The Differences Between the Vaccines Matter

Hilda Bastian, The Atlantic: March 7, 2021


Public-health officials are enthusiastic about the new, single-shot COVID-19 vaccine from Johnson & Johnson, despite its having a somewhat lower efficacy at preventing symptomatic illness than other available options. Although clinical-trial data peg that rate at 72 percent in the United States, compared with 94 and 95 percent for the Moderna and Pfizer-BioNTech vaccines, many experts say we shouldn’t fixate on those numbers. Much more germane, they say, is the fact that the Johnson & Johnson shot, like the other two, is essentially perfect when it comes to preventing the gravest outcomes. “I’m super-pumped about this,” Virginia’s vaccine coordinator told The New York Times last weekend. “A hundred percent efficacy against deaths and hospitalizations? That’s all I need to hear.”

The same glowing message—that the COVID-19 vaccines are all equivalent, at least where it really counts—has been getting public-health officials and pundits super-pumped for weeks now. Its potential value for promoting vaccination couldn’t be more clear: We’ll all be better off, and this nightmare will be over sooner, if people know that the best vaccine of all is whichever one they can get the soonest. With that in mind, Vox has urged its readers to attend to “the most important vaccine statistic”—the fact that “there have been zero cases of hospitalization or death in clinical trials for all of these vaccines.” The physician and CNN medical analyst Leana Wen also made a point of noting that “all of the vaccines are essentially a hundred percent” in this regard. And half a dozen former members of President Joe Biden’s COVID-19 Advisory Board wrote in USA Today, “Varying ‘effectiveness’ rates miss the most important point: The vaccines were all 100% effective in the vaccine trials in stopping hospitalizations and death.”

There’s a problem here. It’s certainly true that all three of the FDA-authorized vaccines are very good—amazing, even—at protecting people’s health. No one should refrain from seeking vaccination on the theory that any might be second-rate. But it’s also true that the COVID-19 vaccines aren’t all the same: Some are more effective than others at preventing illness, for example; some cause fewer adverse reactions; some are more convenient; some were made using more familiar methods and technologies. As for the claim that the vaccines have proved perfectly and equally effective at preventing hospitalization and death? It’s just not right.

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The data were indeed suggestive of an encouraging idea. Based on the numbers so far, we can expect the vaccines to provide extremely high levels of protection against the most dire outcomes. Still, we don’t know how high—and it’s clear they won’t uniformly cause hospitalizations and deaths from COVID-19 to disappear in vaccinated people.

The experts understand this, of course. Gandhi has been updating her table as more data come in, and now pegs Moderna’s efficacy on that front at 97 percent; Jha has since tweeted that “nothing is 100 percent … But these vaccines sure are close”; and Topol told The Atlantic that the numbers in his tweet are not a sufficient basis from which to draw “any determination of magnitude of effect,” though the fact that they all point in the same direction is “very encouraging.” Still, the message of perfection that their initial tables and tweets spawned—the gist, for many readers, of all those 100s and zeros—has since been picked up far and wide, and misinterpreted along the way.

For the AstraZeneca vaccine, one person in the control group had severe COVID-19, but eight people were hospitalized; for Johnson & Johnson, 34 people in the placebo group had severe COVID-19, but only five people were hospitalized. It’s true that zero vaccinated people were hospitalized in either study after the vaccines took effect. But with numbers that small, you can’t draw a reliable conclusion about how high efficacy may be for these outcomes. As Diana Zuckerman of the National Center for Health Research pointed out about the Johnson & Johnson trial, “It’s misleading to tell the public that nobody who was vaccinated was hospitalized unless you also tell them that only 5 people in the placebo group were hospitalized.” She’s right. And you can’t be confident about predicting effectiveness precisely in a wider population outside the trial, either. For example, some of the vaccine trials included relatively few people older than 60 as participants.

You can see how fragile these numbers are by looking at those compiled for severe disease. In the Pfizer trial, for example, just one vaccinated person developed severe COVID-19 versus three in the placebo group—which meant that a single bout of disease made the difference between a calculated efficacy rate of 66 percent and one of 100 percent. For the Novavax and Oxford-AstraZeneca trials, there were zero people with severe disease in the vaccinated group versus only one in the control group, so adding or subtracting one would have been even more dramatic. The problem is even greater for deaths. For that efficacy analysis, only two of the vaccine trials—for Moderna’s and Johnson & Johnson’s—reported any COVID-19 deaths at all in the control groups.

It’s also important to remember that these are early results: Some people who enrolled very late in the trials aren’t yet included in reported data, and analysis is still under way. Indeed, the FDA pointed out in December that one vaccinated person in the Moderna trial had been hospitalized with apparently severe COVID-19 two months after receiving a second dose. That person was in a group still awaiting final assessment by the researchers, and was not mentioned in Moderna’s formal readout of results.

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“The idea that people can’t handle nuance,” Jha tweeted at the end of February, “it’s paternalistic. And untrue.” I couldn’t agree more. The principle of treating people like adults is fundamental. We don’t need to exaggerate. Talking about the trade-offs between different medicines and vaccines is often complicated, but we do it all the time—and we can do it with COVID-19 vaccines too.

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