Children will be heading back to school in the next couple of weeks. But those under 17 years old are the least vaccinated of any eligible age group able to receive a COVID vaccine. Teenagers like 17-year-old Angely Keosann are taking it upon themselves to encourage their age group to get vaccinated. Keosann is one of 27 "Philly Teen VAXX Ambassadors" — teenagers who volunteered through the Philadelphia school district to educate their peers about the vaccine.