Medical face masks and Coronavirus, will they protect me? Let’s discuss the veracity of such an important issue as well as its different types.
- 1. Current situation
- 2. Control measures
- 3. What are medical masks or face masks
- 4. Medical masks
- 5. Respirators
- 6. Can face masks help to prevent infections?
- 7. Differences between exposures to pathogens
- 8. I have made a super-effective homemade face mask
- 9. Cloth face masks
- 10. What is better, a respirator or a medical mask?
- 11. Manipulation of respirators
- 12. More controversies
- 13. Should I use a mask?
- 14. Official Statements
- 15. Bibliography
- 16. Related Entries
Right now, the SARS-CoV-2 has caused more than 16 362 deaths. With an infection curve that is dangerously increasing as the disease spreads.
Figure I. World infection curve since January 22.
One of the measures to prevent the spread of COVID-19 is using PPE (personal protective equipment).
From this group, face masks are the ones that are what are causing more concern.
I do not know if this is due to the perception of their efficacy, price or accessibility. Perhaps it is simply because it is a common accessory in healthcare and people have seen it in movies and TV shows.
Figure II. Image from the TV show House MD where we can see a medical mask.
What are medical masks or face masks
Face masks are a personal protective equipment that cover the airways, preventing the pathogens from entering our body. They are also known as respiratory protection devices or RPDs.
Are all of them the same?
No, they are not
The classic face mask of a doctor like the one from the previous picture is a medical mask. But they have to labelled depending on their use: dental, isolating, surgical…
It is part of the personal protective equipment of a healthcare professional in order to avoid being exposed to a pathogen that can be transmitted through the droplets from the mouth and nose from others.
It can also be used in order to avoid spreading the disease to others with your own oronasopharyngeal fluids.
Figure III. Image from the TV show House MD
On the contrary, respirators are protective devices that are used to protect the wearer from air pollution.
These accessories provide more protection against pathogens which can cause infections through aerosols. They are classified depending on their ability to filter specific particles in standardized tests:
The popular N95 means that it filters a 95% of said particles.
- If the respirator is labelled with an R, it means that it is resistant to small oil droplets (1-10mcm);
- If it is labelled with a P, it means that it is extremely resistant.
That is, these devices are ready to face infectious bio-aerosols and contaminants with a small particle size.
Figure IV. Worker wearing a respirator.
Can face masks help to prevent infections?
Yes, at least it seems that there is a positive trend.
In other words, face masks are a real and effective physical barrier against specific pathogens.
Limitations of the studies
Many of them are observational, they do not perform serological tests and they determine the result according to the symptomatology.
Others do not have a control group, they do not take into account the transmission features of the pathogen, or the type of exposure from the sample…
Still, we can have a look at the meta-analyses like the ones by Jefferson et al., (2009). He concluded that wearing a face mask lowers the risk of infection, which was even more effective than other strategies like washing our hands frequently.
Figure V. Tree diagram about the effects of washing our hands frequently and using face masks among healthcare professionals. The result was that those who use these strategies have lower chances of being infected.
Therefore, “wearing a face mask” lowers the risk of suffering an acute respiratory syndrome.
Differences between exposures to pathogens
Not all viruses are the same.
When we talk about a virus like influenza (the flu), the results are quite controversial.
There does not seem to be a homogeneous reduction of the amount of infections caused by the virus. In fact, the positive tendency is associated with the use of face masks and other PPE and its early, consistent and proper use. (bin-Reza et al., 2012).
However, the SARS (severe acute respiratory syndrome) was reduced in 8 of the 9 reviewed articles, even if the frequency of the infection with influenza is not homogeneous.
At least, as part of a series of strategies (gloves, frequent hand disinfection, special suits…) in order to reduce the infections caused by SARS.
I have made a super-effective homemade face mask
During the last weeks and due to the lack of medical protective equipment we have witnessed how some people have come up with their own respiratory protective devices.
Figure VI. Homemade protective masks.
In fact, we are even questioning the efficacy of face masks and respirators made with tested materials to filter micro-particles.
How is a homemade mask going to be able to prevent an infection?
Cloth face masks
Many of you have probably thought that:
“…I can wear a scarf or something similar to cover my mouth and nose…”
The truth is that apart from not protecting, since the material has a porosity that is superior to the diameter of any virus, it can also be harmful.
Figure VII. % of onset of clinical respiratory disease (CRI), influenza-like illness (ILI) and some viruses (Virus) in subjects who wore homemade cloth masks, control group and subjects with medical masks.
This is possibly due to the false feeling of safety they produce, which made people get closer to each other, taking less precautions. Not to mention how many times people touched these devices to adjust them to the face, increasing the risk of infection drastically.
In this study, the use of face masks reduced the ineffectiveness rate of the virus (confirmed by serology), in a 0.7% when compared to the control group. In other words, from 1000 exposures, 7 infections less, not so bad.
- Social distancing
- Wash your hands properly
- If you have a face mask, use it
What is better, a respirator or a medical mask?
Even though the answer may seem simple… It actually is not.
Smith et al. (2016) compared the studies that assessed the effects of medical masks and respirators (N95) about the infection degree of the sample.
In fact, they believe that even though respirators can be superior in laboratories and similar conditions, this is not so clear in the clinical environment, specially due to the discomfort of respirators.
Manipulation of respirators
These devices seal the face area that they cover while masks do not. Even doctors forget and they do not manipulate these devices properly, adjusting them with their hands and changing their position:
Figure IX. Effects of using a N95 respirator vs a medical mask and the risk of infection in laboratory, RCTs, cohort studies and controlled-case studies. The left area indicates the superiority of respirators, while the right supports the use of a medical mask.
Who should use them
This is due to the fact that not all studies show the same results. For example, in this case, the general use of N95 was superior to its punctual use (obviously). But the general use of medical masks also reduced the number of infections through droplets (both from bacteria and viruses, including influenza (flu)).
Figure X. RR of infection with bacteria, virus, flu and any other pathogen that can be transmitted through droplets after a general and punctual use of a respirator N95 and a face mask compared to not using these devices. Towards the left indicates the benefits of using them.
Apart from instructing how to use and manipulate them.
However, once again, Radonovich et al. (2019) published a RCT in JAMA about the good methodological quality of 2862 healthcare workers that shows that there were no significant differences between using a respirator N95 and a medical mask on the onset of infections with influenza. A 1% less in face mask users.
Still, let’s not forget that influenza is not like SARS-CoV-2, which is why the results are not completely extrapolated.
Figure XI. Tree diagrams that determines the RR of infection with influenza in laboratory (A) and others depending on the use of respirator (positive towards the left) or a medical mask (positive towards the right).
Should I use a mask?
In principle, no, but let me explain.
It does not mean that it is not effective. On the contrary, it means that you are not going to be as exposed as a doctor or any other healthcare professional.
You may have noticed that people are insisting that we should not use face masks against COVID-19.
This is due to the fact that there is a terrible lack of resources and our professionals are working with disposable masks for days. Consequently, this increases the risk of infection for them, even if these devices still do their function.
By no means I am not saying that you should not be afraid, but you should be responsible, stay up to date and be cautious when you go out.
But believe when I say that it is easier for you to maintain a distance of one meter and a half, than a doctor who is treating patients and being exposed to bio-aerosols just to diagnose them.
A professional that is exposed should use FFP3/N95 face masks when diagnosing patients. But they do not have the necessary tools, so they are running an unnecessary risk.
Figure XII. Infographics published by the Spanish Health Ministry in the last edition about the protection against occupational risks due to the COVID-19.
Figure XIII. Advice from the CDC.
- bin-Reza, F., Lopez Chavarrias, V., Nicoll, A., & Chamberland, M. E. (2012). The use of masks and respirators to prevent transmission of influenza: A systematic review of the scientific evidence. Influenza and Other Respiratory Viruses, 6(4), 257–267.
- Brown, C. K. (2019). Respiratory Protection Against Emerging Infectious Diseases: Face Masks, Respirators, and Tools for Choosing between Them. Health Security, 17(2), 133–139.
- Cascella M, Rajnik M, Cuomo A, et al. Features, Evaluation and Treatment Coronavirus (COVID-19) [Updated 2020 Mar 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.
- Centers for Disease Control and Prevention. (2020, 20 marzo). Coronavirus Disease 2019 (COVID-19) – Prevention & Treatment. Recuperado 25 marzo, 2020.
- Jefferson, T., Del Mar, C., Dooley, L., Ferroni, E., Al-Ansary, L. A., Bawazeer, G. A., … Rivetti, A. (2009). Physical interventions to interrupt or reduce the spread of respiratory viruses: Systematic review. BMJ (Online), 339(7724), 792.
- MacIntyre, C. R., Chughtai, A. A., Rahman, B., Peng, Y., Zhang, Y., Seale, H., … Wang, Q. (2017). The efficacy of medical masks and respirators against respiratory infection in healthcare workers. Influenza and Other Respiratory Viruses, 11(6), 511–517.
- MacIntyre, C. R., Seale, H., Dung, T. C., Hien, N. T., Nga, P. T., Chughtai, A. A., … Wang, Q. (2015). A cluster randomised trial of cloth masks compared with medical masks in healthcare workers. BMJ Open, 5(4), e006577.
- McCoy, C. E. (2017). Understanding the intention-to-treat principle in randomized controlled trials. Western Journal of Emergency Medicine, 18(6), 1075–1078.
- Radonovich, L. J., Simberkoff, M. S., Bessesen, M. T., Brown, A. C., Cummings, D. A. T., Gaydos, C. A., … Perl, T. M. (2019). N95 respirators vs medical masks for preventing influenza among health care personnel: A randomized clinical trial. JAMA – Journal of the American Medical Association, 322(9), 824–833.
- Smith, J. D., MacDougall, C. C., Johnstone, J., Copes, R. A., Schwartz, B., & Garber, G. E. (2016). Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: A systematic review and meta-analysis. Cmaj, 188(8), 567–574.
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