I was reminded of that when my youngest daughter woke me up for an early morning cuddle, sneezed in my face, and wiped her nose on my pajamas. I scheduled her flu shot for the next morning.
In the United States, the Centers for Disease Control and Prevention recommends a flu vaccine for everyone 6 months of age and older. This year, after the spread of the “bird flu” H5N1 in cattle, the CDC is urging dairy farm workers to get vaccinated in particular. In late July, the agency announced a $10 million plan to provide free flu shots to people who work with livestock.
The goal is not only to protect workers from seasonal flu, but also to protect all of us from a potentially more devastating outcome: the emergence of a new form of flu that could trigger another pandemic. That hasn’t happened yet, but unfortunately it’s looking increasingly likely.
First, it’s good to remember that flu viruses are always undergoing subtle changes in their genetic makeup. This allows viruses to evolve rapidly, which is why flu vaccines need to be updated each year to reflect which strains are most likely to circulate.
When multiple flu viruses infect an animal, even more dramatic genetic changes can occur. The flu virus genome is made up of eight segments. When two different viruses enter the same cell, they can swap segments.
These replacement events could create entirely new viruses. While it is impossible to predict exactly what the outcome will be, there is always the possibility that a new virus will spread more easily or cause more severe disease than previous viruses.
There are concerns that farm workers with seasonal flu could catch bird flu from cattle, unknowingly becoming reservoirs for deadly new strains of flu, which could then be passed on to those around them. “That’s exactly how we think a pandemic would start,” says Thomas Peacock, a virologist at the Pirbright Institute in Woking, England.
