(NewsNation) — The 2022-2023 flu vaccine provided “substantial protection” over the winter flu season, according to a release from the U.S. Centers for Disease Control and Prevention. 

Preliminary data from the CDC found the vaccine was 43% effective against flu-related hospitalizations of all adults.

In kids, the vaccine was 68% effective in preventing illnesses severe enough to require hospitalization, and 42% effective for pediatric visits to the emergency department.

Concurrently, the flu vaccine was 35% effective at preventing hospitalization in seniors, according to the CDC.

Effectiveness of the influenza vaccine varies by season.

Officials generally are pleased if a flu vaccine is 40% to 60% effective.

Kids and seniors are typically at highest risk of severe disease from the flu.

The dominant flu strain was the kind typically associated with higher rates of hospitalizations and deaths, particularly among older people.

According to Brendan Flannery, who is responsible for the CDC’s flu vaccine effectiveness data, there have been some years the vaccines were virtually ineffective in people 65 and older. But this season’s vaccine has done unusually well, with the best results seen in at least 10 years.

The flu hit earlier than usual this season, according to CDC data, and has caused 25 million illnesses, 280,000 hospitalizations and 18,000 deaths since October.

Annual flu vaccines are recommended for everyone 6 months and older in the U.S.

At least 111 flu deaths have been reported in children, the most since the 199 reported in the 2019-2020 season.

Despite the CDC characterization that the vaccine provided substantial protection, Dr. Sarah Long of Drexel University was underwhelmed with the modest results and pointed out the need for better flu vaccines.

“It is still disappointing,” Long said. “That the vaccine was a good match and yet effectiveness was still modest.”

The Associated Press contributed to this report.