Masks Make People and Communities Safer: The CDC Update Their Guidance
As COVID-19 cases and hospitalizations soar across the country, the Centers for Disease Control and Prevention have reminded us that masks and distancing decrease the spread of COVID-19. This should not be news to anyone. However, disinformation and COVID-fatigue have allowed some communities and people to ignore this simple fact. On November 10, 2020, the Centers for Disease Control and Prevention summarized data from laboratory and epidemiological studies, which strengthen the scientific understanding of how masks protect the wearer and others and how mask mandates and distancing decrease the transmission of COVID-19.
Wear a mask to Protect YOURSELF AND THOSE Around You
The CDC cited data which confirmed that masks protect both the wearer of the mask and those around an infected wearer. Ueki et al. used models of human faces to simulate an infected and an uninfected person. They varied the distance between the models and who was wearing the mask. When both the infected and uninfected model were wearing a mask, the viral load was decreased by up to 71% and the titer by up to 76%, compared to no masks. The further the models were apart, the less transmission. However, even if the infected model was not wearing the mask, the uninfected model still had lower viral levels. Ueki et al. Effectiveness of face masks in preventing airborne transmission of SARS-CoV-2. Ueki et al. mSphere (October 21, 2020).
Mask ordinances decrease the spread of COVID-19
An epidemiological study conducted by E. Sacham et al in counties around St. Louis, MO, showed that counties with mask mandates had significantly lower rates of new COVID-19 cases (average daily percent growth) compared to counties without mask mandates. While this was released “pre-print” and not peer-reviewed yet, it contributes to the “real-world” evidence that mask ordinances slow the spread of COVID-19, even in a state being hit hard in the pandemic. Shacham et al. (October 2020) Association of county-wide mask ordinances with reductions in daily COVID-19 incident case growth in a Midwestern region over 12 weeks.. MedRxiv. https://www.medrxiv.org/content/10.1101/2020.10.28.20221705v1
Mask wearing could save the country $1 trillion dollars
The CDC is also citing economic reasons for universal mask wearing. Citing 2 articles, the CDC estimates that universal mask-wearing could decrease transmission, avoid future lockdowns and save up to $1 trillion dollars in economic loss. CDC. (November 2020) Scientific Brief: Community Use of Cloth Masks to Control the Spread of SARS-CoV-2 https://www.cdc.gov/coronavirus/2019-ncov/more/masking-science-sars-cov2.html
Not all masks are created equal
The Centers for Disease Control and Prevention recommends cloth masks with at least 2 layers and no valves. Surgical masks are likely more effective. They are needed by healthcare workers, but are more available than N95 masks. I will discuss mask selection further in a future update. CDC (November 2020) COVID-19 Science Update https://www.cdc.gov/library/covid19/111020_covidupdate.html
The Centers for Disease Control and Prevention have strengthened their recommendations to encourage universal mask-wearing and to encourage governments to enact mask mandates. Whether people or communities are motivated by keeping themselves safe, keeping others safe or simple economic benefits; we can all find a reason to wear a mask.
Of note, the CDC website has not updated all of its messaging yet. They still have infographics and headers on the website stressing that masks protect others. They need to update their messaging to make sure everyone is up to date on the importance of mask-wearing for themselves and others.
Stay safe. Be well. Get a flu shot. Wear a mask.
