The U.S. National Institutes of Health (NIH) said on Friday that it has begun an early-stage study on its experimental vaccine targeting six strains of influenza virus.

The vaccine candidate, FluMos-v2, is designed to offer protection against four strains of the influenza A virus and two strains of influenza B virus, the health agency said.

"An ideal universal influenza vaccine could be taken less frequently than once a year and protect against multiple strains of influenza virus. With each new universal influenza vaccine candidate and clinical trial, we take another step closer to that goal," said Hugh Auchincloss, acting director of the National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH.

The study is expected to enroll 24 healthy volunteers, aged between 18 and 50, who will receive two intramuscular injections of FluMos-v2 at a gap of 16 weeks, NIH said.

FluMos-v2 has been designed by researchers at NIAID's Vaccine Research Center.

COVID vaccine maker Moderna said on Wednesday its flu vaccine had generated a stronger immune response against all four A and B strains of the influenza virus compared to traditional flu shots in a late-stage trial.