The number of Michigan schoolchildren waiving vaccines has dropped by more than a third under a state rule change making it more difficult for parents to obtain a waiver, state officials announced Thursday.

As of November 2015, 2.8 percent of Michigan K-12 students had a vaccine waiver on file compared to 4.9 percent in fall 2014, based on preliminary numbers collected from schools by the Michigan Department of Health and Human Services.

In raw numbers, that's nearly 8,000 fewer vaccination waivers, down 39 percent from fall 2014, the department said.

Michigan has long had among the highest vaccine-waiver rates in the country, making its children and larger communities more vulnerable to disease outbreaks.

Department of Health and Human Services officials are cheering the latest numbers as a public health win.

"This improvement in our vaccination coverage rates means that more kids are protected from outbreaks and serious vaccine-preventable diseases," Dr. Eden Wells, HHS chief medical executive, said in the HHS news release announcing the preliminary data. "Unfortunately, we have not eradicated some very serious diseases that affect children and adults alike. We continue to see outbreaks of pertussis, (whooping cough) and chickenpox in areas of Michigan, as well as nationwide."

Database: Vaccine-waiver rates by county

Schools are required to collect vaccination records each fall for kindergartners, seventh-graders and any child in another grade transferring from another school system.

Between fall 2014 and 2015, the kindergarten waiver rate dropped from 5.2 percent to 3.3 percent; the seventh grade rate dropped from 4.6 percent to 2.8 percent; and the rate for transfer students dropped 4.3 percent to 2.5 percent, according to the HHS.

State officials credit the declines to a rule change implemented in January 2015.

In the past, Michigan parents could waive vaccines by simply signing a paper at their school stating they had a philosophical opposition to vaccines.

Health officials suspected some waivers being obtained simply for convenience because it was easier to sign a waiver than get the immunizations.

Starting in January 2015, Michigan parents still can get a waiver, but now must get the paperwork at their county health department and sit through an education session about vaccines and the diseases they are intended to prevent.

Parents also must sign a form saying they understand they may be putting their own children and others at risk by refusing the shots.

"By ensuring that parents have the opportunity to address and discuss concerns with their local health department, we're providing parents with knowledge they can use when making a decision about vaccinating their child," HHS Director Nick Lyon said in the HHS news release.

However, there has been backlash against the new rules from people who say it undermines parental choice and there is an effort under way to gut the new rules.

Last month, House Bills 5126 and 5127, by Rep. Tom Hooker, would prohibit the department from enforcing waiver requirements not mandated in state law, including the immunization education discussion.

In December 2014, MLive.com published an investigation of vaccination rates in Michigan and found a third of Michigan elementary schools had waiver rates high enough to put them at risk of an outbreak of whooping cough or measles, the most contagious vaccine-preventable diseases.

Many of those clusters of unvaccinated children are in affluent and well-educated communities, such as Birmingham, Bloomfield, Rochester and Grosse Pointe, the MLive investigation found. Read the entire series here.

Within schools, outbreaks of diseases, such as measles, whooping cough or chicken pox, are particularly problematic for children or adults in the building with medical issues that prevent them from being vaccinated or who have suppressed immune systems, such as a person undergoing chemotherapy.

Beyond the school walls, whooping cough and measles can easily spread to other vulnerable people in the community, such as babies too young to be vaccinated, elderly persons and people undergoing chemotherapy or otherwise have a suppressed immune system.

Michigan children entering kindergarten must show proof of immunization for measles, pertussis, polio, mumps, rubella, hepatitis B, chicken pox, diphtheria and tetanus -- unless a parent signs a waiver.

By seventh grade, students must be immunized against meningococcal and receive a DTP or DTaP booster for diptheria, tetanus and pertussis. Those vaccines also can be waived by parents.

Michigan is one of 20 states that allows parents to obtain a waiver for reasons beyond religious or medical concerns. These are classified as "philosophical" waivers, which in fall 2014 comprised 71 percent of all waivers.

The national median waiver rate for kindergartners was 1.7 percent for fall 2014 compared to 5.2 percent in Michigan, according to the federal Centers for Disease Control. Michigan had the fifth-highest rate in the country behind Idaho, Vermont, Oregon and Alaska in percentage of kindergartners who have waived at least one vaccine.

Julie Mack is a reporter for MLive.com. Email her at jmack1@mlive.com, call her at 269-350-0277 or follow her on Twitter @kzjuliemack.