Vaccination Coverage by Age 24 Months, Children Born 2018–2019 — United States

In brief. The Advisory Committee on Immunization Practices (ACIP) recommends routine vaccination against 14 diseases in a child's first 24 months. Among U.S. children born in 2018–2019, coverage stayed high and stable for most vaccines, and the National Immunization Survey–Child found no overall drop tied to the COVID-19 pandemic. But coverage did fall among children below the federal poverty level and in rural areas, and gaps by race and ethnicity, income, insurance and place persist. Providers should review each child's vaccination history at every visit, recommend the vaccines due, and address parents' hesitancy.

How the survey works

The National Immunization Survey–Child (NIS-Child) phones randomly dialled households with children aged 19–35 months. Parents or guardians answer a telephone interview and are asked for consent to contact the child's vaccination providers, who are mailed a questionnaire; the answers are combined into a full vaccination history. Children born in 2018–2019 came from data collected in 2019–2021: 29,598 with adequate provider data. In 2021 the household response rate was 22.9%, and provider data were adequate for 51.5% of completed interviews. Coverage by 24 months was estimated with the Kaplan-Meier method, except for the hepatitis B birth dose (by 3 days) and rotavirus vaccine (by 8 months); two doses of hepatitis A vaccine were also measured by 35 months, the oldest age available.

National coverage

Compared with children born in 2016–2017, coverage rose for most vaccines.

Only two measures were below 70%: two doses of hepatitis A (47.3%) and two doses of influenza vaccine (63.9%). The combined 7-vaccine series covers DTaP, polio, measles, Hib, hepatitis B, varicella and pneumococcal vaccines. The 0.9% with no vaccinations meets the Healthy People 2030 target of below 1.3%.

By birth year, 2011–2019, coverage was stable for most vaccines, with recent rises for the hepatitis B birth dose, rotavirus, two influenza doses and two hepatitis A doses by 35 months.

Who is missed

Insurance made the biggest difference. Uninsured children, and those on Medicaid or other insurance (the Children's Health Insurance Program, military coverage, the Indian Health Service and others), had lower coverage than privately insured children for every vaccine except the hepatitis B birth dose, which was lower only among the uninsured.

The share with no vaccinations by 24 months was eight times higher among uninsured than privately insured children.

• Race and ethnicity. Compared with non-Hispanic White children, coverage was lower for most vaccines among Black children, and for MMR, varicella, rotavirus, two influenza doses and the combined series among Hispanic children. Coverage was highest among Asian children and lowest among Black children.
• Poverty. Children below the poverty level had lower coverage for every vaccine except the hepatitis B birth dose.
• Place. Children outside metropolitan areas had lower coverage than those in principal cities for every vaccine except the hepatitis B birth dose. By state, coverage varied widely — two influenza doses ranged from 39.7% in Alabama to 84.0% in Rhode Island.

The pandemic

The youngest children in the study, born in 2019, turned 1 in 2020 and 2 in 2021, so many had doses due after the pandemic was declared in March 2020. Overall coverage was similar or higher for children who turned 2 in or after March 2020. A closer analysis, though, found the combined 7-vaccine series fell 4–5 percentage points among children below the poverty level or in rural areas. MMR coverage was 10 percentage points lower for children who turned 13 months in April–May 2020 than for those who turned 13 months before or after, but caught up to pre-pandemic levels by 19 months. The 2022 survey will include more children born just before or during the pandemic.

Closing the gaps

• Willingness. Depending on the vaccine, an estimated 6.5%–31.3% of non-vaccination was attributed to parental hesitancy. CDC's Vaccinate with Confidence strategy aims to build confidence and prevent outbreaks. Proven measures include strong provider recommendations, raising vaccines at every visit, reminder and recall notices, standing orders, and state and local immunization information systems that bring a child's history together.
• Cost and access. The Vaccines for Children (VFC) programme pays for all recommended vaccines for eligible children — those 18 and under who are Medicaid-eligible, uninsured, American Indian or Alaska Native, or underinsured. It needs enough participating providers, and families need to know how to use it. Vaccinating in pharmacies, emergency departments, hospitals and specialty clinics could help underserved communities.

Recent measles outbreaks and a diagnosed case of polio show that pockets of unprotected children exist even in a well-vaccinated country. Parents and providers need to keep every child up to date.

Limitations

• Low household response rates (21%–26% in survey years 2017–2021), and adequate provider data for only 49%–54% of completed interviews, leave room for selection bias.
• Weighting for non-response and households without phones may not remove all bias.
• Coverage is wrong if providers did not return questionnaires or did not record vaccines accurately. A total-survey-error assessment of 2021 data found coverage underestimated by 3.1 percentage points for MMR, 4.4 for the hepatitis B birth dose and 8.7 for the combined 7-vaccine series; a meaningful change in bias from 2020 to 2021 was judged unlikely.

Corrected: the report's limitations name the "combined -vaccine series," dropping the 7.

Sources

• Hill HA, Chen M, Elam-Evans LD, Yankey D, Singleton JA. Vaccination Coverage by Age 24 Months Among Children Born During 2018–2019 — National Immunization Survey–Child, United States, 2019–2021. MMWR Morbidity and Mortality Weekly Report, CDC.