Story highlights According to a CDC report, 1.3% of kids born in 2015 received no vaccinations by age 2

In 2001, only 0.3% of kids age 19 to 35 months had received no vaccines

This was the third consecutive school year that saw an increase in vaccine exemptions, according to a report on kindergarteners

(CNN) The percentage of young kids in the US who received no vaccine doses has continued to rise, as have vaccine exemption rates, according to two reports published Thursday by the US Centers for Disease Control and Prevention.

While coverage for a number of vaccines "remained high and stable overall," the segment of unvaccinated kids under age 2 rose from 0.9% for those born in 2011 to 1.3% for those born in 2015, according to one report . In 2001, only 0.3% of kids between 19 and 35 months had received no vaccine doses.

"Although the number of children who have received no vaccinations by age 24 months has been gradually increasing, most children are still routinely vaccinated," wrote authors from the CDC's National Center for Immunization and Respiratory Diseases. "Continued evaluation of prevalence and reasons for nonvaccination is needed, as are improvements in access to and delivery of age-appropriate vaccinations to all children."

Still, coverage in this age group surpassed 90% for a number of vaccines, including poliovirus, Hepatitis B, varicella, and measles, mumps and rubella.

Those who were least likely to be fully vaccinated: uninsured children and those on Medicaid, compared to privately insured kids, despite being eligible for a federally funded program that administers free vaccines. Kids outside of metropolitan areas were also less likely to be covered when compared to those in major cities.