PCC, a pediatric electronic health records company, gathered vaccine information from 1,000 independent pediatricians nationwide. Using the week of February 16 as a pre-coronavirus baseline, PCC found that during the week of April 5, the administration of measles, mumps and rubella shots dropped by 50 percent; diphtheria and whooping cough shots by 42 percent; and HPV vaccines by 73 percent.

The doses that states distribute in a federally funded program for uninsured patients called Vaccines for Children have also dropped significantly since the beginning of March. The Massachusetts health department said its doses were down 68 percent in the first two weeks of April, compared with the previous year. Minnesota reported that its doses of measles, mumps and rubella vaccine dropped by 71 percent toward the end of March.

In Washington State, dozens of practices and clinics have had to reduce hours or even temporarily close. The state already had its biggest measles outbreak in nearly 30 years last year.