Experiments involving mice, ferrets and monkeys may provide the key to a universal flu vaccine.

Investigators used a two-step immunization approach to elicit infection-fighting antibodies that attacked a diverse array of flu virus strains, according to a press release from the National Institute of Allergy and Infectious Disease, part of the National Institutes of Health. This represents a step forward in research to create a universal flu vaccine.

“Generating broadly neutralizing antibodies to multiple strains of influenza in animals through vaccination is an important milestone in the quest for a universal influenza vaccine,” NIAID Director Dr. Anthony S. Fauci said. “This significant advance lays the groundwork for the development of a vaccine to provide long-lasting protection against any strain of influenza.”

An effective universal vaccine could have a major effect on controlling the flu, which claims an estimated 250,000 to 500,000 lives annually, including an average of 36,000 in the United States, he added.