Scientists said this week that preliminary tests on a prototype of a pandemic flu vaccine based on the deadly H5N1 strain of bird flu have shown promise.
Scientists at Sanofi-Pasteur, the French pharmaceutical company developing the vaccine, said adding another ingredient to the flu shot seemed to boost the potency of lower doses. That would mean that supplies of the key element of the vaccine -- known s the antigen -- could be stretched further, allowing more people to obtain the shots in an emergency.
"This is progress and an important step in pandemic vaccine development," said World Health Organization spokesman Dick Thompson.
Since 2003, the deadly bird flu strain has killed at least 69 people in Asia -- most of them farm workers who came into close contact with infected birds.