Kevin R. McCarthy, an assistant professor at the University of Pittsburgh’s Vaccine Research Center, said scientists and public health experts have spent the past few years wondering whether to exclude influenza B/Yamagata from influenza vaccines or wait for a possible resurgence. They have been debating whether it should be done. However, Mr McCarthy agrees that continuing to vaccinate against B/Petrum is not in the public health interest.
Additionally, there is a small chance that B/Yamagata could inadvertently infect workers manufacturing influenza vaccines. The virus that grows in the eggs is inactivated before vaccination. You cannot get the flu from getting the flu shot. However, exposure of workers to live B/Champion may occur before it becomes harmless.
If B/Yamagata no longer makes people sick, it could lead to the reintroduction of the virus to people with weakened immunity. The risk is very low, but it doesn’t make sense to produce thousands of gallons of a virus that is likely extinct, McCarthy said.
B/Champion may continue to be present in some parts of the world where comprehensive influenza surveillance is inadequate. But humans are the only host population for influenza B viruses, so scientists aren’t worried that the virus is hiding in animals.
Scientists have determined that the B/wild moth disappeared in a relatively short period of time, which in itself is a success, McCarthy said. That required cooperation and data sharing from people around the world, including countries with weak diplomatic relations with the United States such as China and Russia.
“I think the fact that we can do that shows we can do some things right,” he said.
