Scientists may have discovered the virus mutation that caused flu vaccines administered in 2014 and 2015 to be highly ineffective.
New flu vaccines are created ever year in an effort to combat the quickly mutating virus and anticipate which strains will circulate, but new research suggests last year's vaccine designers failed to take into account certain mutations, the Wistar Institute reported.
The vaccine creates antibodies that match certain strains of the flu, but certain antibodies can be ineffective if the virus acquires mutations at the sites (called antigenic sites) where they are supposed to bind. In this occurrence, known as antigenic drift, mutations occur at these sites and often render vaccines ineffective.
Our studies show that flu viruses recently acquired mutations in critical regions that are recognized by our immune system," said Scott Hensley, Ph.D., Assistant Professor at The Wistar Institute, who led a study published online by the journal Cell Reports. "These new mutations likely contributed to the ineffectiveness of flu vaccines during the 2014 [to] 2015 flu season."
To make their findings, the researchers pinpointed 10 different viral mutations that occurred between 2014 and 2015 and differed from viral strains used to create the most recent vaccine. They also looked at sera, which is the clear part of the blood that holds viral antibodies, from humans and ferrets exposed to the H3N2 vaccine strain that circulated during this period. They noticed mutations in a specific region of H3N2 viruses made the vaccine ineffective. The team was also able to modify the H3N2 vaccine strain so that it matched the strain with mutations causing the problems.
"I have a really talented team of researchers who are very good at quickly dissecting the specificity of flu antibody responses," Hensley said.
The World Health Organization (WHO) has now recommended the flu vaccine be appropriately updated for the next season.
