A key federal advisory committee voted unanimously Friday to recommend emergency authorization of an additional shot for all recipients of Johnson & Johnson’s COVID-19 vaccine at least two months after their initial dose, a sign that 15 million Americans will likely be cleared for a second J&J inoculation as soon as next weekend.

If implemented, the recommendation from the Food and Drug Administration’s expert panel would effectively transform Johnson & Johnson from its original formulation as a “one and done” vaccine into a two-dose series akin to those produced by Pfizer and Moderna, with a similar profile in terms of safety and effectiveness.

“I think this, frankly, was always a two-dose