Our @CDCDirector proposes the US should diverge from the rest of the world & @WHO guidelines & have children wear masks outdoors while playing contact sports like soccer.
Available scientific evidence indicates this will not help control the pandemic, but will be harmful. See
https://twitter.com/NewDay/status/1389923232246124544
Available scientific evidence indicates this will not help control the pandemic, but will be harmful. See

1. Study of >91,000 *youth soccer* players over last summer and only ONE transmission event suspected, lead author says not known if transmission was indoors or outdoors or actually from home. https://www.medrxiv.org/content/10.1101/2020.09.25.20201616v1.full.pdf
2. Univ of Wis study looking at >30,000 high school athletes w/2390 COVID cases; 5 from school, 1 from sports. Sport mask use *not correlated* w/incidence (of course as only 1 case of covid spread during sports!). https://www.medrxiv.org/content/10.1101/2021.02.18.21251986v1
3. Hubei province study of 1245 infected individuals, only *one* infected outdoors, no youth outdoor transmission. https://onlinelibrary.wiley.com/doi/10.1111/ina.12766
4. In our Wood CO WI study of K-12 schools with minimal transmission in high community prevalence over 13 weeks, recess was held outdoors without masks and no transmission events traced to recess. https://www.medrxiv.org/content/10.1101/2021.03.16.21253761v1
5. Of all adult rugby players found to have been infected with SARS-CoV-2 during the time of their matches, not a single one transmitted to another player in spite of this being a high contact sport. https://bjsm.bmj.com/content/early/2021/02/10/bjsports-2020-103714
6. Two studies here showing the effect of masking according to exercise intensity: VO2 max decreases, CO2 increases, shortness of breath increases https://bjsm.bmj.com/content/early/2021/03/05/bjsports-2020-103758
https://pubmed.ncbi.nlm.nih.gov/32969531/#affiliation-1
https://pubmed.ncbi.nlm.nih.gov/32969531/#affiliation-1
7. "Being consistently inactive was a stronger risk factor for severe COVID-19 outcomes than any of the underlying medical conditions and risk factors identified by CDC except for age and a history of organ transplant"(masking kids discourages exercise)
8. The WHO advises against mask usage for children and adults alike during intense exercise. https://www.who.int/publications/i/item/advice-on-the-use-of-masks-in-the-community-during-home-care-and-in-healthcare-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak/
9. Even California has not had kids mask outdoors during sports competition. If our children are asked to mask outdoors during exercise, they will be pulled from competition. I am not a "right wing lunatic". I am a scientist and human who cares about the well-being of children.