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Which is better: Pfizer or Moderna? Andy Larsen dives into the data with boosters looming.

This much is clear: Any of the approved vaccines is effective and far better than no shot at all.

(Trent Nelson | The Salt Lake Tribune) Lindsay Brown prepares a dose of the Pfizer COVID-19 vaccine at a drive-thru event organized by the Utah County Health Department in Spanish Fork on Friday, Sept. 10, 2021.

We’re all tired of the arguing over the coronavirus vaccine, but here’s one debate topic you probably haven’t thought about:

Who should win the Nobel Prize for its development?

That’s the focus of an article in Nature magazine, which showed up on newsstands Thursday. It’s pretty clearly the most important medical innovation in years, maybe decades, but deciding which of the hundreds of scientists in various labs who worked hard on the project deserve recognition is difficult to decide. After all, progress in science isn’t straightforward, but labyrinthian.

While that frustrates some, and gives fuel to science deniers, it’s also reality. And we’ve seen it in the research in recent weeks, fueled by nature (not the good people at Nature) throwing us the delta variant curveball. We undoubtedly know more than we did a month or two ago, but the path forward isn’t always clear.

Still, you deserve to know where the research stands. Here’s what’s going on:

Is Moderna better than Pfizer?

You may remember my original article in March comparing the vaccines, in terms of efficacy and side effects in various benchmarks. Back then, it was definitely a close race between the two vaccines, but it appeared that Pfizer had the slightest of edges in efficacy and a slightly less large chance of minor side effects. (It’s worth noting that the differences were pretty minuscule, probably within the margin of error.)

But we’ve gotten a couple of studies since then that use real-world data to show a gap has arisen between the two vaccines over time. One comes from Qatar, which found approximately equal rates of protection between the two vaccines when someone had been previously infected before getting the vaccine — but unequal rates of protection when someone hadn’t been previously infected.

Note that 11 cases per 10,000 person weeks is still a small number compared to the rate of cases among the unvaccinated — it’s not that the Pfizer vaccine doesn’t provide any protection! New research this week from the United Kingdom estimates its efficacy against symptomatic infection is about 75%, 20 weeks after the second dose.

Those who studied the Qatar data, though, noted a potential flaw: Moderna was approved after Pfizer in that country, and so, naturally, was injected into people a little later. That might explain some of the big gap.

A Mayo Clinic study looked at about 50,000 people from Minnesota in studying the same issue — and it took care to take into account the time people were vaccinated as a potential confounding variable. Researchers found that, over the course of the study, Pfizer had 76% efficacy against infection, while Moderna had 86% efficacy.

Why would there be a difference? The Pfizer and Moderna vaccines use basically similar mRNA sequences in their formulation, but their delivery is a bit different: The Pfizer vaccine used 30 micrograms, while the Moderna vaccine used 100 micrograms. Moderna suggested four weeks between shots, while Pfizer recommended three. Did this cause differences? Some still would like to see more data on the issue, but early evidence points that way.

Big decisions on boosters

Just because Moderna is performing better than Pfizer in these early studies doesn’t mean Moderna’s vaccine also hasn’t fallen somewhat in effectiveness. In a news release sent Wednesday, Moderna followed up with those participants from its original study and found that those vaccinated eight months ago had 36% fewer cases than those vaccinated 13 months ago. Just like Pfizer — I laid out Pfizer’s case for needing a booster shot in August — Moderna is using this as evidence for booster shots needed for Moderna-inoculated folks.

The case is more obvious for Pfizer’s vaccine, which found a 19.5-fold reduction in those 60 and over people experiencing severe illness after getting the third dose in Israel. That’s with a huge, countrywide dataset; with Moderna’s vaccine, the only data we have is 344 people who volunteered to get the third dose. Given the widespread similarities between the vaccines, it would make sense that a third Moderna dose would boost efficacy but by how much? Is it worth it?

While we’re at it, there are some other relevant questions we’d like to answer.

• There’s some data from the U.K. that the people who are best protected got one dose of the Pfizer vaccine and one dose of the AstraZeneca inactivated-virus vaccine — the different types of vaccine seem to give the immune system a better picture of what to look out for. Should we do that in the U.S., but with Johnson & Johnson’s inactivated-virus vaccine standing in for AstraZeneca’s (which hasn’t been approved in the states)?

• Or, heck, if Moderna’s vaccine (or delivery of it) really is better, should we make everyone’s booster shot Moderna? Should we use a larger dose of Pfizer?

• Given that the delta variant is well over 90% of cases in the U.S., should the booster shots be formulated specifically for it?

• Which is better for Americans? Getting booster shots for people who have already been vaccinated, or sharing the vaccine with the rest of the world’s population, lowering the likelihood of further variant evolution?

These are tough questions. Members of the Advisory Committee on Immunization Practices — the advisory board to the Centers for Disease Control and Prevention — is meeting for 10 hours Tuesday and Wednesday about these issues. There, they will take in all of the data and likely make a recommendation to the CDC, which the CDC is likely to quickly accept.

I’m relatively sure they’ll recommend a booster shot for Pfizer recipients over 60. The data is quite strong in the favor of that move preventing significant hospitalization. Beyond that, though, I’m uncomfortable predicting what the panel will do.

Blood-clot comparison

One risk of the above reasonable pondering is paralysis by analysis. Rather than doing a good thing, sometimes we can spend too long examining a situation looking for a perfect solution. Inaction is also a choice.

Some who haven’t gotten the COVID-19 vaccine are subject to this. They say they’re waiting for more data, or Food and Drug Administration approval, or for a year to pass, or whatever, before they say they’ll make their move. Some have cited the risk of serious side effects, like blood clots, as a reason they’re not getting vaccinated.

But here’s the thing: COVID-19 infection also has serious risks of blood clots. A study published in the British Medical Journal compared blood-clot outcomes for those who got vaccinated with the two vaccines compared to those who were infected. They also made a handy-dandy graphic for anyone looking to share the results (something more study authors should consider doing).

A visual abstract from the British Medical Journal of how much more common blood clots are among COVID cases than vaccine recipients. (https://www.ox.ac.uk/news/2021-08-27-covid-19-not-vaccination-presents-biggest-blood-clot-risks)

The pink dots are all quite to the right of the orange and purple dots? That means that the risk of blood clotting — in your arteries, veins, brain, heart, you name it — are all substantially greater among those who were infected than those who were vaccinated.

Of course, blood clots aren’t the only bad thing that can occur from COVID-19 infection. This study didn’t look at the much more common results of getting infected, like lung failure, shortness of breath, fatigue, joint pain, mental issues, and so on.

So, yes, we have some decisions to make to try to optimize COVID vaccination. But getting vaccinated in general? Definitely a good idea and needs to be priority No. 1.

Andy Larsen is The Salt Lake Tribune’s data columnist. You can reach him at alarsen@sltrib.com.

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