As many as three of four Colorado children who died of flu complications may not have been vaccinated, state health officials said Thursday.The deaths of three toddlers and one baby in the past five weeks make this flu season the worst for children in the past five years, the health officials said. During the each of the past four flu seasons, from October to May, only one or two children died in Colorado, said Dr. Ken Gershman, chief of the communicable-disease program at the state health department.

“It is very tragic,” The Denver Post quoted Gershman as saying. “It’s tear-jerking to read these stories. They are horrendous.”