Concerns about COVID might have also kept families out of the pediatrician’s office this year, leading their kids to fall behind on their recommended childhood vaccines.

However, according to new data, the downward trend in immunization rates for infants in children in the United States might have started well before the COVID pandemic took hold.

The Research

A study from researchers at the University of Virginia School of Medicine and Stony Brook University in New York and published in the journal Health Equity found that less than 73% of infants in the U.S. are getting all their recommended vaccinations.

For the study, the researchers reviewed data from the National Immunization Survey (NIS)—which is conducted annually by the Centers for Disease Control and Prevention (CDC)—for children aged 19 to 35 months old. The survey collects information on maternal age, education, marital status, child’s age, race/ethnicity, birth order, and poverty status.

The researchers evaluated immunization rates for the seven-vaccine series that is recommended for children. The vaccines included in the series are for diphtheria, pertussis (whooping cough), tetanus, polio, measles, mumps, rubella (German measles), hepatitis B, Hemophilus influenza b, varicella (chickenpox), and pneumococcal infections.

Some of the vaccines in the series are combined into one shot. For example, the MMR vaccine combines the vaccines against measles, mumps, and rubella, with the DTaP vaccine, which immunizes against diphtheria, tetanus, and pertussis.

Several vaccines in the series require multiple doses over several months for full immunity. The influenza shot must be given yearly.

The overall immunization rate for recommended vaccines—while low—has increased by about 30% over the 10-year period the researchers studied. However, the disparities in rates of vaccine uptake between racial and socioeconomic groups have also grown. The researchers concluded that these disparities “negate the success of the increased vaccination rate."

Low vaccination rates mean that the population of the U.S. has not reached herd immunity for many preventable diseases.

Socioeconomic Factors

The study’s findings also showed that some infants and children are less likely to complete a series of immunizations than others.

Children born to mothers with less than a high school education were 27% less likely to get all their shots compared to children whose mothers were college-educated. Children living in families below the poverty line were 30% less like to be fully vaccinated than those with a family income of more than $75,000. Children living between the poverty line and an income of up to $75,000 were 25% less likely to get all of their shots. African American children were about 8% less likely to get their vaccinations than non-Hispanic white children.

Why Are Immunization Rates So Low?

Rajesh Balkrishnan, PhD, professor of Public Health Sciences at the University of Virginia and one of the study’s authors, tells Verywell that several issues come into play with immunization rates in children.

Misinformation and Vaccine Hesitancy

“I think it’s a host of factors, but first of all, there is a significant amount of vaccine hesitancy in this country, just like we’re seeing with the COVID vaccine," Balkrishnan says, citing the example of the lasting misinformation linking vaccines and autism—which has been debunked many times.

Cost

Another factor is that some parents are afraid of the costs of vaccinations. “People are sometimes scared about the costs of these vaccines, but there are workarounds," Balkrishnan says. For example, a federal program called Vaccines for Children provides free vaccines for uninsured, underinsured, and Medicaid-eligible children.

However, other aspects of an immunization appointment, like a doctor’s office visit, can also cost parents. Balkrishnan says there are workarounds to that problem that could help address the disparity, such as clinics and community health centers that can administer vaccines.

Public Health Risks of Low Immunization Rates

Balkrishnan says that the low rate of immunization is a serious public health problem. He finds it shocking that there are yearly outbreaks of measles and mumps in the U.S. “These types of conditions have been eradicated even from lower-income countries which have no resources, and here in the United States, we still have them.”

As changes in the environment occur, Balkrishnan says that he expects to see more frequent disease outbreaks. He adds that the COVID-19 pandemic has also revealed the state of public health in the U.S. and people’s attitudes toward it.

“The COVID pandemic clearly shows how vulnerable we are," Balkrishnan says, adding that there is a laissez-faire attitude about becoming ill with a disease and then treating it—rather than preventing the disease in the first place.

“We cannot wait for diseases to happen, expecting that we have the wherewithal and technologies to treat them,” Balkrishnan says. “The only weapon we have to fight against these types of infectious diseases is vaccines. Parents owe it to themselves and their children to get them vaccinated in the first three years of their life.”

Better education about the importance and safety of all vaccinations, and Balkrishnan says that we “need to mobilize communities around these issues."

If you are unsure which vaccinations that your child needs (and when), you can consult the CDC’s immunization schedule.