Recently, news media have been reporting that the much-respected Cochrane Collaboration has concluded that “masks don’t work.” To understand what the Cochrane study actually concluded, I’m going to take a brief detour into handwashing. Then, it’s back to Cochrane and masks.

Does handwashing work?

Does any solid evidence support the idea that thoroughly washing your hands with soap and water reduces the concentration of disease-causing germs (pathogens) on your hands? Yes, there is a large body of evidence, and it has been accumulating for many years.

In a typical study, people touch a dish specialized for bacterial growth (Petrie dish) with their fingers before and after washing their hands. After the Petrie dishes are incubated, a dense cluster of bacterial colonies form an outline of the fingers of the unwashed hand, but not the washed hand. Somewhere in the world, a microbiology student is probably repeating this experiment as you read this article, with the same results. For all practical purposes, it’s definite – incontrovertible. Proper hand washing reduces the pathogen concentration on your hands. You can take that to the bank.

Do handwashing regulations work?

When hospitals, clinics, nursing homes, rehabilitation centers, and food service facilities establish hand washing regulations, do they work? Sometimes they do, and sometimes they don’t. It depends on a key factor: cooperation with the regulations. In healthcare research, this sort of cooperation is called compliance.

An obvious example is found in the hospital. In the operating room, compliance with hand washing regulations is 100 percent or close to it. The surgeons and O.R. nurses diligently scrub. They undoubtedly watch each other to make sure that everyone is doing likewise. In the rest of the hospital, several studies indicate that compliance is nowhere near 100 percent.

Do masks work?

To stop the spread of a contagious respiratory virus, a mask must capture respiratory droplets and smaller particles called aerosols. Particles of this size are exhaled into the air by an infected person, creating a contagious situation. So, does any solid evidence support the idea that mask material captures a significant percentage of droplets and aerosol particles?

Yes, there have been a number of studies concluding exactly that. N-95 masks do a better job than surgical masks, but they both capture significant amounts of droplets and aerosols. There is very little doubt about that. You can take it to the bank. However, the Cochrane study was not about that.

Do mask mandates work?

The Cochrane mask study combined data from several epidemiological studies on the effect of mask mandates and guidelines on the spread of several respiratory infections, including influenza and COVID-19. They found no evidence that these mandates and guidelines had any measurable effect on the spread of respiratory disease.

So, if masks work, why didn’t the mask mandates seem to stop the spread of disease? In the “plain-language summary” towards the beginning of their paper, the authors identify the likely culprit in one sentence:

“Relatively low numbers of people followed the guidance about wearing masks or about hand hygiene, which may have affected the results of the studies.”

In other words, there was poor compliance. During the height of the pandemic, I observed multiple instances of the following:

  • Some people were wearing masks on their chins.

  • Some people were wearing masks under their nose.

  • Some people were wearing masks so loosely fitting that air escaped from the sides with each breath.

  • Some people were wearing masks when silent, removing them when speaking.

  • Some people were refusing to wear masks at all.

Undoubtedly, most of you reading this article observed these same behaviors.

It’s not just about pandemics

The issue of compliance is not just about controlling pandemics. It is one of the most important issues in health care. Almost every health care intervention requires compliance to work. This applies to medicinal drugs, therapeutic exercise, dietary advice, chiropractic adjustments, smoking cessation – you name it. Here are some common-sense rules about compliance for any health care intervention:

  1. If you don’t do it, it won’t work.

  2. If you don’t do it properly, it probably won’t work properly.

  3. If you stop doing it prematurely, it will probably stop working prematurely.

  4. If you do it properly for a reasonable period of time, and the results are still not good, consider a different intervention.

Sources For This Article

Jefferson T, Dooley L, Ferroni E, Al-Ansary LA, van Driel ML, Bawazeer GA, Jones MA, Homann TC, Clark J, Beller EM, Glasziou PP, Conly JM. Physical Interventions to Interrupt of Reduce the Spread of Respiratory Viruses. Cochrane Database of Systematic Reviews 2023, Issue 1. Art. No.: CD006207. DOI: (The Cochrane Collaboration Mask Study)

Hamilton Health Sciences. The Power of Proper Hand Washing; November 23, 2018: (Includes photos of petri dish results before and after hand washing).

Asadi S, Cappa CD, Barreda S, Wexler AS, Bouvier NM, Ristenpart WD. Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities. Scientific Reports, 2020; 10: 15665. (Ability of masks to block exhaled respiratory particles)

Sands M, Aunger R. Determinants of hand hygiene compliance among nurses in US hospitals: A formative research study. PLoS ONE 15(4): e0230573. pone.0230573 (Compliance with hand washing in health care settings)

About the Author

While serving as a medical specialist (MOS 91-B) in the U.S. Army Reserve, Dr. Masarsky earned his Doctor of Chiropractic degree from New York Chiropractic College in 1981. He is in the private practice of chiropractic in the Virginia suburbs of Washington DC with his wife and partner, Dr. Marion Todres-Masarsky. For research citations related to this article or appointment information, contact Dr. Masarsky at 703-938-6441 or Also visit his practice’s website:, and You Tube channel:

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