WASHINGTON (AP) — U.S. health advisers are meeting to tackle who needs boosters of Johnson & Johnson’s single-shot COVID-19 vaccine and when. Advisers to the Food and Drug Administration on Friday also will examine data suggesting that booster of a competing brand might provide better protection. The national booster campaign kicked off last month with a third dose of the Pfizer vaccine offered to certain high-risk groups at least six months after their initial vaccination. Thursday, the same FDA panel recommended a lower-dose Moderna booster for similar people. For J&J, the panel will consider if another dose is needed as early as two months.