Every year, people are expected to get the latest flu vaccine.
Unlike other vaccines that only need to be taken once in a lifetime, or only periodically, the flu mutates so frequently that there are constant updates to the vaccine based on what the World Health Organization recommends.
Even with the updates, the vaccine is not always foolproof in preventing people from getting sick. Some years, the strains in the vaccine don't exactly match up with what actually ends up spreading. That was especially true in 2009, when the US faced an outbreak of swine flu.
"Even though they've seen the virus for many years, there's so many changes so that almost nobody is protected," Eliud Oloo, Sanofi's manager of structure, genomics, and informatics told Business Insider.
And the virus is still deadly. The WHO estimates about 250,000 to 500,000 people a year die from the flu.
Outbreaks like that have people wondering, could we one day have a "universal" vaccine — a single shot that could protect against decades of flu mutations?
As a way to get closer to a universal vaccine, researchers at vaccine-maker Sanofi are starting to look for vaccines that might provide broader protection against the flu. That way, instead of a shot once every year, the vaccine could broadly protect against the virus even as it evolves over the course of a few years. Pulling this off will require new, synthetic vaccines that are unlike the vaccines we use today.
That's no small feat: "It's understanding how the virus is going to change through the coming years and developing these brand new synthetics that will ultimately have as part of the vaccine only the key ingredients that will cover all of them," Harry Kleanthous, the US head of research for Sanofi Pasteur told Business Insider.
Kleanthous said this could one day be what a "universal vaccine" looks like, as opposed to the one-shot approach that people might expect.
The new vaccines could broadly cover certain flu strains (today's flu vaccines have either three or four strains in one shot). The vaccines against those strains could be general enough to face off against any mutation that the virus has taken.
That way might be easier than trying to counter ever single strain of the virus that's ever been a problem.
"You don't have to have just one that covers the whole universe," Kleanthous said. If you're able to have broad vaccines that protect against the different flu subtypes, you could ideally just use whichever one makes the most sense in a given outbreak. "You just need to have it all available on the shelf and then stay in tune with what circulates, and just pick the one that makes sense," he said.
The idea's still in the pre-clinical phase. Keanthous said ideally it'll be in human trials in a few years. Plus, because the broad vaccines will have to show how they work over a number of years, it still might be some time to see results.
But if these broader flu vaccines work, researchers might be able to use similar methods to tackle HIV and the common cold (rhinovirus), two diseases that don't have vaccines.