The World Health Organization has released its guidance on face masks for children, as students— in some parts of the country at least— return to their classrooms to start the new school year. Children age 5 and younger shouldn’t be required to wear masks, the WHO says, since most are not able to put them on without help.

Children age 6 through 11, however, should wear masks under certain conditions, including local infection rates, whether there’s an adult available to help them, and if they’ll be exposed to elderly people or people with health conditions who are at higher risk of complications from the virus.

Kids 12 and older should wear masks under the same conditions adults would wear them, using the standard social-distancing guidelines, WHO said in its release.

WHO Worked with UNICEF, the International Pediatric Association and other health organizations and experts to come up with the guidelines. Their findings stress that there is limited evidence about how the coronavirus is transmitted in children, but that some evidence shows younger children “may have lower susceptibility to infection compared to adults,” but that this may vary by age. Older children may be more likely to spread the virus than younger ones, according to WHO.

Further, the WHO advises that the benefits of children wearing masks to prevent the spread of COVID-19 “should be weighed against potential harm associated with wearing masks, including feasibility and discomfort, as well as social and communication concerns.”

According to the American Academy of Pediatrics, between July 30th and August 13th, there were more than 75,000 new cases of the coronavirus in children, marking a 24 percent increase in the total. As of last month, more than 340,000 children had tested positive, roughly 9 percent of the total cases in the US.

Medical experts say there are very few medical reasons to preclude most people from wearing cloth face coverings. The Centers for Disease Control and Prevention (CDC) said in a July 14th update that “cloth face coverings are a critical tool in the fight against COVID-19 that could reduce the spread of the disease,” adding that there is “increasing evidence that cloth face coverings help prevent people who have COVID-19 from spreading the virus to others.”