despite the fact that the risk of reinfection and the continuous emergence of new COVID-19 variants indicate the increasing importance of mask wearing to prevent transmission. But if health systems become too strained and efforts to increase voluntary mask-wearing don’t work well enough, masks may yet be mandated.

What is La Trobe doing to promote mask-wearing?

La Trobe University is strongly recommending that face masks be worn on campus indoors and in outdoor settings where social distancing is not possible. Surgical masks are available from collection points on each campus.  If you opt for one of these masks, it’s best to wear a cloth mask over the top, or at least knot and tuck the mask to get a close fit and reduce gaps (see the video below for how to do this).

You could also consider purchasing your own N95/P2 masks. These can be found at Officeworks, Bunnings, and some pharmacies, or can be ordered in bulk from reputable online suppliers.

What else can I do to reduce my chances of catching COVID-19?

Further information about being COVID-Safe on campus can be found here.

Authored by Deborah Gleeson, Katrina Lambert, Caroline de Moel, Rwth Stuckey and Melissa Graham

Department of Public Health, La Trobe University