Researchers at Johns Hopkins Bloomberg School of Public Health have discovered a genetic mutation in the FluMist intranasal flu vaccine that has the potential to be altered to enhance the vaccine’s protective effect.
This flu season marks the second that the panel that advises the Centers for Disease Control and Prevention (CDC) on vaccines has recommended that FluMist not be used in the U.S. The Advisory Committee on Immunization Practice found that the vaccine had grown less effective in recent years, possibly due to shifts in circulating flu strains, and researchers have been searching for ways to restore its effectiveness.
In the new study, the Bloomberg School researchers discovered a previously overlooked mutation, present within two of the viral strains used in the vaccine, that reduces virus production. When the researchers reversed the mutation in one of the viruses, the virus became more active, making copies of itself – which is known as replicating – more quickly in cultured human nasal cells and inducing a stronger production of immune proteins.
The findings appear in the journal Vaccine.
“Only one component of FluMist – the one targeting the Type A H1N1 virus – has been failing in the U.S. recently,” says Dr. Andrew S. Pekosz, professor in the Bloomberg School’s department of molecular microbiology and immunology. “It’s not clear exactly why it has failed but this mutation we identified could be used to make that component of the vaccine a little stronger, thereby improving vaccine efficacy. We now see the possibility of altering this mutation and perhaps others in the vaccine to optimize the vaccine’s protective effect, perhaps for different age groups.”