An influential U.S. advisory panel will discuss expanding eligibility for COVID-19 vaccine booster shots to all adults Friday, a move that could make the shots available nationwide as early as this weekend. … Pfizer asked U.S. regulators last week to allow boosters of its COVID-19 vaccine for anyone 18 or older. The FDA is expected to sign off on Pfizer’s application before the advisory panel meets Friday. The final step — CDC’s official recommendation — could come soon after the meeting.