(NewsNation) — U.S. health officials said the number of children given exemptions from vaccinations required by schools is at its highest level ever.

In data published Thursday, the Centers for Disease Control and Prevention wrote that 3% of kindergarten children were able to get excused from getting a vaccine in their state during the 2022-2023 school year. In the 2011-2012 school year, it was 1.6%.

Exemptions increased in 40 states as well as the District of Columbia. Ten states reported an exemption from at least one vaccine for at least 5% of kindergartners, the CDC wrote.

However, the national vaccination rate remained steady at 93% — the same as the year before. It is still lower than the 95% vaccination rate from before the COVID-19 pandemic, however.

The reason the vaccination rate was able to stay the same despite the increase in children with exemptions is that there are three groups included in vaccination statistics: those who get all the shots, those who get exemptions and those without exemptions who didn’t get their shots and paperwork completed when data was collected.

The CDC warned that “clusters of undervaccinated children can lead to outbreaks.”

Experts say this could partly be because more parents are questioning routine childhood inoculations since the COVID-19 pandemic. Although doctors and other medical experts have maintained vaccines are safe and effective against the coronavirus, there were still protests nationwide over mandates requiring children to take them.

“Whether because of an increase in hesitancy or barriers to vaccination, the COVID-19 pandemic affected childhood routine vaccination,” the CDC wrote.

Rates were also influenced by state laws that can make it easier or harder to obtain exemptions.

“The bad news is that it’s gone down since the pandemic and still hasn’t rebounded,” Dr. Sean O’Leary, a University of Colorado pediatric infectious diseases specialist, told the Associated Press. “The good news is that the vast majority of parents are still vaccinating their kids according to the recommended schedule.”

States and local jurisdictions set vaccination requirements for school attendance as well as the conditions and procedures needed to be exempt from them, according to the CDC. Data on the number of children in kindergarten who meet, are exempt from or are in the process of meeting requirements for vaccines for diseases including measles, mumps and rubella is reported to the CDC annually.

States allow children with medical conditions that prevent them from receiving certain vaccines to be exempt. They can also be excused from the vaccines on religious or nonmedical grounds as well.

Idaho had the highest percentage of kindergartners who received exemptions at 12%, while other states like New York only had 0.1% of kindergartners who had an exemption. By far, Hawaii, with 6.4%, saw the largest increase in exempted students over the last school year.

“Sometimes these jumps in exemptions can be very local, and it may not reflect a whole state,” O’Leary added.

The Associated Press contributed to this report.