By Ahmed Aboulenein and Michael Erman WASHINGTON (Reuters) -The White House expects the rate of vaccination in its fall booster campaign to pick up over the coming weeks, and its COVID response coordinator Dr. Ashish Jha on Friday characterized the initial pace as “a really good start.” The United States in September started rolling out the updated COVID shots, redesigned to take on both the currently circulating BA.4 and BA.5 Omicron subvariants as well as the original version of the virus targeted by all previous COVID vaccines and boosters. The so-called bivalent boosters are available to a…