Vaccination Coverage by Age 24 Months Among Children Born in 2021 and 2022 — National Immunization Survey-Child, United States, 2022–2024

Abstract

The National Immunization Survey-Child monitors coverage with recommended routine childhood vaccines. For data collected in survey year 2024, which include children born in 2021 and 2022, the household response rate (23.4%) and availability of adequate provider data for children with completed interviews (51.4%) were comparable to those from earlier survey years. For most vaccines, coverage by age 24 months was similar among children born in 2021 and 2022 and those born in 2019 and 2020. Declines in coverage of 1–2 percentage points were observed for the primary series of Haemophilus influenzae type b conjugate vaccine, the birth dose of hepatitis B vaccine, ≥4 doses of pneumococcal conjugate vaccine, and rotavirus vaccine. Coverage with ≥2 doses of influenza vaccine by age 24 months decreased from 61.0% among children born during 2019–2020 to 53.5% among those born during 2021–2022. Coverage was lower among Vaccines for Children (VFC) program–eligible children than among those who were not VFC-eligible and differed substantially by jurisdiction. Compared with non-Hispanic White children, coverage with many vaccines was lower among non-Hispanic Black or African American and Hispanic or Latino children; coverage was highest among non-Hispanic Asian children. Coverage was also lower among children living in poverty and those living in more rural areas. 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. The Community Preventive Services Task Force recommends several interventions to increase vaccination, including standing orders for vaccination, immunization information systems, and vaccination programs in organized child care centers and in Special Supplemental Nutrition Program for Woman, Infants, and Children settings. Other factors demonstrated to be effective include strong provider recommendations, targeted messages from credible and trusted sources, and increased participation in the VFC program.

Introduction

As a public health strategy, immunization of young children has been critical to reducing morbidity and mortality due to vaccine-preventable diseases and has been found to be highly cost effective (1). During 2024, the most recent year of data collection available for this report, U.S. vaccination recommendations included receipt of routine vaccines and a monoclonal antibody to protect children against 16 potentially dangerous infections by age 24 months (2). For approximately 30 years, coverage with recommended childhood vaccines has been monitored by the National Immunization Survey-Child (NIS-Child).* Data from NIS-Child are used to estimate coverage at national, regional, state, and selected local area levels and for three U.S. territories (Guam, Puerto Rico, and the U.S. Virgin Islands).^† Data are stratified by the child’s year of birth, and vaccination status by age 24 months (or other milestone age) is assessed. This report describes trends in national coverage with recommended vaccines over time (excluding COVID-19 vaccine)^§ and provides coverage estimates by Vaccines for Children (VFC) program eligibility,^¶ race and ethnicity, poverty status, urbanicity, and jurisdiction of residence.

Methods

Data Collection

U.S. households that include children aged 19–35 months are identified through random-digit–dialing and invited to participate in NIS-Child. Household interviews with the adult most knowledgeable about the child’s vaccination history (usually a parent) are conducted via cellular telephone,** and consent is requested to contact the child’s vaccination providers and the state immunization registry. Once consent is obtained, a questionnaire is mailed to all of the child’s providers requesting detailed information about vaccines received by the child since birth. This information is synthesized into a comprehensive vaccination history for each child, which then serves as the basis for the coverage estimates included in this report.

Among households with eligible children identified in 2024 (the most recent survey year available), the household interview response rate^†† was 23.4%, and adequate provider data^§§ were available for 51.4% of children with completed interviews. NIS-Child uses a complex weighting process that includes adjustments for household nonresponse, provider nonresponse, and households without cellular telephones. Weights are calibrated to known population totals by age, sex, race and ethnicity, and geography to improve representation. Nonresponse adjustments are incorporated in the weighting to reduce potential bias. In addition, statistical modeling techniques such as imputation and variance estimation methods are used to handle missing data and account for the complex survey design (NIS-Child: A User’s Guide). Children born during 2021–2022 were identified from data collected during survey years 2022–2024; data from 27,392 children were available for analysis. Application of survey weights to reflect the complex sample design of NIS-Child resulted in a weighted total sample size of 7,454,623.

Data Analysis

Data from multiple survey years were combined and then stratified by year of birth to create birth cohorts for analysis. Kaplan-Meier techniques were used to estimate vaccination coverage by age 24 months for most vaccines. Exceptions include the birth dose of hepatitis B vaccine (HepB), which is considered received if administered during the first 3 days of life, and the rotavirus vaccine series, which is not meant to be given after age 8 months, 0 days. Because of a change in vaccination recommendations in 2020 and a long period of eligibility for catch-up vaccination, coverage with ≥2 doses of hepatitis A vaccine (HepA) was estimated by age 35 months (the maximum age within the scope of NIS-Child data collection) as well as by age 24 months.^¶¶ Differences in coverage estimates were evaluated using z-tests at an α-level of 0.05. Estimated coverage nationally and by jurisdiction among children born during 2021 and 2022 was compared with that among children born during 2019 and 2020. For data stratified by sociodemographic characteristics, subgroup estimates were compared with those for a designated referent group. Analyses used weighted data and were performed using SAS software (version 9.4; SAS Institute) and SUDAAN software (version 11; RTI International). This activity was reviewed by CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy.***

Results

Recent Trends in National Vaccination Coverage by Birth Year

The largest difference in estimated vaccination coverage by age 24 months between children born in 2021 and 2022 and those born in 2019 and 2020 was a 7.4 percentage point decrease in coverage with ≥2 doses of influenza vaccine (Table 1). Smaller decreases were observed in coverage with the birth dose of HepB (1.8 percentage points), rotavirus vaccine (1.7), ≥4 doses of pneumococcal conjugate vaccine (PCV) (1.5), and the primary series of Haemophilus influenzae type b conjugate vaccine (Hib) (1.0). Nonsignificant decreases were observed for coverage with nearly all of the remaining vaccines. Coverage remained at or above 90.0% for ≥3 doses of poliovirus vaccine (92.1%), ≥3 doses of HepB (91.6%), ≥1 dose of measles, mumps, and rubella vaccine (MMR) (90.8%), and ≥1 dose of varicella vaccine (VAR) (90.0%). The lowest estimates of coverage were for ≥2 doses of HepA by age 24 months (46.8%) and ≥2 doses of influenza vaccine (53.5%). The percentage of children who received no vaccinations (1.2%) continued to meet the Healthy People 2030 target of ≤1.3%. Longer term trends (2011–2022) by single-year birth cohort reveal coverage consistently at or above 90.0% with ≥3 doses of poliovirus vaccine (range = 91.0%–93.8%), ≥1 dose of MMR (range = 89.8%–92.3%), ≥3 doses of HepB (range = 89.8%–92.6%), and ≥1 dose of VAR (range = 89.1%–91.2%) (Supplementary Figure). Although coverage with the birth dose of HepB increased by 10.6 percentage points during 2014–2019, coverage has steadily declined for the past three birth cohorts. Coverage with ≥2 doses of influenza vaccine declined significantly (12.0 percentage points) since 2019.

Vaccination Coverage by Selected Sociodemographic Characteristics

Coverage with all vaccines was lower among children born in 2021 and 2022 who were eligible for VFC than among those who were not VFC-eligible (Table 2). Differences in coverage ranged from 2.5 percentage points (≥3 doses of HepB) to 22.4 percentage points (≥2 doses of influenza vaccine). By race and ethnicity, coverage with most vaccines was lower among non-Hispanic Black or African American children than among non-Hispanic White (White) children (Supplementary Table 1); exceptions include ≥1 dose of HepA, ≥2 doses of HepA (by age 35 months), the birth dose of HepB, ≥3 doses of HepB, and ≥1 dose of VAR. Compared with White children, coverage with ≥4 doses of diphtheria, tetanus toxoids, and acellular pertussis vaccine (DTaP) (5.5 percentage points), the full series of Hib (4.0), ≥4 doses of PCV (8.9), rotavirus (10.1), ≥2 doses of influenza vaccine (6.9), and the combined 7-vaccine series^††† (7.1) was lower among Hispanic or Latino children. Coverage with approximately one half of the vaccines assessed was higher among non-Hispanic Asian (Asian) children than among White children, with percentage point coverage differences ranging from 2.1 (≥3 doses of HepB) to 14.6 (≥2 influenza vaccine doses). Asian children were less likely than White children to have received no vaccinations (0.6% versus 1.4%). Coverage with all vaccines was lower among children living below the federal poverty level than among those living at or above the poverty level (Supplementary Table 2), with percentage point differences ranging from 3.5 (≥3 doses of HepB) to 18.1 (rotavirus). Compared with children living in a metropolitan statistical area (MSA)^§§§ principal city (a measure of urbanicity), coverage with most vaccines was lower among children living in non-MSAs. Coverage among children living in an MSA nonprincipal city was lower (1.9 percentage points) only for ≥1 dose of HepA.

Vaccination Coverage by Jurisdiction

Variation in coverage with selected vaccines was also observed by jurisdiction (Table 3), especially for ≥2 doses of influenza vaccine, which ranged from 25.2% (Mississippi) to 78.3% (Massachusetts). Coverage with ≥2 doses of influenza vaccine among children born during 2021–2022 decreased compared with coverage among children born during 2019–2020 in 30 (54.6%) of 56 states and local areas.

Discussion

For most vaccines monitored by NIS-Child, estimated coverage by age 24 months for children born in 2021 and 2022 was similar to coverage among those born in 2019 and 2020. Healthy People 2030 objectives were met for ≥1 dose of MMR (target ≥90.8% versus 90.8% achieved) and receipt of no vaccinations (target ≤1.3% versus 1.2% achieved) but not for ≥4 doses of DTaP (target ≥90.0% versus 80.7% achieved). Although coverage with most vaccines has been maintained, the decline in coverage with the HepB birth dose for the past three birth cohorts is a notable trend. The birth dose, recommended within 24 hours of birth, according to the immunization schedule that was in place for all children in this study, serves as a universal safeguard against early hepatitis B virus (HBV) transmission. For infants born to mothers who are hepatitis B surface antigen (HBsAg)–positive, the birth dose, administered together with hepatitis B immune globulin, provides the critical first line of protection against perinatal HBV infection. Without this protection, approximately 90% of U.S. infants born to women who are HBsAg-positive will develop chronic infection with HBV, and approximately 25% of them will eventually die from chronic liver disease (Clinical Overview of Perinatal Hepatitis B | CDC). The HepB birth dose is also an important safety net protecting against HBV infection for infants born to the 12%–16% of pregnant women in the United States who, despite having health insurance and receiving prenatal care, are not tested for HBsAg during their pregnancy (3). Infection can also be transmitted through contact with blood or fluids from HBV-infected family or community members before infants have the opportunity to complete the 3-dose vaccination series.

A large decline in coverage with ≥2 doses of influenza vaccine resulted in its lowest level in more than a decade (51.8%). Vaccination against influenza decreased among children during the COVID-19 pandemic and has not yet recovered to prepandemic levels (4). A recent study among children aged 6 months–17 years reported that 30.9% of children had a parent hesitant about influenza vaccination, with higher prevalences of hesitancy among parents of younger children (5). Common reasons reported by parents for not obtaining an influenza vaccination for their children include a lack of belief that their child would get very sick from influenza (48.2%), concern about vaccine safety and side effects (43.3%), and a perception that the vaccine was not highly effective (37.0%) (4). The lack of concern over severity of influenza is relevant given that during the 2024–25 U.S. influenza season, the cumulative influenza-associated hospitalization rate was the highest since 2010–11 (6), and 280 pediatric deaths caused by influenza were reported, exceeding the highest number reported during a nonpandemic season since pediatric influenza deaths became reportable in 2004; 89% of those deaths occurred in children who were not fully vaccinated against influenza (7).

Differences in vaccination coverage by sociodemographic characteristics such as race and ethnicity, poverty status, MSA status, health insurance status, and eligibility for the VFC program persist, all of which have been documented in previous studies (8–10). VFC is designed to ensure that all children have access to vaccines, regardless of their family’s ability to pay. Growing a robust network of VFC-enrolled providers and ensuring the program reaches eligible children are essential to guaranteeing that all children have access to vaccination services.

Limitations

The findings in this report are subject to at least three limitations. First, the household response rates (22%–27% during survey years 2020–2024) and the availability of adequate provider data for only approximately one half of those with completed household interviews during these survey years could lead to selection bias that was not completely eliminated by the use of survey weighting adjustments. Without adequate information about study nonparticipants, the direction of such bias is unknown. Second, both the sampling procedure and the collection of data by household interview rely on respondents having cellular telephones; omission of households without cellular telephones could also be a source of selection bias, although the effect would likely be small: according to a 2025 Pew Research Center survey, 98% of adults in the United States own a cellular telephone. Finally, vaccination histories could be incomplete if not all providers were identified by interview respondents or if some providers did not respond to requests for vaccination information. Previous assessments of total survey error in NIS-Child have indicated that vaccination coverage is underestimated by up to 9 percentage points for certain vaccines. The 2024 total survey error estimates were similar to those from previous years for the vaccines assessed (NORC at the University of Chicago, CDC, unpublished data, 2025).

Implications for Public Health Practice

Vaccines have substantially reduced severe illness, hospitalization, and death and have saved approximately $2.7 trillion in societal costs (1). Although national vaccination coverage remained stable for most vaccines, lower coverage among certain population subgroups and in some jurisdictions is creating an increased risk for outbreaks of vaccine-preventable diseases. During 2025, a total of 2,144 confirmed measles cases were reported in the United States, the largest number of annual cases since measles was declared eliminated in 2000. Among these cases, 93% occurred in persons who were not vaccinated against measles or whose vaccination status was unknown. The preliminary number of reported pertussis cases in 2024 was higher than that reported in 2019, before the COVID-19 pandemic. Because national and state data might obscure what is happening locally, state and local health departments are encouraged to analyze data from their immunization information systems to identify opportunities for increased attention and intervention.

Some of the strategies for helping parents make informed decisions and increasing vaccination coverage include strong, evidence-based provider recommendations, development of targeted messages from credible and trusted sources, and increasing participation in the VFC program (10). In addition, the Community Preventive Services Task Force recommends several other interventions to increase vaccination, including standing orders for vaccination, reminders from health care providers, immunization information systems, and vaccination programs in organized child care centers and in Special Supplemental Nutrition Program for Woman, Infants, and Children settings. (The Community Guide | CDC). Additional evaluation of the behavioral and social drivers of vaccination can be helpful for the design of targeted interventions to engage with families about the importance of routine childhood vaccinations and their role in supporting children’s health (4,5). Interventions such as these can increase vaccination coverage, reverse declines in vaccination coverage associated with the COVID-19 pandemic, and help protect all children from the morbidity and mortality associated with vaccine-preventable diseases.