Wearing face masks helps reduce the spread of COVID-19, but it only confers partial protection and should be combined with additional public health measures

Key takeaway

A growing body of scientific evidence supports the use of face masks to reduce the transmission of viral respiratory infections like COVID-19. However, face masks only confer partial protection and should be combined with other public health measures, such as physical distancing and proper hand hygiene. Due to the use of a wide variety of face masks, more research is needed to assess the efficacy of different types of masks and mask material in various community settings, such as public spaces, schools, or workplaces.

Reviewed content

Verdict:

Inaccurate

Claim:

“Mask mandates do nothing to stop [the spread of] COVID[-19]”; There is “overwhelming scientific evidence” that masks do not work

Verdict detail

Inaccurate: Scientific evidence indicates that wearing face masks effectively reduces the spread of COVID-19 by blocking viral transmission through respiratory droplets and some aerosol particles. However, wearing face masks only confers partial protection and should be combined with other public health measures, like physical distancing and good hand hygiene.
Misrepresents sources: The studies cited acknowledge that wearing face masks confers some degree of protection against COVID-19 or are inconclusive, but do not directly support the claim that face masks do not work.
Misrepresents a complex reality: Graphs correlating face masks mandates and COVID-19 infection rates in different countries do not take into account other factors that influence the course of the pandemic, such as additional public health measures or a country’s demographics.

See our method of evaluation

Full Claim

“Mask mandates do nothing to stop [the spread of] COVID[-19]”; “The narrative simply assumes rather than proves that masks work, despite overwhelming scientific evidence to the contrary”; “The plentiful evidence we have indicates masks would not meaningfully help with aerosol transmission”; “No matter how strictly mask laws are enforced nor the level of mask compliance the population follows, cases all fall and rise around the same time.”

An article published by The Federalist on 29 October 2020 claims that face masks are ineffective at reducing the spread of COVID-19. In support of its claim, the article cites several scientific studies and shows 12 graphs comparing COVID-19 cases per million people in European countries and U.S. states that required the use of face masks in public spaces with those that did not. This review examines whether scientific evidence and the data provided in the article support the claim.

Claim 1 (Inaccurate): “The narrative simply assumes rather than proves that masks work, despite overwhelming scientific evidence to the contrary.”

The Federalist article misrepresents the conclusions of several scientific sources cited. First, the article cites a July 2020 viewpoint by two epidemiologists from the Centre for Evidence-Based Medicine at Oxford University. In the viewpoint, the authors discuss the current state of clinical research on face masks efficacy, but do not make any conclusions regarding the efficacy of face masks in reducing the spread of COVID-19. Instead, the authors emphasize the importance of clinical evidence to guide public health decisions and highlight uncertainties regarding the efficacy of face masks, as there has been a lack of robust clinical trials on the subject.

The authors mention that systematic reviews of clinical trials conducted before the pandemic showed no significant effect of wearing face masks in reducing the spread of influenza or influenza-like illness. However, The Federalist article fails to mention that there were only a few studies analyzed that differed in their methodology, reducing the ability to draw clear conclusions, as the authors noted:

“The design of these twelve trials differed: viral circulation was usually variable; none had been conducted during a pandemic. Outcomes were defined and reported in seven different ways, making comparison difficult. It is debatable whether any of these results could be applied to the transmission of SARs-CoV-2.”

Another misrepresented source is an April 2020 Perspective article published in the New England Journal of Medicine by Klompas et al.^[1]. The Federalist article quotes the statement that “wearing a mask outside health care facilities offers little, if any, protection from infection.” However, in July 2020 the authors published a follow-up letter warning that some people were wrongly citing their article “as support for discrediting widespread masking.” The authors explained that this statement applied to “passing encounters in public spaces, not sustained interactions within closed environments.”

“In truth, the intent of our article was to push for more masking, not less. It is apparent that many people with SARS-CoV-2 infection are asymptomatic or presymptomatic yet highly contagious, and that these people account for a substantial fraction of all transmissions. Universal masking helps to prevent such people from spreading virus-laden secretions, whether they recognize that they are infected or not.”

The Federalist article also cites several research studies, including a 2009 clinical trial published in the American Journal of Infection Control and a 2011 systematic review published in Influenza and Other Respiratory Viruses^[2,3]. However, neither of these studies concluded that face masks are not useful for curbing the spread of respiratory diseases. Instead, both studies highlighted that data on face masks research is limited and pointed out the need for more robust clinical trials.

The other two studies that The Federalist article cites are a 2010 systematic review and a 2017 analysis of previous clinical trials that support the use of face masks for reducing the spread of respiratory infections, contrary to what the article claims^[4,5]:

“There is some evidence to support the wearing of masks or respirators during illness to protect others, and public health emphasis on mask wearing during illness may help to reduce influenza virus transmission. There are fewer data to support the use of masks or respirators to prevent becoming infected.” — Cowling et al., (2010) Epidemiology and Infection

“We found evidence to support universal medical mask use in hospital settings as part of infection control measures to reduce the risk of [clinical respiratory illness] and [influenza-like illness] among [healthcare workers]. […] Our analysis confirms the effectiveness of medical masks and respirators against SARS.” — Offeddu et al., (2017) Clinical Infectious Diseases

Consistent with these studies, growing scientific evidence suggests that wearing even simple cloth face coverings can reduce the transmission of viral respiratory infections like COVID-19. As Health Feedback explained in this previous review, several recent studies support the use of face masks as part of a protection strategy against COVID-19 in healthcare and community settings^[6-9].

However, no face mask is completely effective at blocking viral transmission. For example, infection can also occur if someone touches their eyes or mouth after their hands were contaminated with infectious droplets or aerosols. For this reason, health authorities recommend that people practice physical distancing and proper hand hygiene, which act as additional layers of protection to reduce the spread of COVID-19. More research is also needed to assess the efficacy of wearing different types of masks in various settings, such as indoor versus outdoor environments.

Claim 2 (Misleading): “The plentiful evidence we have indicates [that] masks would not meaningfully help with aerosol transmission”

Transmission of the virus that causes COVID-19 occurs through respiratory droplets and aerosols in the air. As Health Feedback explained in this previous review, people infected with COVID-19 can release viral particles of different sizes when they cough, sneeze, sing, talk, or breathe. Respiratory droplets, which are considered a main mode of COVID-19 transmission, are larger than five micrometers and tend to rapidly fall to the ground. However, increasing evidence suggests that aerosol transmission may also play a role in the spread of COVID-19. Aerosols are particles smaller than five micrometers that can remain in the air for a longer time and travel further distances than respiratory droplets. Aerosols can be directly released by an infected person, but can also form by evaporation of respiratory droplets in smaller particles.

Several studies suggest that face mask use can block aerosols to some degree. An April 2020 study published in Nature Medicine found that surgical masks reduced the amount of various respiratory viruses, including seasonal coronaviruses, in droplets and aerosols released from infected individuals^[10]. An August 2020 study found that face masks made at home of different cloth materials could efficiently filtrate aerosol particles of a range of sizes. An adequate number of layers and a proper fit were crucial to minimize leak flows^[11]. These studies support the use of face masks to reduce viral transmission in the form of respiratory droplets as well as aerosols.

Claim 3 (Misrepresents a complex reality): “No matter how strictly mask laws are enforced nor the level of mask compliance the population follows, cases all fall and rise around the same time.”

The Federalist article shows 12 graphs displaying the number of COVID-19 cases per million people in several European countries and U.S. states over time to support their claim that face mask use does not impact the spread of COVID-19. The article then compares the rate of COVID-19 infection in European countries or U.S. states that mandated the use of face masks and those that did not.

This comparison is misleading because it does not take into account when each country implemented the use of face masks, nor potential confounding effects, such as additional public health measures or population demographics. Furthermore, the article cherry-picks certain countries to make the comparison, excluding countries that adopted face masks early but had low death rates, like South Korea or Japan. As examples of regions that did not mandate face masks, the article only includes Nordic countries and the state of Georgia, which are not necessarily representative.

This comparison assumes that face masks are the only measure being implemented to reduce the spread of COVID-19 and fails to consider other potential public health measures that states or countries can also take, including lockdowns, physical distancing, increased testing and contact tracing for the isolation of possible COVID-19 positives. Cold weather could also favor the spread of COVID-19 by providing conditions that prolong virus survival and drive people to spend more time in less ventilated, indoor spaces. The reopening of schools and universities may also increase interactions between people from different households, potentially contributing to the recent rise in COVID-19 cases.

In addition, the article does not acknowledge populational differences or social policies in different countries. Many factors besides the use of face masks influence the course of the pandemic, including population demographics, healthcare systems, or the overall health status of the population, as Health Feedback mentioned in this review. Therefore, country-wide statistics are generally misleading, as the pandemic played out very differently in different regions, as shown by the comparison between Sweden and New York.

Sweden and New York differ drastically in their demographics. Sweden has a much lower population density, with around half of Swedes living in single-person households. In contrast to New York, and the U.S. more broadly, Sweden has universal healthcare coverage and lower levels of health inequality. Finally, Sweden has been wrongly used as an example of a country with no restrictions during the COVID-19 outbreak. Although a lockdown and face mask use were not mandated, many Swedes voluntarily adhered to government recommendations to reduce the spread of COVID-19, including physical distancing and staying home.

To account for the differences in the types of public health measures implemented in different countries and accurately quantify the impact of a given intervention on disease transmission, researchers use mathematical models. An October 2020 study published in the International Journal of Infectious Diseases used one of these models to quantify the effects of wearing non-medical face masks, shelter-in-place policies, and case isolation in reducing the spread of COVID-19^[12]. The authors estimated that non-medical mask-wearing by 75% of the population reduced infections, hospitalizations, and deaths by 37.7%, 44.2%, and 47.2%, respectively. Another recent study found that countries that adopted face mask use shortly after the COVID-19 outbreak started, like South Korea or Japan, tended to maintain lower death rates and had shorter outbreaks than countries that did not^[13]. However, none of these countries are included in The Federalist article.

Claim 4 (Lacks context): “The U.S. surgeon general and the Centers for Disease Control both previously said that ‘masks are NOT effective in preventing [the] general public from catching coronavirus’”

As Health Feedback explained in this previous review, public health authorities initially discouraged the public from wearing face masks due to concerns over a shortage of protective equipment, like surgical and N95 masks, for healthcare workers at the frontlines of the COVID-19 pandemic response. This message is evident in this 29 February 2020 tweet by U.S. Surgeon-General Jerome Adams, who urged people to stop buying masks to ensure that healthcare workers had a sufficient supply.

However, scientific evidence later emerged showing that infected people without symptoms can still transmit the virus that causes COVID-19. This development prompted the World Health Organization and the U.S. Centers for Disease Control and Prevention to recommend that the public use cloth face masks in shared spaces to reduce the spread of COVID-19.

In summary, The Federalist article misrepresents the conclusions of several scientific studies and uses graphs in a misleading way to claim that face masks cannot reduce the spread of COVID-19. Public health agencies recommend that the general public use face masks to reduce the spread of COVID-19 because masks act as physical barriers that block the release of respiratory droplets into the air and reduce the spread of aerosol particles. However, more research is needed to assess which types of masks are more efficient in different community settings.

READ MORE

This article from Nature explains why data supports the use of face masks by the general public for reducing the spread of COVID-19.

REFERENCES

• 1 – Klompas et al. (2020) Universal Masking in Hospitals in the Covid-19 Era. New England Journal of Medicine.
• 2 – Jacobs et al. (2009) Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: A randomized controlled trial. American Journal of Infection Control.
• 3 – Reza et al. (2011) The use of masks and respirators to prevent transmission of influenza: a systematic review of the scientific evidence. Influenza and Other Respiratory Viruses.
• 4 – Cowling et al. (2010) Face masks to prevent transmission of influenza virus: a systematic review. Epidemiology and Infection.
• 5 – Offeddu et al. (2017) Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis. Clinical of Infectious Diseases.
• 6 – Wang et al. (2020) Reduction of secondary transmission of SARS-CoV-2 in households by face mask use, disinfection and social distancing: a cohort study in Beijing, China. BMJ Global Health.
• 7 – McIntyre and Chughtai. (2020) A rapid systematic review of the efficacy of face masks and respirators against coronaviruses and other respiratory transmissible viruses for the community, healthcare workers and sick patients. International Journal of Nursing Studies.
• 8 – Chu et al. (2020) Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. The Lancet.
• 9 – Wang et al. (2020) Association Between Universal Masking in a Health Care System and SARS-CoV-2 Positivity Among Health Care Workers. Journal of American Medical Association.
• 10 – Leung et al. (2020) Respiratory virus shedding in exhaled breath and efficacy of face masks. Nature Medicine.
• 11 – Drewnick et al. (2020) Aerosol filtration efficiency of household materials for homemade face masks: Influence of material properties, particle size, particle electrical charge, face velocity, and leaks. Aerosol Science and Technology.
• 12 – Zhang et al. (2020) The impact of mask-wearing and shelter-in-place on COVID-19 outbreaks in the United States. International Journal of Infectious Diseases.
• 13 – Leffler et al. (2020) Association of Country-wide Coronavirus Mortality with Demographics, Testing, Lockdowns, and Public Wearing of Masks. American Journal of Tropical Medicine and Hygiene.