Flu season has come early this year in parts of the northern hemisphere, and many people are scrambling to get their annual vaccination. That ritual may someday be history.
In a first for any infectious disease, a vaccine against flu has been made out of messenger RNA (mRNA) – the genetic material that controls the production of proteins. Unlike its predecessors, the new vaccine may work for life, and it may be possible to manufacture it quickly enough to stop a pandemic.
We become immune to a flu strain when our immune system learns to recognise key proteins, called HA and NA, on the surface of the flu virus. This can happen either because we have caught and fought off that strain of flu, or because we received one of the standard vaccines, most of which contain killed flu virus.
Flu constantly evolves, however, so those proteins change and your immunity to one year’s strain does not extend to following year’s. For this reason, a new vaccine has to be produced each year. Most flu vaccines are grown in chicken eggs or cell culture, a process that takes at least six months.
This time lag means that the World Health Organization has to predict months in advance which viruses are most likely to be circulating the following winter. Drug companies then make a new vaccine based on their recommendations. Of course, these recommendations can be wrong, or worse, when a completely new flu virus causes a pandemic, its first waves can be over before any vaccine is ready.