Shipments come on the heels of a severe flu season and record deaths in children.
The drug's prevention efficacy was 76% in the 450-mg group, 61% in the 300-mg group, and 58% in the 150-mg group.
Maternal vaccination reduced the risk of influenza by 51% for infants up to 2 months old.
The company said an mRNA flu vaccine has the potential to more closely match circulating strains.
Experts warn that the federal vaccine advisory group's decision to revisit childhood immunizations and its controversial vote on thimerosal will undermine confidence in vaccines.
Also, the group recommends Merck's RSV preventive for babies and weighs in on the upcoming season's flu vaccines.
This week's meeting of ACIP is likely to mark its end—for now—as a vaccine advisory body.
The group is expected to vote on thimerosal, despite no evidence of harm, and will discuss the MMRV use in young children.
Former ACIP members pushed back on claims of public mistrust and warned dismantling has critically weakened US vaccination programs.
Estimated effectiveness was 68% against influenza B and 32% against type A.
