State health officials reported three new measles cases Wednesday in an outbreak that has now sickened 24 children.

Even though the case count has doubled this week, health investigators say the outbreak’s development isn’t presenting them with any surprises. All of the cases involve unvaccinated Somali children from the age of 10 months to 5 years. Fifty percent of the current cases have been hospitalized.

“They all make sense based on the exposures that we were aware of and what we were watching for,” said Kris Ehresmann, infectious disease director at the Minnesota Health Department.

Even so, health officials have redoubled their public health efforts.

At a meeting Wednesday night, Ehresmann said guidelines call for Somali children and all children in Hennepin County to be on an accelerated schedule for the measles-mumps-rubella (MMR) vaccine, with 28 days between the required two dosages.

She said the last large outbreak in Minnesota was in 1990, when 460 cases were reported and three people died.

“We want to make sure that we are increasing that wall of protection in the community,” Ehresmann said.

She was among speakers at the Cedar-Riverside People’s Center to brainstorm among health professionals and Somali leaders about how best to increase vaccination rates and inform the community.

Asli Ashkir, a registered nurse and Somali educator at the health department, said there is no fact-based link between autism and vaccinations, a concern she has seen and heard expressed by many families.

Still, she never orders parents to vaccinate their children, but explains the facts so they can make their own decision.

Lynn Bahta, a registered nurse and public health nurse with the department, told the crowd of about three-dozen people that vaccination rates have fallen dramatically among Somalis compared to the rest of Minnesota. In 2004, the rates were the same. In 2014, only 42 percent of Somali children were vaccinated for MMR compared with 89 percent for non-Somalis.

The health professionals also stressed the importance of keeping children out of child-care centers if they have been potentially exposed and are unvaccinated.

Exposure to the first symptoms of measles can take up to three weeks. Symptoms often start out resembling those of a cold, with fever, cough, runny nose and watery eyes. Within 8 to 14 days, a rash begins at the head and spreads down to the rest of the body. In severe cases, measles can produce lasting lung and brain damage.