The report from the Centers for Disease Control and Prevention also shows continued decline in immunization rates for three other childhood vaccines that prevent diphtheria, tetanus and pertussis (DTaP), polio and chickenpox among kindergartners in 2021.
The latest data underscores concerns that growing parental resistance to routine childhood immunizations is fueling a resurgence in vaccine-preventable diseases, such as the recent measles outbreaks in Minnesota and Columbus, Ohio, that sickened more than 100 children last year. The pandemic has magnified the issue because of the politicization around coronavirus vaccines, and the lingering consequences of school closures and fewer children going to the doctor on immunization rates.
“We know measles, mumps, and rubella vaccination coverage for kindergartners is the lowest it has been in over a decade … and that is something to be concerned about,” Georgina Peacock, the CDC’s director of immunization services, said in a briefing.
While a two percentage point drop in measles vaccination rates may seem insignificant, health officials and experts warn that even the smallest decline allows the virus to spread more quickly, causing outbreaks in clusters of unvaccinated children. Measles is so contagious that people who may not know they are being exposed can become infected and spread the virus to family members or other contacts before they show symptoms.
In addition to being potentially lethal, the measles virus weakens the immune system and makes a child more vulnerable to other diseases such as pneumonia and diarrhea — an effect that lasts for months after the body clears the measles infection.
Sean O’Leary, a pediatric infectious diseases doctor, called the recent outbreaks of vaccine-preventable diseases like measles and polio “alarming.” Vaccination in childhood is essential because “it equips children’s immune systems to recognize and resist disease so they can develop and live healthy lives into adulthood,” he said at the briefing.
O’Leary, who takes care of hospitalized children, said many of those could be prevented with the “simple, safe step of keeping your child up to date on recommended vaccines.”
The federal data shows nine states and the District of Columbia with vaccination coverage among kindergartners below 90 percent, including Ohio and Minnesota. That’s the largest number of states to fall below that level in CDC published data, which goes back to 2009-2010. New York, Nebraska, North Carolina and Tennessee are among the 12 states with MMR vaccination rates above 95 percent.
Kindergartners’ coverage for all four childhood vaccines — to prevent measles, diphtheria, tetanus and pertussis (DTaP), polio and chickenpox — was about 93 percent nationwide in the 2021-2022 school year, down from 94 percent in 2020-2021, and 95 percent in 2019-2020.
The decline means that more than 275,000 kindergartners may not be completely protected against these diseases, according to the CDC.
Several factors are behind the decline. Pandemic-related disruptions to the health-care system delayed pediatric checkups. In part as a result, providers have ordered fewer doses from the federal program that provides vaccines for half of all American children. In some cases, schools also lack the staff to ensure parents submit health documentation in time.
And concerns over the value of the coronavirus vaccine are increasingly spilling over into routine immunizations.
“We have seen some hesitancy in vaccines during the pandemic related mostly, I think, to the covid vaccine. And this could in some cases, have translated over to routine vaccinations,” said the CDC’s Peacock. “And that’s something that we’re watching very closely.”
Preventable diseases spread quickly, she warned, pointing to the recent measles outbreaks in Ohio and Minnesota.
The CDC recommends children get two doses of MMR vaccine, with the first dose at 12 to 15 months, and the second dose between 4 and 6 years old. One dose of the vaccine is about 93 percent effective in preventing measles; two doses are about 97 percent effective.
In the Columbus outbreak, most of the 83 children infected were old enough to get the shots, but their parents chose not to do so, officials have said, resulting in the country’s largest outbreak of the highly infectious pathogen in 2022. If no new cases are reported by Jan. 30, authorities will likely declare that outbreak over, said Myles Bell, a Columbus health department spokesman.
Minnesota reported 22 cases of measles between June and November last year, but they occurred in several clusters. That pattern was more concerning than one large outbreak, such as the one the state experienced in 2017.
The clusters “remained contained like small campfires, but each had the potential to drastically expand to a forest fire that could have had more severe consequences,” said Doug Schultz, a spokesman for the Minnesota health department. Vaccine hesitancy was a contributing factor in both outbreaks, health officials have said.
Peacock and O’Leary also pointed to the case of paralytic polio in a New York man this summer that prompted worry that low childhood immunization rates and rising vaccine misinformation could result in the disease’s resurgence, decades after vaccination had eliminated it in the United States.
“I think those are all evidence of the fact that we do have pockets in the United States where we have low vaccine coverage among children … and also in these particular communities a need for increasing vaccination rates,” Peacock said in an interview.
The CDC this week launched an initiative to get routine immunizations for adults and children back on schedule. Officials are giving health-care providers more information and strategies to help them talk about vaccines and work more intensely with community groups in areas where vaccination rates are very low.
Rupali Limaye, an associate professor at Johns Hopkins University who has studied vaccine hesitancy, said the overall decline in childhood immunization rates is worrying, and the drop in measles vaccination in particular, is dangerously low and “quite concerning.”
She has spoken to hundreds of parent, church and other community groups in the last three years about the coronavirus vaccine. Many people may not have had issues with the routine immunization schedule before the pandemic, she said. But confusing messaging about the need for children to get the coronavirus vaccine “has affected their decision-making to these routine immunizations,” Limaye said.
Immunization advocates say it’s hard to raise vaccination rates without a clearer understanding of why they fell.
“Most recent surveys show parents still overwhelmingly support childhood vaccines, so is it an awareness issue?” asked Erica DeWald, director of strategic communications at Vaccinate Your Family, an immunization advocacy group. “Or do we need to identify access issues that arose as a result of the pandemic? We need to continue collaborating with community partners to identify and address the underlying barriers to vaccination.”
Dan Keating contributed to this report.