The strains for the next flu season's vaccine have already been chosen by the World Health Organization. It's heading to production and will be ready for arms and noses this fall.

Will it be effective? We won't know until this time next year.

"They have to predict the future, right? And that's hard to do," said Dr. Florian Krammer, a microbiologist at the Icahn School of Medicine at Mount Sinai. "If the strains change in the meantime, there's nothing that can be done about it.”

Which is why scientists like Krammer have been working for nearly a decade to create a universal flu vaccine that protects against all influenza strains.

"We were always thinking that antibodies could only target one strain of influenza, and they don't cross-protect against the other strains, but it turned out that there are rare antibodies that can actually cross-neutralize," Krammer said.

Krammer's lab is funded by the National Institutes of Health and is the first to conduct clinical human trials for a universal vaccine in the United States.

There are some trials underway in Eastern Europe.

They're targeting the part of the virus that provokes an immune response: a protein shaped like a mushroom.

The current flu vaccine targets the cap of the mushroom, which can quickly change or drift, as the virus moves from host to host.

Krammer's lab is among several focusing on the stalk of the so-called mushroom.

"That part doesn't change over time," he said. "What we are trying to do is to trick the immune system into actually recognizing that part, making antibodies against that part."

Some vaccines are also less effective because certain strains grow poorly in eggs, which is how many vaccines are manufactured. That's what happened with this year's dominant strain, H3N2.

Flu vaccines have been grown in eggs, like the one seen in the video above, since the 1940s. Now, researchers are building on that technology to create a universal vaccine, no longer limited to eggs.

Previous trials with animals were promising, but scientists are still a ways away from a universal flu vaccine. It could take another decade before one is available for widespread use.

"We made so much progress in the last five years," Krammer said. "Things might actually speed up. But I think people shouldn't give up hope.”

The possibility of winters free of aggressive flu epidemics could be in the not-too-distant future.