The question of whether face masks help against the spread of Covid-19 has been raging for months. Proponents from both sides have been throwing evidence (of often questionable sources) in each others’ faces since the beginning. Some politicians have even made things more confusing with their typically populist and unscientific opinions.
As with all things in science, however, we knew that there’s a “right answer” even if finding it might take some time. In this case, it’s becoming increasingly clear that face masks are indeed one of the best tools we have for softening the impact of the pandemic.
One of the more recent major pieces of evidence for that was a big meta-analysis of 172 studies published in The Lancet. The studies in it were all looking for different interventions for preventing the transmission of Covid-19, as well as SARS and MERS. According to the meta-analysis, the studies were very conclusive that masks help a great deal for slowing the virus.
Holger Schünemann is an epidemiologist at McMaster University and a co-author of one of the studies. As he puts it:
“What this evidence supports is that, if there is a policy around using face masks in place, it does actually come with a fairly large effect.”
With the novel coronavirus closing in on 10 million recorded cases and half a million deaths worldwide as of the end of June one might think that face masks would be the norm by now. Yet, anti-mask protests continue to be organized to the point where local health officials are even getting death threats for doing their jobs.
Still, alongside the public unrest, more and more studies come in support of face masks’ effectiveness. Jeffrey Shaman is an epidemiologist at Columbia University and he’s pointed out that while many of the studies in this and other meta-analyses are just observational and not 100% conclusive, they still make it clear just how effective masks are.
“I personally think that face masks are a key component of the non-pharmaceutical arsenal we have to combat COVID-19,” says Shaman.
Still, people’s skepticism is understandable even if the armed protests and death threats are well over the line. After all, in the beginning of the pandemic, it was both politicians and public health officials that spoke against the use of face masks. Nevertheless, even if we take the politics out of it, it’s normal in science for theories and hypotheses to change from time to time. That’s what makes science work – as new evidence comes out, new, more accurate theories are formed.
Why do masks help?
Researchers agree that there are two main reasons why face masks help slow down the spread of the pandemic:
- It protects the wearer of the mask from inhaling the airborne water droplets which carry the virus.
- It keeps the wearer of the mask from exhaling infected water droplets in public spaces and infecting others.
Some masks are better for the first task, and others – for the second, depending on their design and materials. Of course, no mask is 100% effective for either task. However, studies such as this one in Nature Medicine show that even simple cloth face coverings have been shown to have a noticeable effect on the amount of water droplets exhaled or inhaled.
Unfortunately, both of these factors are still largely misunderstood by the general public. A lot of people don’t realize that they can be asymptomatic carriers of the virus, for example. Others still think that the virus is only spread when you cough or sneeze and not when you’re just breathing or talking. That, of course, is incorrect and researchers such as Linsey Marr from Virginia Tech have already said as much:
“If you’re talking, when things are coming out of your mouth, they’re coming out fast. They’re going to slam into the cloth mask. I think even a low-quality mask can block a lot of those droplets.”
She also pointed to the study in Nature Medicine above as proof that even loose-fitting surgical masks will help in blocking the airborne water droplets we breathe in and out.
Masks have even been shown to be effective enough to stop the spread of the virus in households. Sure, this may seem like overkill to many people and most would rather not wear a face mask in their own home. However, this does speak to the effectiveness of face masks if they can even protect your family members whom you share your home with.
One study published in BMJ Global Health has looked at households in Beijing with at least one infected person. As Raina MacIntyre, one of the co-authors of the study explains it, at the time of the study it was already determined that most of the transmissions happened inside people’s homes. Thankfully, people in Beijing already had a culture of wearing face masks because of Beijing’s infamous air pollution problem. As a result, the study showed that wearing masks indoors even just as a precaution, brought the risk of infecting family members down by 79%.
“The more people that were wearing a mask, the more protective it was,” says MacIntyre.
It’s also important HOW you wear your mask
We’ve all seen people wearing face masks over their mouths but leaving their noses uncovered. It’s a very wide-spread practice but it renders the face masks almost useless. There are several reasons for this:
- This allows you to still inhale the virus through your nose.
- It also compromises the effectiveness of the mask as it no longer covers your chin and cheeks as well.
- It enables you to breathe out the virus and infect others.
A study published in the journal Cell has also suggested that Covid-19 is even able of establishing its presence in our nasal cavities. Another study, published in Proceedings of the Royal Society A, has also determined that if the wearing of face masks becomes more common and better executed, the spread of the disease can be halted much more effectively.
Linsey Marr also points out that while masks are not 100% effective, research has shown that together with other practices such as social distancing, they can be near-100% effective.
“From what I’ve seen, I would be comfortable sending my kids back to school if everyone’s wearing masks and they’re staying as far apart as possible,” Marr says.
It’s also worth noting what the differences between the various types of masks are. In general, N95 and N99 masks are best at protecting the wearer while other masks such as standard surgical masks or cloth face coverings are mostly good for protecting the people around the wearer.
However, since N95 and N99 masks are still in short supply, it’s still better (at least in most states and countries) if they’re reserved for healthcare and other essential workers. For those unable to acquire such a mask, surgical or other face masks are still strongly recommended to help slow down the disease. There’s ample laboratory evidence that even a surgical face mask offers ~75% protection from respiratory water droplets.
As for other, simpler masks and face coverings, their effectiveness can range from anywhere between 30% and 50% up to 75% depending on how they’re made. Masks with valves on the front are obviously to be avoided.
As May Chu, an epidemiologist from the Colorado School of Public Health points out in a paper in Nano Letters she co-authored household cloth materials can be quite effective at filtering air.
“I think we need a combination of [masks,] distancing, avoiding crowds, avoiding poorly ventilated spaces,” says Marr. “[Even if each of those individual measures is only partially effective] by the time you add them all on top of each other, you can achieve better numbers for reduction of transmission.”
How likely is it for people in the U.S. to improve their “face masks culture”?
Unfortunately, there does seem to be a very strong counter-culture to face masks in the U.S. that’s likely to persist regardless of how many hundreds or thousands more studies come out. And while this doesn’t bode well for the Covid-19 pandemic, it’s not all doom and gloom for the more long-term future.
The production of more N95 and N99 masks can make it easier for people to wear more effective and comfortable face masks in future Covid-19 waves or other pandemics. The main problem a lot of people today seem to have is that they don’t trust surgical or cloth masks so they’d rather not wear them at all.
Data from the spread of this first Covid-19 wave can also help inform the public more effectively in the future. Where this time politicians and health officials were split in the first months, next time there should be much less misinformation. That, together with better social distancing culture can make things significantly better.