Do Masks Really Help Against COVID-19?

For reasons that I do not understand at all, the issue of wearing face masks has become political.  It should not be political – this doesn’t make sense.  This is a science, health, and epidemiology issue.

But do they really help in slowing down the spread of COVID-19?  Are they really necessary?

Let’s start by briefly describing the three main types of face masks that are used.  Each serves a similar function, but they do differ slightly in terms of availability and recommended use.

Surgical Masks

N-95 Respirators

An N-95 respirator is a tight-fitting mask that does serve a different function when compared to surgical masks.  To be used correctly in a clinical setting, an N-95 respirator actually has to be fitted to the wearer to ensure that there is an airtight seal.  Of course, this is not typically done in a community setting, which would render the masks a little less effective.  This type of mask does filter very small particles – the name “N-95” means that they are rated to filter out 95% of very small particles (as small as 0.1-0.3 microns), which would include viruses.  As opposed to a surgical or cloth mask, then, an N-95 can protect the wearer of the mask from inhaling virus particles. 

Cloth Mask

These can be homemade or store-bought, and can be thought of in the same way as surgical masks.  Their main purpose is to block larger particles and droplets that come from the wearer of the mask.  They do not filter smaller particles such as viruses.

So do they work?

In a word – yes.  They are not perfect or fool-proof, and I frankly don’t believe any report that touts that masks will “eliminate this virus” or “stop COVID-19 in its tracks.”  Wearing masks, though, can absolutely slow the spread of COVID-19.  There are a lot of recent studies and observations that support this, but I’ll just highlight a couple of interesting ones below.

There was a recent article in the Journal of the American Medical Association (JAMA) that described the impact that mask usage has had among hospital workers at Mass General Brigham Hospital (MGB).  MGB started by doing systematic testing of healthcare workers at their hospital.  Then, a universal masking procedure was implemented for the hospital – this means that all healthcare workers and patients were required to wear masks.  It should be noted that surgical masks were worn, not N-95 masks, which in my opinion makes this study more applicable to daily life.  Prior to the masking intervention, the rate at which healthcare workers tested positive was exponentially increasing, and at it’s peak the test positivity rate was at 21.32% (this means that of all the SARS-CoV-2 tests performed on healthcare workers, 21.32% of them returned positive for the virus – this is a lot!!).  After the universal masking mandate, the positivity rate decreased markedly, down to 11.46% at the end of the study, and was continuing to decline.

OK, statistics can be confusing – I get it.  A lot of times I have to stare at numbers like these for a while before the meaning starts to sink in (a little…).  This is one case where a picture really drives the point home.  Here is a graph that depicts the study results.  There are a lot of dots and numbers, but what I really want you to pay attention to is the curved line on the left – going upwards – and then the straight line on the right – going downwards.  The curved line on the left   (in the pink portion) shows the positivity rate before everyone started wearing masks – you can see that it is exponentially increasing over time.  The purple and yellow portion in the middle represents the period of time that the intervention – mandating masks for healthcare workers and patients – took place.  The straight line on the right (in the green portion) shows what happened to the positivity rate after the intervention.  As you can see, it is steadily decreasing.  Look at the difference in those two lines – it’s pretty dramatic.  It should also be noted that during the time frame that this study took place, the local case rate for COVID-19 continued to increase in the MGB area.  This means that while the numbers of cases locally was continuing to increase, MGB was able to achieve a substantial decrease in positivity rates among healthcare workers at their hospital – just by wearing surgical masks.

A second example is more observational, but still illustrates a real-world example of the effectiveness of wearing masks.  This one involves a hair salon in Missouri.  Two stylists at this salon developed respiratory symptoms, but continued to work and see clients.  They both worked for about 8 days – while having respiratory symptoms – until their test results returned positive for SARS-CoV-2.  During those eight days, the two stylists served 139 clients.  During this time frame, both the stylists and their clients wore masks continuously – a vast majority of these were either surgical masks or cloth masks, with only a minority (less than 5%) being N-95 masks.

The interesting thing?  Even thought the stylists were symptomatic, none of the 139 clients developed symptoms compatible with COVID-19 in the 14-day quarantine period that followed.    All of the exposed clients were offered testing, and 48% of them underwent testing – all tested negative.  Even more interesting is the fact that almost all of the household contacts of the two stylists developed symptoms compatible for COVID-19 and eventually tested positive.  What does this tell us?  These two individuals had symptoms and were actively transmitting the virus (hence, their household contacts eventually contracted the virus), but transmission to clients was prevented.  The difference?  Face masks.

Final thoughts

In medical practice, I will frequently discuss a risk/benefit ratio with my patients.  This can be applicable to many situations – a new medication, a surgical procedure, a diagnostic test, etc.  Basically, any intervention can carry some risks.  There are also the benefits of the intervention to consider.  Whether or not to proceed with the intervention largely depends on the risk/benefit ratio – for example, do the benefits expected from this new medication outweigh the potential risks of being on the new medication?  If the benefits outweighs the risks – or if the risks are truly minimal – then proceeding with the intervention might be the best choice.

Let’s apply this concept to wearing masks.  What are the risks to wearing masks?  From a medical standpoint, there are basically no risks or downsides.  They aren’t exactly comfortable or stylish, perhaps there’s some social discomfort to wearing them, and they can be a pain to keep track of.  But are there any health risks?  Not any significant ones in my opinion.  Now, I understand that there are many individuals with lung conditions that cause wearing a mask to be uncomfortable, and increase the sensation of being short of breath.  Many of my own patients fall into this category, and trust me – I hear you.  But the fact of the matter is that, looking at medical data and facts, wearing a cloth face mask or surgical mask has never been shown to worsen any underlying lung condition.  The concerns for lower oxygen levels and retention of carbon dioxide (CO2) is mostly associated with N-95 masks, not at all with surgical or cloth masks.  I can definitely understand feeling uncomfortable in an N-95 mask, which are tighter fitting with much smaller pores, but these aren’t needed – a surgical mask or cloth mask would be just fine.

So what about the benefits of wearing masks?  The two illustrations above give good examples of the tangible benefits of wearing masks.  A recent article published in Nature estimates that about 530 million cases of COVID-19 have been prevented or delayed globally by wearing masks, and 60 million of those are in the U.S.  More numbers and statistics and studies can be cited, but if I’m honest, I think this comes down to more than that.  It certainly shouldn’t be a political issue.  It’s a social responsibility – and perhaps even moral – issue.

Here’s what I mean.  A vast majority of people who contract COVID-19 will have very mild symptoms.  But there is a more vulnerable population who has the potential to get very sick, and for whom this infection might prove fatal (and it’s difficult to determine who might get very sick – see my previous post on this topic).  Furthermore, the more rapidly COVID-19 spreads, the more rapidly our hospital systems and resources get overwhelmed, which brings a host of other logistical/financial/economic/public health problems.

For the purposes of slowing down this virus, though, mask wearing does not work “piecemeal.”  It’s not only the medically vulnerable who need to wear masks, but everyone – including those who would get very mild symptoms.  That’s how we slow the spread, “flatten the curve,” and protect others.  So we are asking the lion’s share of the population to inconvenience themselves a little for the sake of the vulnerable.

Perhaps, if we are honest with ourselves, that is the main “risk” that we feel on the issue of wearing masks – the inconvenience of it.  So we all have to ask ourselves – does this risk outweigh the benefits?  I will be the first to grant you that mask-wearing isn’t perfect, and won’t make COVID-19 disappear.  If everyone wore masks, the SARS-CoV-2 virus will still be around, and it will still spread – I want to make that clear.  However, I think it’s also clear that the rate at which it spreads will be drastically reduced, and it absolutely stands to reason that we can prevent many vulnerable people from contracting COVID-19 with this intervention.  Both of these issues – slowing the spread (or “flattening the curve”) and outright prevention of infection – are powerful tools against a virus that spreads quickly.  If you believe that this benefit might be only minimal in the grand scheme of things, couldn’t even a small benefit still be worth it, considering the downsides?

A lot of the people that I care for, both in clinic and in my personal life, fall into the category of “medically vulnerable” as it relates to COVID-19.  So for me, it’s pretty clear that the benefits of wearing masks outweigh any perceived risks.  I will continue to wear a surgical mask in public.

I’ll leave you with a quote from CDC Director Robert Redfield: 

“At this critical juncture when COVID-19 is resurging, broad adoption of cloth face coverings is a civic duty, a small sacrifice reliant on a highly effective low-tech solution that can help turn the tide favorably in national and global efforts against COVID-19.”