Kindergarten vaccination rates dip below target for 2020-2021

National vaccination coverage for kindergarteners during the 2020-2021 school year fell below the nationwide target of 95% coverage, according to a new Centers for Disease Control and Prevention analysis.

This includes MMR, DTaP and varicella vaccines, which protect against multiple diseases including measles, mumps, rubella, chicken pox, whooping cough, tetanus and chickenpox. The analysis did not include COVID-19 vaccines, which were authorized for children 5 and older after the end of the 2020-2021 school year.

Although the drop was small -- down to 94%, representing a 1% drop from the prior school year -- the CDC says the new analysis underscores growing concerns that pandemic disruptions could inadvertently lead to a growing number of vaccine-preventable illnesses among children.

"This might not sound like much, but it amounts to at least 35,000 more children across the United States that entered kindergarten without documentation of complete vaccinations against common diseases," said Dr. Georgina Peacock, director of the Division of Human Development and Disability at the CDC.

Researchers attributed the drop in vaccination rates to pandemic-related causes, including lower school enrollment, missed pediatrician appointments and lower data reporting from schools.

In addition to the 35,000 children who entered school without completed vaccinations, remote and in-person school enrollment was approximately 10% lower than the previous year, according to data from 48 states and Washington, D.C.

"This means around 400,000 fewer children entered kindergarten than expected. Those children also might not be up to date on their routine vaccinations," said Peacock.

Mississippi had some of the highest vaccine coverage rates, with over 95% for MMR, DTaP, varicella, while Washington, D.C., had some of the lowest reported coverage rates, with 78-79% coverage per vaccine.

During the 2020-2021 school year, fewer states were able to report data back to the CDC due to pandemic-era capacity problems. Forty-seven states and the District of Columbia contributed to the new analysis, but Alaska, Illinois and West Virginia did not report vaccination coverage data due to the impact of COVID-19 on data collection, and were excluded from the analysis.

Some states allowed for eased vaccination requirements for remote learners and reduced submission of documentation by parents. This meant less time for school nurses to follow-up with students missing documentation or vaccines, fewer staff members to conduct kindergarten vaccination coverage assessment and reporting activities, and lower response rates from schools.

"This is further evidence of how the pandemic-related disruptions to education and health care could have lingering consequences for children. The good news is, routine vaccination coverage remains high and we can recover ground loss during the pandemic," said Peacock.

Despite concerns about rising vaccine hesitancy, the rate of children with religious or medical exemptions remained low, at 2.2%, and the percentage of exempt children actually decreased in 37 states.

The report noted that more than half of the states' schools are allowing under-vaccinated children to attend school under provisional enrollment, which allows a student without complete vaccination or an exemption to attend school while completing a catch up vaccination schedule or with a grace period status, which is a set number of days during which a student can be enrolled and attend school without proof of complete vaccination or exemption, according to Dr. Shannon Stokely, associate director for Science at the Immunization Services Division of the CDC.

"[With] most schools back to in-person learning, extra effort is needed to catch up children who missed vaccines and to maintain high levels of routine childhood vaccinations and equitable coverage to help protect children, their families and their communities against vaccine preventable diseases," said Peacock.

Dr. Grace Cullen is an internal medicine resident at the Mayo Clinic in Rochester, Minnesota, and a contributor on the ABC News Medical Unit.