Vaccine coverage for children by the age of 2 declined for eight vaccines, the Centers for Disease Control and Prevention said in a new study.
CDC researchers compared the percentage of children vaccinated with recommended shots across two time periods. In the first group, the children were born in 2019 and 2020. In the second group, they were born in 2021 and 2022.
Among the second group, vaccine coverage had declined by the time that the children turned 2 compared with the earlier cohort, researchers reported in the paper, published on March 26 by the CDC’s quasi-journal.
The sharpest declines were for vaccines against influenza, which declined by 7.4 percent to 53.5 percent coverage; rotavirus, which declined by 1.7 percent to 74.2 percent coverage; and pneumococcal disease, which declined by 1.5 percent to 80.5 percent coverage. Influenza vaccine coverage has plummeted in recent years, with a 12 percent drop in coverage since 2019.
Coverage was also slightly lower for vaccines against hepatitis A, hepatitis B, chickenpox, Haemophilus influenzae type b, and polio, the CDC said.
About the same percentage of children had received the measles, mumps, and rubella vaccine, and multiple doses of the diphtheria, tetanus, and pertussis vaccine by the age of 2 in the cohorts, according to the study. The percentage of children who had received no vaccines was unchanged, at 1.2 percent.
The CDC publishes vaccine schedules, which are widely used by states when they require vaccines for school attendance. The CDC in January narrowed recommendations for childhood vaccines, including shots against hepatitis B and rotavirus, but a federal judge recently blocked those changes as litigation proceeds.
The newly published research was based on the CDC’s National Immunization Survey, which monitors vaccination uptake among children and adults.
CDC researchers in the survey collection called households with children aged 19 months to 35 months and asked questions to caregivers, usually parents. If caregivers provided consent, then the children’s doctors were contacted to provide information about which vaccines the children have received. Researchers used the answers and data to form estimates of vaccine coverage.
In 2024, 23 percent of households responded to interview requests. Data was provided by about half of the health care providers for children whose caregivers completed interviews.
The population ended up being 27,392 children, including 1,355 in Texas, 1,027 in Pennsylvania, and 1,000 in New York. Children were included from all 50 states, the District of Columbia, and the territories of Guam and Puerto Rico.
“Maintaining high levels of vaccination and improving coverage among groups and in areas in which rates have declined could help protect children from vaccine-preventable morbidity and mortality,” Holly Hill, a medical officer at the CDC’s Immunization Services Division, and co-authors wrote in the paper.
Limitations included researchers relying on cellphones, which omitted households without them. Authors declared no conflicts of interest.
Coverage had also declined for many vaccines among kindergartners, the CDC said in its most recent paper on that age group, in the summer of 2025.