According to a new study based on statistical models, face masks can play a key role in reopening our society without risking a sweeping second wave of infections.

“Our analyses support the immediate and universal adoption of face masks by the public,” said Richard Stutt, who co-led the study at Cambridge.

“All models are wrong,” a common aphorism in statistics goes, “but some are useful”.

We’ve seen over the course of the pandemic that some statistical models turn out to wildly wrong, but here’s the thing: models aren’t necessarily meant to be right — oftentimes they’re meant to give us an idea of what could happen under different scenarios.

In the new model, researchers wanted to see how different lockdown and face mask behaviors would affect disease transmission. The research showed that lockdowns do help, but they’re not a sufficient measure to prevent a second wave. The model also showed that if sufficient people wear face masks in public, transmission can be substantially reduced and a second wave can be averted.

“If widespread facemask use by the public is combined with physical distancing and some lockdown, it may offer an acceptable way of managing the pandemic and re-opening economic activity long before there is a working vaccine.”

Keeping R < 1

If we want to keep the disease in control, we have to ensure that the number of cases isn’t growing. The infamous ‘reproduction number’ or R0 (which indicates how many new infections are caused by an existing infection) must be kept under 1 to keep the outbreak under control. If the number is over 1, then the number of infections is rising, and we’re at risk of new outbreaks.

The study’s modeling included all stages of infection and transmission from the air as well as contaminated surfaces. Unlike other previous models, researchers also considered the negative aspects of mask use, such as increased face touching.

“We show that, when facemasks are used by the public all the time (not just from when symptoms first appear), the effective reproduction number, can be decreased below 1, leading to the mitigation of epidemic spread. Under certain conditions, when lock-down periods are implemented in combination with 100% facemask use, there is vastly less disease spread, secondary and tertiary waves are flattened and the epidemic is brought under control.”

Want fewer lockdowns? Wear a mask

Of course, it’s a virtual impossibility for 100% of people to wear face masks (and all models are wrong, remember), but this is a good indication of how useful masks can be. For instance, if everyone would wear masks, and the masks were only 75% effective, it would still be enough to bring a very high R number of 4 (which was the case in the UK or New York before the lockdown) to under 1 — even without any lockdowns.

Even masks that only offer a droplet capture of 50% still offer significant and widespread benefits. In all scenarios in the study, face mask use by 50% or more of the population reduced R below 1, flattening future disease waves and allowing for less stringent lockdowns.

Wearing masks is a selfless act

In fact, another notable takeaway from the study is that even if people wear masks improperly (for instance, by repeatedly touching the outside of the mask, which actually raises the wearer’s risk), masks can still have a positive impact. Even if people wear masks so improperly (which can end up quadrupling the wearer’s risk of infection), the net effect is still positive as long as enough people wear them.

Of course, the idea is to wear masks properly and use them to protect yourself as well, but this is a testament to how useful masks can be. In fact, researchers say, the primary role of a face mask is not to protect you from others, but rather to protect others from you.

Sure, face masks can also offer some protection to the user, but wearing face masks is primarily a selfless act. You wear masks to protect others, and others wear a mas to protect you.

“There is a common perception that wearing a facemask means you consider others a danger,” said Professor John Colvin, coauthor from the University of Greenwich. “In fact, by wearing a mask you are primarily protecting others from yourself.”

“Cultural and even political issues may stop people wearing facemasks, so the message needs to be clear: my mask protects you, your mask protects me.”

The researchers have also criticized the UK’s approach to face masks. Just 1 in 5 Brits support the wearing of face masks, compared to approximately 70% of Americans, for instance. Furthermore, the UK government has only recently decided wearing face masks to be mandatory on public transportation — whereas other European countries have generally imposed the wearing of masks in far more situations.

“In the UK, the approach to facemasks should go further than just public transport. The most effective way to restart daily life is to encourage everyone to wear some kind of mask whenever they are in public,” Colvin said.

Ultimately, an important takeaway is that improvised face masks (such as the ones you would make yourself from textiles, or buy) can be of tremendous help. They may very well make the difference between a flattened or a devastating second wave.

The study can be read in its entirety here.