FAIRBANKS — State health officials say vaccination rates in Alaska are improving, but more work needs to be done to maintain herd immunity.

Herd immunity is when a community is protected from disease by immunizing a critical mass of its members.

“The higher the rate of people not getting vaccinated in a community, a school, or in a family, the higher the risk of a disease spreading,” said Dr. Michael Cooper, infectious disease epidemiologist with the state public health division. 

Vaccination rates in Alaska improved from 2012 to 2013, the latest data available, according to Jason Grenn, a spokesman for the Alaska Department of Health and Social Services.

The rate of children ages 19 months to 35 months who had some form of immunization rose from 59.5 percent in 2012 to 63.9 percent in 2013, Grenn said. 

Compared with other the states, Alaska’s rate is a bit lower for younger children getting immunized. 

“We start off a little slow to vaccinate, but then we catch up by kindergarten,” said Matthew Bobo, epidemiologist and deputy program manager of Alaska’s immunization program. “We are basically on par with the rest of the country by kindergarten.”

The state runs various programs to promote vaccinations, including the Vaccinate Alaska Coalition. Free vaccines are offered through federal and state grants. 

Last week was National Infant Immunization Week when state public health centers waived administrative fees for shots.

About 95 percent of public schoolchildren in Fairbanks are vaccinated, according to the Fairbanks North Star Borough School District. The rest have filed a medical or religious exemption.  

It’s not known what the vaccine exemption rate is across the state. Pockets of people in communities along the road system opt out of the vaccine program, Cooper said. 

“We have one of the higher rates of exemptions,” Cooper said. “Mostly, they are religious.”

The physician said he is unfamiliar with which religions oppose immunizations and why.

Immunizations protect people from a host of illnesses, such as measles, chickenpox, whooping cough, rubella, hepatitis and mumps. 

“Vaccines are one of the greatest public health interventions in the last century,” Cooper said. “It has just saved so many lives.”

People who are immunized for a disease still have a small risk of contracting the disease, usually in a mild form. The risk of illness is much greater for those who have no immunizations, Cooper said. 

“You’ve got no protection except for that herd immunity,” he said. 

Contact staff writer Amanda Bohman at 459-7587.