the omicron subvariant ba.2 with nevada, colorado, d.c. and new york all seeing cases rise. >> reporter: is the term booster kind of getting outdated? >> so the fourth shot is basically like a seasonal recommendation. in fact, i do think all americans will need to get used to the idea. >> reporter: medical experts say those eligible for a fourth shot should consider their personal risk factors. for many americans, a new and important choice coming soon. catie beck, nbc news. the discussion on boosters comes as cases rise in the united states, including touching the west wing. we mentioned jen psaki testing positive in news breaking this morning. secretary of state antony blinken is considered a close contact because he had dealings with an israeli official who tested positive. blivgen himself negative but will be isolating to some degree. switching back to ukrainian,