A bird flu vaccine made from monkey cells instead of chicken eggs has been reported effective by corporate researchers.
The researchers, from drug company Baxter International, documented the use of monkey cells as a safe alternative for influenza vaccinations.
“Cell culture technology could represent the future of influenza vaccine production,” said virologist John Oxford of The Queen Mary School of Medicine in London.
Scientists had previously been using chicken eggs but they found it difficult to obtain the right type and observed that the virus, H5N1, kills chickens rapidly.
The trial, carried out on more than 250 people and reported in the New England Journal of Medicine, showed the vaccine produced a strong immune response in people who received two doses.
Despite this, Hartmut Erlich, vice-president of global research and development for Baxter's BioScience, found adding an immune system booster called an adjuvant did not improve the vaccination, despite previously helping other bird flu vaccines.
The H5N1 avian flu virus has been responsible for killing 241 people in 15 countries, according to the World Health Organisation, and has become firmly entrenched among birds in much of Asia and parts of Europe, Africa and the Middle East.
Experts fear the constantly mutating virus could change into a form easily transmitted from person to person, perhaps sweeping the world and killing millions.
At least 16 companies are working on vaccines against H5N1.
It is unknown whether they will work against whatever strain might eventually cause a pandemic, but makers agree it is better to be prepared.
Cell-based vaccines would require less advance planning and could be made year-round, it was reported.
Baxter also has created a seasonal flu vaccine made in cells instead of eggs.
The vaccine, called Celvapan, is made in the Czech Republic.
Because it is not possible to test whether the vaccine actually prevents infection, the researchers measured antibodies in their volunteers in Austria and Singapore. They said it induced an immune response similar to the body's defence against a natural virus infection.