A scientist works in the lab at the Moderna Inc. headquarters in Cambridge, Massachusetts. | Adam Glanzman/Bloomberg via Getty Images

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The Food and Drug Administration approved Moderna’s mRNA flu vaccine this week — a major public health breakthrough for an administration that’s been troublingly down on vaccines.

The flu is a gigantic and costly illness, causing 1 billion infections and 300,000 deaths each year. But this new shot, built on advances from the Covid-19 pandemic, is expected to outperform the standard flu vaccine that we’ve used, largely unchanged, for the past 80 years.

The new shot fixes a problem that has long bedeviled the traditional vaccine: the gap between how quickly the flu virus mutates and how slowly vaccines are produced. The flu is changing constantly. But under current methods, manufacturing a flu vaccine — which, to my enormous fascination, most commonly involves secret chicken farms — takes six to eight months.

That long lag often means the virus circulating during flu season isn’t the one the vaccine was designed to target. But the new mRNA vaccine works differently: Instead of using a weakened or dead virus to trigger an immune response, mRNA vaccines contain genetic instructions that train the immune system to fight influenza.

mRNA vaccines also take less time to manufacture, so they can be produced closer to flu season. In a clinical trial, older adults who received Moderna’s mRNA vaccine were 27 percent less likely to get the flu than those who received the standard vaccine.

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A world without flu?

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Public health experts are justifiably hyped about mRNA technology. In addition to this new flu shot, researchers are developing mRNA vaccines against diseases including malaria, tuberculosis, and HIV.

But when it comes to influenza, mRNA isn’t the endgame. The real white whale is a “universal flu vaccine” — a shot that’s at least 75 percent effective against influenza A, the most dangerous type of flu virus, and lasts at least a year.

The challenge, again, is that the virus keeps mutating. Flu vaccines, whether mRNA or conventional, teach the immune system to recognize a viral protein called hemagglutinin and then fight off the virus.

But hemagglutinin is a part of the flu virus that mutates often. To make a more durable vaccine, researchers are trying to either target parts of the virus that rarely change or teach the immune system to simultaneously recognize many different strains.

Several vaccines that use these approaches are already in clinical trials. And if they succeed, the flu shot could hypothetically become more like the measles vaccine — providing years of protection in one go, instead of requiring annual updates.

In other words, we’re used to thinking of the flu as a routine winter hazard, but that might not always be the case. If you can persuade people to get their shots, at least.

One link for later

➨ Go ahead, take your time. Three etiquette experts tell Vox that, in most casual situations, you can run 10 to 15 minutes late without appearing inconsiderate. But that guideline is very culturally and contextually dependent, which is bad news for chronically late people like myself. I prefer to think it’s a result not of rudeness, but of polychronicism.

Before you go…

Did you know…that the Fast & Furious franchise, now on its 10th movie, is (loosely) based on a 1998 magazine article? The author of that piece is still a working journalist, so it would not appear he got his money’s worth from Hollywood.
Today’s trivia: What’s the fourth largest Great Lake? (You can find this and other brain puzzles in Vox’s daily crossword. Look for the answer in Monday’s edition.)
Yesterday’s trivia: Yesterday we asked you for the name of the Nickelodeon game show hosted by Marc Summers. That would be Double Dare, which just celebrated the 40th anniversary of its first episode. The show is credited with influencing a generation of children’s media.

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