Researchers change the vaccine every year because they know that even If the vaccine is just a little bit different to the prevailing strain, it will not offer much protection. They said they know the importance of specifically matching the vaccine to the particular viruses that are circulating, such as H1N1.
In the new study, researchers at the National Institute of Allergy and Infectious Diseases (NIAID) created a virus-like particle vaccine cocktail that can help prevent against 16 different strains thought to be the basis for current and future influenza pandemics. These include H1 and H3, subtypes because they have been the pivotal cause of human seasonal flu outbreaks since 1918, and H5 and H7 subtypes as they have been responsible for the recent bird flu outbreaks and have pandemic potential.
The hypothesis behind the study was that the presentation of different viral proteins would help develop cross-protective immunity that would provide broader protection against multiple subtypes. According to the principal investigator of the study.
“We have designed a strategy where you don’t have to think about matching the vaccine antigen to the virus at all,” said Jeffery Taubenberger from the Laboratory of Infectious Diseases at NIAID.
When researchers injected mice with the cocktail, they found that 95% of mice were protected against a lethal exposure to eight different influenza strains expressing seven different influenza A subtypes. Even the mice that were challenged with viruses that expressed hemagglutinin subtypes (H2, H6, H10, and H11) that were not in the vaccine at all were protected. This is a very positive outcome suggesting that the cocktail vaccine could serve as a basis for an effective pre-pandemic vaccine.
In stark comparison only 5% of the mice receiving mock vaccinations were protected.
Further experiments showed that the vaccine was not only durable but it worked well in older mice. The latter is crucial given that elderly people are more prone to the ‘flu’ and the current vaccines are not as effective in older people as they are in the younger lot, said researchers.
“These initial findings are very positive and suggest a promising and practical strategy for developing a vaccine with amazing, broad protection,” said Taubenberger.