VERA FILES FACT CHECK: Isko Moreno inaccurately cites US ‘CDC’ study on low effectiveness of face shields

Manila Mayor Francisco “Isko Moreno” Domagoso wrongly attributed to the United States (U.S.) Centers for Disease Control and Prevention (CDC) a study that suggested limited effectiveness of face shields in curbing the transmission of the coronavirus disease 2019 (COVID-19).

He also left out relevant context when he cited the study’s findings in bolstering his call on local health experts to review the government’s mandatory face shield policy.


In a June 4 interview on CNN Philippines’ The Source, Moreno cited a study of the “Association for Professionals in Infectious Control and Epidemiology on the CDC website,” saying:

“There is a recent study … ito (this is) CDC ah. Health institute, kinomisyon ng (commissioned by the) CDC. Sinabi sa conclusion nila ha (The conclusion [of the study said]), ‘surgical mask[s] alone provided protection, surpassing the protection provided by face shields alone. Both used together provided the best protection,’ tama naman (that’s correct). ‘Although combined protection was similar to surgical mask use alone,’ ibig sabihin (that means) [wearing a] mask is enough. As long as you wear it properly and you wear it all the time.”

Moreno added:

“So, kung ‘yun ‘yung tama, CDC ‘yun ‘no — I think it’s a good reference, ‘no. Kung ‘yun ‘yung tama, then ‘yun bang pagre-require natin against sa hirap ng buhay ng tao eh sapat ba? ‘Yun ‘yung akin….”

(So if that is the correct [guidance], that’s the CDC, right — I think it’s a good reference, right. If that’s the correct guidance, then [our policy] requiring [the public to use face shields, when put] against the added burden on the lives of the people, is it enough? That’s what I’m saying.)

Source: CNN Philippines, Manila Mayor Isko Moreno | The Source, June 4, 2021, watch from 4:00 to 4:51

The Manila mayor said he was “just borrowing a study of a country of good reference.” He earlier made the headlines after calling on the government to “rethink” and “adjust” its policy requiring the general public to use face shields on top of face masks.


The study cited by Moreno, which was published in January at the American Journal of Infection Control (the official publication of Association for Professionals in Infection Control and Epidemiology), was not “commissioned” by the CDC, as confirmed by infectious disease professor Teena Chopra, one of the researchers, in an email to VERA Files Fact Check.

The CDC has not issued an official recommendation for or against the use of face shields together with masks by the general public to prevent COVID-19 spread.


The agency, however, “does not recommend” the use of face shields — primarily meant to protect one’s eyes — alone, according to its guidelines on mask wearing last updated in April.

If a person “must wear a face shield instead of a mask,” the CDC said the device should wrap around the side of the wearer’s face and extend below one’s chin, or be hooded. It said “limited available data … suggest” that these types work “better” at preventing spray of respiratory droplets, which is among the modes of transmission of the COVID-19 virus.

In its list of considerations for non-U.S. healthcare workers, the CDC said, should there be a shortage of medical masks, wearing face shields alone or together with cloth masks may serve as a “potential alternative” and “last resort.”

However, the agency said it is “important” to consider the “limited ability of face shields to fully protect against droplets and the lack of evidence on effectiveness of non-medical fabric masks against respiratory viruses.”

There is currently “limited guidance for when or if the public should wear both face masks and face shields,” according to a global team of public health experts convened by international nonprofit Meedan in a recently updated explainer on its online health desk.

Limitations of the study

While the January study did bear out the findings that Moreno cited in the CNN Philippines interview, the mayor left out some important context.

The study made use of a simulation — meaning there were “no actual humans” included in the experiment — and was performed “under controlled conditions.” Hence, the researchers said its “obvious limitations need to be highlighted to help interpretation and guide future studies.”

Since it was a simulation, the results “probably represented best case experiments,” they said, adding that although simulated speech is “able to give valuable information” on aerosol spread and face mask or shield protection, it could not “capture” variations in speech and breathing patterns, volume, and head size, among others.

The experiment also tested the spread of nebulized bacteria rather than the SARS-CoV-2 virus, which causes COVID-19, due to “safety requirements.” It was also not able to simulate “various droplet sizes.”

Only one mask type (surgical) was used in the experiment, which may be a “limitation” because “cloth masks are so widely used in the general population,” the authors said. But since they “vary widely,” cloth masks “could not be represented in a single experiment,” they added.

In the Philippines, the Department of Health (DOH) allows the general public to use either surgical face masks or cloth masks, noting that surgical masks may only be used once, while the latter may be reused after a proper wash.

The authors of the study noted some advantages of wearing face shields, such as possibly providing added eye protection for high-risk workers and prolonging mask life by protecting its surface from contamination. But ultimately, they said it was “difficult to tell, based on this simple simulation, whether the protection afforded by a surgical mask combined with a face shield is improved.”

PH not sole country to require face shields

In the CNN Philippines interview, Moreno said the Philippines “may be the only [country]” in the world to have required the general public to use face shields on top of face masks. This is not the case.

Aside from the Philippines, Peru also requires its people to wear face shields to supplement mask wearing in spaces at “risk of crowding,” including vaccination centers, shopping centers, markets, and department stores, as reported by state-run Peruvian news agency Andina. The same directive applies to outbound travellers in the airport and during the flight.

In a June 4 statement, Health Undersecretary Maria Rosario Singh-Vergeire, concurrent spokesperson, said the country “cannot afford to relax its policies on personal preventive measures,” saying that face shields “provide another layer of protection.”

On June 16, however, Health Undersecretary Leopoldo Vega said in a media briefing that face shields may be removed “especially by those who are simply walking or working outdoors (e.g. construction workers, vendors, couriers)” since the risk of transmission is “very low.” But he maintained that face shields must still be donned together with face masks inside establishments, especially during close contact interactions.

The next day, Health Secretary Francisco Duque III, in a message to The Manila Times, said the country’s COVID-19 Inter-Agency Task Force will be discussing the face shields policy after Senate President Vicente “Tito” Sotto III tweeted that same morning that President Rodrigo Duterte had “agreed” to require the use of face shields only in hospitals.

Defending the government policy, Palace Spokesperson Harry Roque earlier falsely equated the protection one gets from face coverings (mask and shield) to that of getting vaccinated. (See VERA FILES FACT CHECK: Roque wrongly equates protection from face mask and shield to getting COVID-19 vaccine)


Inter-Agency Task Force for the Management of Emerging Infectious Diseases, OMNIBUS GUIDELINES ON THE IMPLEMENTATION OF COMMUNITY QUARANTINE IN THE PHILIPPINES with Amendments as of December 14, 2020, Dec. 14, 2020

CNN Philippines, Manila Mayor Isko Moreno | The Source, June 4, 2021

CNN Philippines, Isko Moreno urges gov't to scrap face shield policy, June 2, 2021

Rappler, Isko Moreno urges gov't to drop ‘face shield’ policy, June 2, 2021

GMA Network, Isko urges gov't stop requiring Filipinos to wear face shields vs. COVID-19, June 2, 2021

Isko Moreno Domagoso Official Facebook Page, Ang face shield ay dapat nang itigil…, June 2, 2021

American Journal of Infection Control, A laboratory model demonstrating the protective effects of surgical masks, face shields, and a combination of both in a speaking simulation, Jan. 20, 2021

American Journal of Infection Control, Aims and Scope, Accessed June 15, 2021

Wayne State University, School of Medicine (Infectious Diseases): Teena Chopra, Accessed June 14, 2021

Crossmark, Authors: A laboratory model demonstrating the protective effects of surgical masks, face shields, and a combination of both in a speaking simulation, Accessed June 15, 2021

U.S. Centers for Disease Control and Prevention, Guidance for Wearing Masks, Updated April 19, 2021

World Health Organization, Coronavirus disease (COVID-19): How is it transmitted?, Dec. 13, 2020

U.S. Centers for Disease Control and Prevention, SARS-CoV-2 Transmission, Updated May 7, 2021

U.S. Centers for Disease Control and Prevention, Emergency Considerations for PPE, Updated March 18, 2021

Meedan’s Health Desk, How effective is it to use only a face shield to protect from COVID-19?, Updated June 9, 2021

Meedan’s Health Desk, About (Mission), Accessed June 15, 2021

Lexico by and Oxford University Press, Nebulization: Definition, Accessed June 15, 2021

Department of Health Official Twitter Account, Ang BIDA, alam ang tamang paggamit ng face masks…, July 22, 2020

Andina, Peru: Use of face shields mandatory at markets, shopping centers, April 19, 2021

El Peruano (Peru Government Official Newspaper), Normas Legales, April 24, 2021

Ministerio de Salud del Peru Official Facebook Page (Ministry of Health Peru), ATTENTION LIMA AND CALLAO, June 2, 2021

Overseas Security Advisory Council (OSAC), Health Alert: Peru, COVID-Related Requirements for Arrivals Instituted January 4, Jan. 5, 2021


PTV Philippines Official Youtube Channel, PANOORIN: Public Briefing #LagingHandaPH | June 16, 2021, June 16, 2021

Red Mendoza (Health Reporter, The Manila Times), New: @DOHgovph @SecDuque tells…, June 17, 2021

Tito Sotto Official Twitter Account, Last night, the President…, June 17, 2021

(Guided by the code of principles of the International Fact-Checking Network at Poynter, VERA Files tracks the false claims, flip-flops, misleading statements of public officials and figures, and debunks them with factual evidence. Find out more about this initiative and our methodology.)


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