Influenza viruses are masters of adaptation. They undergo two key processes known as genetic drift and genetic shift. Genetic drift refers to the small, gradual changes in the virus's genetic material that happen over time. These changes can slightly alter the virus's surface proteins, helping it evade the immune system. On the other hand, genetic shift is a more dramatic process where two different influenza viruses combine their genetic material, resulting in a completely new virus. This is how pandemics like the 2009 H1N1 flu can occur.
These processes explain why the flu vaccine needs to be updated every year. The continuous changes in the virus mean that last year's vaccine might not provide full protection against this year's circulating strains. Understanding genetic drift and shift helps us appreciate the complexity of flu viruses and the importance of annual flu vaccination.
Press a button to see how a "drift" or "shift" in sentences can change their meaning, much like a shift or drift in genes can change the appearance of the virus to our immune system.
As you can see, a slight change in the sentence changes its meaning, but not too drastically. But a shift in the sentence can change the sentence to something completely else. This happens with the genes inside the flu virus. A drift confuses our immune system, while a shift really throws it for a loop!
Read more about this phenomenon in viruses (and some bacteria) on this page: https://www.cdc.gov/flu/php/viruses/change.html