Every year the race begins to produce the next flu vaccine for the upcoming seasons, based on what strains are circulating, how they’re spreading, and how effective our current vaccines are. But this process is never exact, and mistakes can and sometimes are made, nullifying the previous years’ work. But a new study reveals that scientists might be able to create a “universal” vaccine that will offer protection from a variety of strains.
“The reason researchers change the vaccine every year is that they want to specifically match the vaccine to the particular viruses that are circulating, such as H1N1. If the vaccine is just a little bit different to the target virus, it is not expected to offer much protection,” says Dr. Jeffery Taubenberger, who led the study published in mBio. “What we have done is design a strategy where you don't have to think about matching the vaccine antigen to the virus at all.”
The new technique works by creating a “cocktail” of key surface proteins, or antigens, expressed by influenza viruses, the combination of which differ from strain to strain. While “there are 16 different hemagglutinin [surface protein] subtypes that circulate in birds and are thought to be the basis for current and future influenza pandemics,” explains Taubenberger, the study decided to focus on just four of them: hemagglutinin H1, H3, H5 and H7.
The choice of surface proteins was important, because H1 and H3 have been the major cause of human flu outbreaks since 1918, and H5 and H7 are responsible for the recent bird flu epidemics. By injecting mice with the “investigational” cocktail of proteins, they found that 95% of the animals were protected against eight different lethal strains of influenza, compared to only 5% of mice that received a mock vaccination.
“Almost all of the animals that were vaccinated survived, including mice that were challenged with viruses that expressed hemagglutinin subtypes that were not in the vaccine at all,” said Taubenberger. “What that suggests is that this approach really gives us broad spectrum protection, and could serve as a basis for an effective pre-pandemic vaccine.”
In addition to this, they found that the vaccine offers protection for at least six months, and works well in older mice. This last point is important, because current flu vaccines are less effective in older patients. The researchers, from the National Institute of Allergy and Infectious Diseases, say that these findings are very positive, and suggest a “practical strategy for developing a vaccine with amazing, broad protection.”