Flu season is right around the corner. There will soon be banners outside pharmacies, posts on social media, adverts on the telly/radio, and emails in your inbox urging you to “Get Your Flu Shot Now.”
What is ‘Antigenic Drift’?
Like all vaccines, flu vaccines are also designed to reduce the severity of infection. However, your immune system is in a constant race against the flu virus. Just like the COVID-19 virus and its many mutations, the influenza virus also rapidly changes into new variants.
Vaccine manufacturers have to update the flu shot to try to keep up. After identifying a new flu variant, it takes about six months to update the vaccine. This time different lag gives the virus an opportunity to mutate again. This phenomenon is called antigenic drift, and can reduce the effectiveness of the flu vaccine for that season. It’s like trying to shoot a moving target.
Are mRNA vaccines an effective solution?
nRNA vaccines are being looked at as a potential solution to this problem – via the production of a universal flu vaccine.
It’s a vaccine that does not need to be updated each year because it is designed to protect against all or most flu variants. Scientists and researchers are exploring several ways to develop this dream universal flu vaccine.
There are 20 known subtypes of influenza. Prior to the development of mRNA vaccines, it wasn’t feasible to make a single flu vaccine against all 20 subtypes due to the complexities and costs of manufacturing.
Unlike traditional vaccines, mRNA vaccine production is faster and simpler. mRNA vaccines provide the genetic sequence of the protein and then use the body’s own cells to generate that protein in its natural structure. This makes it relatively easy to incorporate multiple antigens in one vaccine formulation. A case in point are the bivalent COVID-19 vaccines.
The hurdles
There are still several challenges before a universal flu mRNA vaccine can be made available.
Scientists still don’t know which antigens induce strong immune responses. Also, when a vaccine dose gets divided into 20 or more antigens, the dose of one or more of those antigens may drop below the threshold needed for protection.
In the meantime, two seasonal influenza mRNA vaccines are currently in human clinical trials. If successful, they may offer more effective protection from the annual flu than our current flu vaccines.
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