Despite an increase in the immunization rate of the 7-vaccine series in the United States (US) over the past 10 years, vast disparities still exist, preventing many infants from being protected from preventable diseases, according to the findings of a study recently published in Health Equity.

The 7-vaccine series provides immunization against diphtheria, pertussis, tetanus, poliovirus, measles, mumps, rubella, hepatitis b, Haemophilus influenze type b, varicella, and pneumococcal infections. In its Healthy People 2020 initiative, the US Department of Health and Human Service’s Office of Disease Prevention and Health Promotion set a goal of 90% completion of each of the vaccines in the 7-vaccine series.

“The objective of this study was to assess the 7-vaccine immunization rate in infants 19–35 months over a decade spanning 2009 to 2018 and to understand factors that affect immunization, and to provide the most recent benchmark for the 7-vaccine series immunization rate during the ‘pre’ COVID-19 pandemic time period,” the authors explained. Immunization rates of the 7-vaccine series as well as its predictors were assessed using results obtained from the National Immunization Survey from 2009 through 2018.

Findings of the analysis revealed that the rate of immunization of the 7-vaccine series increased approximately 30% over the 10-year period analyzed. Despite this increase, only 72.8% of infants had received the recommended 7-vaccine series in 2018, which is significantly lower than the 2020 goal of 90%.

Data analysis showed significant disparities in vaccination rates based on race, family income, as well as education level. “As compared with non-Hispanic whites, non-Hispanic blacks were less likely to receive the 7-vaccine series (OR: 0.92; 95% CI, 0.86-0.98), whereas Hispanics were more likely to receive the 7-vaccine series (OR: 1.22; 95% CI, 1.15-1.30),” the authors reported.

Findings also showed that infants from families below the poverty threshold level were approximately 30% less likely to receive the series compared to those from families with an income of greater than $75,000 per year (OR, 0.69; 95% CI, 0.65-0.75). Additionally, compared with infants whose mothers obtained a college degree, infants whose mothers obtained less than a high school education were nearly 27% less likely to receive the vaccine series (OR, 0.73; 95% CI, 0.67-0.79).

“Free vaccination coupled with no additional fees, linked with potential programs that are frequently accessed by low-income families, could be a potential solution to increase the 7-vaccine series rates and should be considered,” the authors stated.

Disclosure: One author disclosed ties to pharmaceutical industry. Please refer to the original article for a full list of disclosures.


Kulkarni AA, Desai RP, Alcalá HE, Balkrishnan R. Persistent disparities in immunization rates for the seven-vaccine series among infants 19–35 months in the United States. Health Equity. [Published online March 15, 2021] doi: 10.1089/heq.2020.0127