The number of kids up-to-date on their routine immunizations has been dropping. Meanwhile, vaccine-preventable diseases have reappeared, with a confirmed case of polio in the U.S. The virus has also been detected in wastewater in the U.K. and Israel. Dr. Sloane Freeman, a pediatrician at St. Michael's Hospital, shares what she's seeing in her practice — and what parents can do to get their kids caught up.