Just as millions of children are heading back to school, the World Health Organization says those aged 6 to 11 should wear masks in some cases to help fight the spread of coronavirus. The recommendations presented Monday follow the widespread belief that children under 12 are not considered as likely to propagate the virus as much as adults. Children in general face less severe virus symptoms than do adults, with the elderly the most vulnerable to severe infection and death. Now WHO says decisions about whether children aged 6 to 11 should wear masks should consider factors like whether COVID-19 transmission is widespread in the area where the child lives; the child’s ability to safely use a mask; and adult supervision when taking the masks on or off. Acknowledging gaps in both research and understanding of the virus, WHO said kids under age 6 should not wear masks, while those 12 to 18 should wear them just like adults should — notably in cases where physical distancing cannot be ensured and in areas of high transmission. WHO advises a “risk-based approach” for kids aged 6 to 11 that balances various factors.