A vaccine that protects against death and serious complications from different strains of influenza is a little closer to reality, U.S. researchers say.

Dr. Robert Belshe of Saint Louis University said drug companies now manufacture a different flu vaccine each year to match the strains of influenza researchers predict will circulate.

"However, novel vaccines, capable of inducing long-lasting, broad immunity against divergent strains, including potential pandemic viruses, are highly desirable," the lead author said in a statement.

In the study, 377 healthy adults received three injections of a universal influenza vaccine, known as Bivalent Influenza Peptide Conjugate Vaccine, over a six-month period. Belshe studied a vaccine made with proteins from strains of influenza viruses A and B.

The researchers determined a low dose of the vaccine is well tolerated and safe, Belshe said. It addition, the low-dose vaccine created an immune response similar to levels associated with protecting small animals infected with influenza from serious disease and death. More testing is needed, Belshe said.

Belshe presented the findings at the National Foundation for Infectious Disease Conference for Vaccine Research in Baltimore.