"It just sort of incubates and new forms can come back, so in the severe /*flu*/ epidemics (which this may or may not be), it can come back more severely months later," Stanford University immunologist Mark Davis said.
Davis is currently doing research on how and why some immune systems react differently to vaccines.
Right now, next year's flu vaccine is ready to be manufactured. But with the new virus entering the scene, scientists have two options: create two vaccines or add the new virus to the existing ones.
Davis favors having just one vaccine.
"So people don't have to come in twice; the more convenient you make it, the more people will use it," he said.
Having just one vaccine will also be less costly for the manufacturers and patients.
The vaccine or vaccines will be available in September, just enough time to make or add the new virus.
In light of the new threat, a record number of people are expected to get vaccinated.
"If they could get vaccinated now, they would be flocking in, so it's going to be very popular and hopefully they'll make plenty for everybody," Davis said.
The plan is to make enough for the more than 300 million Americans.