What do the new CDC mask guidelines really mean?


A: The take-home message is that mitigation works. What we have learned from four influenza pandemics, HIV, and SARS pandemics in the last 100 years is that taking steps to protect ourselves and others works.

The CDC guidelines released earlier suggest that vaccinated people in virus hotspots across the country should wear masks indoors. This includes children, teachers, and staff in K-12 schools. This is a departure from earlier recommendations that allowed vaccinated individuals to resume activities resembling pre-pandemic days.

The emergence of the Delta variant and those that are to come changes everything. People are known to shed 1,000x more of the Delta variant than pervious forms of the virus. And it mutates faster. Those vaccinated who have breakthrough infections can spread the Delta variant even if symptoms and illness are not life-threatening or severe. This is why vaccinated people need to wear a mask indoors.

The old tropes of freedom, misinformation, and fear mongering have surfaced as expected. However, there are good questions that have emerged. What is a COVID-19 hotspot*? Why do we need to wear a mask if we are fully vaccinated and have done all that we’ve been asked to do? Isn’t this a problem of the unvaccinated?

Wearing a mask is one part of a practice of hygiene that has helped the world emerge from pandemics in the past until vaccines could be developed and administered. During the four influenza pandemics of the last 100 years, the world was able to significantly decrease deaths by practicing mitigation long before vaccines were fully developed. Almost 3% of the world’s population died from the 1918 flu. By the 2009 flu pandemic, 0.001 to 0.007% of the world’s population died. This is due to the careful development of vaccines over time. But quarantine, mask wearing, and proper hygiene keep transmission of disease at a minimum until vaccines can be developed and administered. These practices are known to help even when effective vaccines are refused.

We are up against a unique time in history. Though this is a coronavirus, not an influenza virus, prevention measures do not change. So if you are vaccinated and in a hotspot where the Delta variant is prominent, wear your mask, keep social-distancing, and wash your hands. Mitigation saves lives.

Interim public health recommendations

How to protect yourself and others

*What is a “hotspot” region? Note: this definition of hotspot does not account for outbreaks in small communities.

“[U.S.] Counties defined as hotspot counties met all four of the following criteria, relative to the date assessed: 1) >100 new COVID-19 cases in the most recent 7 days, 2) an increase in the most recent 7-day COVID-19 incidence over the preceding 7-day incidence, 3) a decrease of <60% or an increase in the most recent 3-day COVID-19 incidence over the preceding 3-day incidence, and 4) the ratio of 7-day incidence/30-day incidence exceeds 0.31. In addition, hotspots must have met at least one of the following criteria: 1) >60% change in the most recent 3-day COVID-19 incidence, or 2) >60% change in the most recent 7-day incidence.” From here. 

History of pandemics in the last 100 years:




Viral infection and transmission of Delta variant

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