Melanie Grasso: Read for yourself: face masks don't stop a flu virus

To The Daily Sun:

RE: “No significant effect of face masks on transmission of laboratory-confirmed influenza:”

Some questions have been asked recently, to provide more detail on the effectiveness of face masks, and why masks have been used traditionally in health care settings. The below article will answer some of those questions.

I will quote a few paragraphs from the CDC's website, the article: Emerging Infections Diseases, Volume 26, Number 5—May 2020, “Nonpharmaceutical Measures for Pandemic Influenza in Nonhealthcare Settings-Personal Protective and Environmental Measures”

The full article: (https://bit.ly/3113IPx)

From the abstract: “Here, we review the evidence base on the effectiveness of nonpharmaceutical personal protective measures and environmental hygiene measures in non-health care settings and discuss their potential inclusion in pandemic plans. Although mechanistic studies support the potential effect of hand hygiene or face masks, evidence from 14 randomized controlled trials of these measures did not support a substantial effect on transmission of laboratory-confirmed influenza.”

From the article: “We searched four databases (Medline, PubMed, EMBASE, and CENTRAL) for literature in all languages. We aimed to identify randomized controlled trials (RCTs) of each measure for laboratory-confirmed influenza outcomes for each of the measures because RCTs provide the highest quality of evidence."

"The effect of hand hygiene combined with face masks on laboratory-confirmed influenza was not statistically significant (RR 0.91, 95% CI 0.73–1.13; I2 = 35%, p = 0.39)."

"A pooled analysis of two studies in university residential halls reported a marginally significant protective effect of a combination of hand hygiene plus face masks worn by all residents (RR 0.48, 95 percent CI 0.21–1.08; I2 = 0 percent, p = 0.08) (Appendix Figure 6) (9,10).

"In our systematic review, we identified 10 RCTs that reported estimates of the effectiveness of face masks in reducing laboratory-confirmed influenza virus infections in the community from literature published during 1946–July 27, 2018."

"In pooled analysis, we found no significant reduction in influenza transmission with the use of face masks (RR 0.78, 95 percent CI 0.51–1.20; I2 = 30 percent, p = 0.25) (Figure 2). One study evaluated the use of masks among pilgrims from Australia during the Hajj pilgrimage and reported no major difference in the risk for laboratory-confirmed influenza virus infection in the control or mask group (33). Two studies in university settings assessed the effectiveness of face masks for primary protection by monitoring the incidence of laboratory-confirmed influenza among student hall residents for five months (9,10). The overall reduction in ILI or laboratory-confirmed influenza cases in the face mask group was not significant in either studies (9,10)."

"Disposable medical masks (also known as surgical masks) are loose-fitting devices that were designed to be worn by medical personnel to protect accidental contamination of patient wounds, and to protect the wearer against splashes or sprays of bodily fluids (36). There is limited evidence for their effectiveness in preventing influenza virus transmission either when worn by the infected person for source control or when worn by uninfected persons to reduce exposure. Our systematic review found no significant effect of face masks on transmission of laboratory-confirmed influenza.”

Melanie Grasso

Laconia