Q. Can one take a Covid booster shot on the Asarah Beteves fast day?
A. Horav Shlomo Miller's Shli'a opinion is that it is preferable to avoid taking the shot on the fast day of Asarah Beteves, since the fasting may cause frailty and weakness that could affect the outcome of the booster shot in some people.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a