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No one will stop you from getting the booster you want

Mixing and matching vaccine brands is officially on the table in the United States. But that option may soon be billed as the B-list choice.

Last night, CDC director Rochelle Walensky gave the green light to the Moderna and Johnson & Johnson booster shots, the long-awaited follow-up to a similar recommendation given last month to the Pfizer formulation. As the endorsement reads, anyone eligible for an extra shot — including now tens of millions more Americans — should be able to choose the brand of booster they like. But discussions among a panel of experts who advised Walensky pointed to a caveat: The agency has yet to issue its final clinical guidelines on who, in particular, might want to boost with what — and a early version of the recommendations suggests that Americans “should” stick with the same brand they got in their first round.

Switching to another shot would be allowed just like approved by the FDA on Wednesday; according to the draft CDC guidelines, folks can choose to mix and match based on availability or preference, after assessing their individual risks and benefits. (As a reminder, FDA approvals tell Americans which vaccines to get. The CDC follows that up with advice on which people should do with those options.)

So the CDC’s stance on mixing and matching could be a relatively soft stance, neither glorification nor fornication. That may also be the most practical course of action for the agency, given the variables involved and the lack of clear evidence that could untangle them. But the slack was from Choose whatever is confusing as hell.

First, take a look at the sheer number of choices now available to booster-eligible Americans (a limited number of mRNA recipients and all people who received J&J). With three approved or authorized vaccines, the simplest mix-and-match matrix has nine possible combos. But that’s an underestimation of the absolutely unmanageable number of variations therein. For example, Moderna’s third shots are coming in full doses for immunocompromised people and half doses for everyone else. The timing of additional injections can also be important: people who receive a second injection of J&J six months after their first injection seem produce more antibodies than people who wait only two months. Obviously, inoculation isn’t just about which vaccines you get. It’s about which vaccines, when, how much, how often, in what order, over and over – an absolute multiverse of choices. Add to that the inevitable differences between individual immune systems, and you begin to imagine the horror of the resulting flowchart. Against that chaotic-evil backdrop, the CDC’s interim preference for homogeneity has a certain appeal — even if it creates a somewhat judgmental juxtaposition between what’s by the book and, essentially, what the misfits could do, if they feel like it. to have.

On the other hand, perhaps what the CDC is saying is quite moot at this point. Millions of people have already been given a boost, some before they even qualified. Now that there are even more choices, “people who care about them are voting with their feet,” Céline Gounder, an infectious disease physician at Bellevue Hospital in New York, told me. Which can in the CDC guidance is easy to grab and run with. For anyone who’s made up their minds in either direction, the agency’s relatively hands-off approach isn’t all that helpful (or hard to ignore).

Boosting multiple vaccines can certainly have benefits. People don’t have to worry about matching brands across different doses; individuals in risk groups may have the flexibility to avoid rare, injection-specific side effects. The strategy could even be: more protective. None of that makes choosing a booster any easier, though. As things stand, the decision requires a small leap of faith, or at least an immunological inference. Data on mixing and matching is still relatively scarce, although the early evidence looks promising. A recent National Institutes of Health study found that switching shots seems to remove the antibodies at least as well as, and in some cases a lot better than, staying with one brand. That seems especially true for the OG J&J crowd: mRNA boosters caused antibody levels to rise, compared to a second serving of J&J. (A caveat: The study was boosted at the full Moderna dose, not the half dose FDA approved for non-immunocompromised people.) If that pattern continues, J&J, already the least popular vaccine in the US, could still be used. more of an underdog.

Thats not sure. Gounder advises caution: The NIH study was small and followed an imperfect proxy for protection in fewer than 500 people over a very limited period of time. Boghuma Kabisen Titanji, an infectious disease physician and researcher at Emory University in Atlanta, is a bit more optimistic, telling me that she finds the mix-and-match data compelling enough to provide the strategy. The trends in the NIH research, she pointed out, resemble well in line with the months by data coming from places like the UK, which took a hybrid approach early on, albeit at original doses and with a different range of brands (Pfizer and AstraZeneca).

Ideally, mixing and matching could blur the brand lines between vaccinated Americans, putting more of us in the same reasonably well protected swimming pool. (Did you get Pfizer or Moderna? J&J? Who cares?) Or it could fragment us into infinite subgroups that are increasingly difficult to compare.

Collecting good data on vaccine responses is becoming increasingly difficult as vaccination becomes more tailor-made. With so many Americans poised to choose their own vaccine adventure…you know, like them can-the differences between regimes can be more difficult to identify. We need that data: Hopefully what we’re learning now will help us design better, safer and more efficient vaccine regimens for generations to come. But as fewer people embark on similar journeys, it may become more difficult to group together. Studies may need to be narrower in scope, or work harder to combine data from different parts of the country. That’s not impossible, Saad Omer, a vaccine expert and epidemiologist at Yale, told me. But it does make things more “challenging”.

Some of this beta-testing vibe goes back to last winter, when experts heatedly debated the benefits of skipping or delaying second doses of the Pfizer and Moderna vaccines. Certain countries, including the UK, have staggered the shots; the US and others stuck to the very small gaps prescribed by trials. The delay was a gamble, as it left people partially protected for longer and sent mixed messages to a frustrated audience. But now it looks economical. Really, we were all guinea pigs – and this massive boost round is setting us up for a discombobulation redux.

We will not all be winners; there must always be someone in the group who does worse. But again, ‘worse’ is always relative. Everyone who plays the booster game is technically already fully vaccinated, giving them an edge over the billions around the world who still aren’t. Titanji pointed out that more Americans got boosters than people have received first doses in Nigeria, a country of about 200 million inhabitants.


Even in the US, getting more first photos with people remains the greater priority-that’s how we are collective contain the coronavirus. But America’s hyper-individualistic approach to the pandemic is once again pushing us all to chart our own course. The government has more or less shrugged its shoulders about encouraging mixing and matching and has given us the following decision: choose the path that seems best to you; go to page 7; hope for the best. Here’s the trick, though: no one knows for sure where this chapter ends. Good luck, I guess.