Nearly nine in 10 Americans who received the first dose of a two-dose Covid-19 vaccine went on to complete the regimen, and most people who received two doses got them within the recommended time frames, federal health officials reported on Monday.
The analyses, by investigators with the Centers for Disease Control and Prevention, included data on tens of millions of Americans who received the Moderna or Pfizer-BioNTech vaccines between mid-December and mid-February.
The percentage of people completing the regimens varied markedly by jurisdiction and between demographic groups, however. Federal health officials urged local vaccinators to take steps to ensure that everyone comes back, including scheduling a return appointment when giving the first shot, sending reminders, and rescheduling missed or canceled appointments.
While the data were “reassuring” over all, C.D.C. researchers said, the first groups receiving the vaccine in the United States — health care workers and long-term care facility residents — had easy access to the second dose, since they were likely to have been vaccinated at their workplace or place of residence.
As vaccines are offered to broader groups of people, the scientists warned, the percentage getting fully vaccinated may drop.
People are not considered fully vaccinated against the coronavirus until two weeks after they receive the second shot of the two-dose regimen (or two weeks after receiving the single-dose vaccine made by Johnson & Johnson).