Masks are most likely to reduce the spread of COVID-19. The CDC recommends that people wear masks in public settings and when around people who do not live in your household. Masks should not be worn by children under the age of 2 or anyone who has trouble breathing, is unconscious, incapacitated, or unable to remove the masks without assistance. 

References:

1.https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks

2.https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover-guidance.html