New CDC data released late last week found that vaccination rates among kindergarteners fell below the public health target of 95% last year, and roughly 400,000 fewer children enrolled in kindergarten for the 2020-2021 school year—sparking further concern among experts that an unknown number of children may have fallen behind on routine vaccinations.

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CDC uncovers nationwide drop in kindergarten vaccination rates

In CDC's Morbidity and Mortality Weekly Report (MMWR), researchers found that national coverage declined for three vaccines required in all public and private schools during the 2020-2021 school year.

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For the report, the agency tracked school entry vaccination data among kindergartners in 47 states and the District of Columbia, excluding Alaska, Illinois, and Virginia, as well as vaccine exemptions in 48 states and the District of Columbia, MedPage Today reports.

In addition, researchers analyzed "provisional enrollment" policies, which let students enroll without completing required vaccinations or with an exemption while they complete a vaccination schedule, and "grace periods," which give children the ability to attend school for a certain number of days with no proof of complete vaccination or exemption.

Overall, more than half of the states included in the report observed an increase in the number of students that required a grace period or provisional enrollment—something that became more common amid Covid-related disruptions, said Shannon Stokley, deputy director of CDC's Immunization Services Division.

Typically, national vaccine coverage for kindergarteners is around 95%. However, for the 2020-2021 school year, it fell below 94% for the first time in 12 years, according to Stokley.

Nationally, coverage for the measles, mumps, and rubella (MMR) vaccine was 93.9%, while coverage for both the diphtheria, tetanus, and acellular pertussis (DTaP) vaccine and the varicella vaccine was 93.6%, according to Ranee Seither, of the CDC's National Center for Immunization and Respiratory Diseases.

According to the report, 2.2% of kindergartners had at least one vaccine exemption, and an additional 4% of kindergartners who did not have an exemption were not up to date on their MMR shot during the 2020-2021 school year.

Experts voice concern over declining vaccination rates

While national coverage is still considered relatively high—with a 1% decline in routine vaccination rates compared with 2019-2020—CDC's experts still see a cause for concern, MedPage Today reports.

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"This means that there's 35,000 more children in the United States during this time period without documentation of complete vaccination against common diseases," said Georgina Peacock, acting director of CDC's Immunization Services Division, who was not involved in the report.

Notably, since 400,000 fewer children than expected enrolled in kindergarten in 2020-2021, enrollment reported across 48 states was 10% lower than 2019-2020. "This is concerning, because we don't know how many of these children were vaccinated," Peacock noted.

Signs of declining childhood immunization rates surfaced in the early days of the pandemic, including declining vaccine orders from states under a federally funded program for uninsured patients, the New York Times reports.

According to the CDC report, Covid-related disruptions likely played a significant role in the decline, with a higher number of canceled non-emergency appointments, missed routine appointments, and eased vaccine requirements for students participating in remote learning.

While some families were eager for their children to get vaccinated against Covid-19 and other diseases, others grew increasingly hesitant and were more resistant than ever, said Phoenix-based pediatrician Gary Kirkilas.

"All the rumblings about vaccines for kids and the misinformation that was going on at the time—that sort of amplified that particular segment of families, where 'I'm distrustful of the flu vaccine and then I'm also distrustful of the Covid vaccine and maybe I'm starting to be distrustful of vaccines in general,'" Kirkilas said.

"We haven't seen outbreaks and that's probably representative of the fact that families were staying home during the pandemic,'' Peacock said. However, experts worry that could change if children continue to fall behind on their shots. (AP/Modern Healthcare, 4/21; Sun, Washington Post, 4/21; Mueller/Hoffman, New York Times, 4/21; Firth, MedPage Today, 4/21; Mahr, Politico, 4/21)