October 19, 2021 11:28 am COVID Q&A: Top Doctors Talk Vaccine Mix & Match, Efficacy and School Mask Mandates Top Boston doctors talk about the “mix and match” approach to COVID vaccine booster shots, variations in vaccine efficacy and school mask mandates. US & World Videos 3:25 Principal dancer bids farewell to Boston Ballet 12:05 Heart monitors of the future could be peel-and-stick like temporary tattoos 0:30 Speak now: Sebastián Agudelo 4:25 Speak now: Sue O'Connell 3:59 Speak now: Megan Paladino