The Biden administration is reportedly considering recommending a booster shot of the COVID vaccine. But almost a third of Americans over 12 haven’t gotten their first dose yet. Some local health departments are pioneering a new way to reach the hold-outs through micro-influencers. These aren’t the big stars of social media with millions of fans and their own product lines or whatever. Rather, these folks have smaller, local followings in specific communities. The city of San Jose, California and the Knight Foundation recently partnered with about 50 Vietnamese, Latinx and Black micro-influencers to promote vaccines. Marketplace’s Meghan McCarty Carino speaks with Andy Lutzky, the city’s chief communications and marketing officer. He says San Jose’s vaccination rate rose 12 percentage points over the summer, in part because of the influencers’ work.