This fall, Schwartz and Paltiel, along with Rochelle Walensky, who’s now the head of the Centers for Disease Control and Prevention, looked more closely at the question of which would save more lives: a highly effective two-dose vaccine, like those from Moderna and Pfizer, or one that’s less effective but easier to get into people’s arms, like J&J’s. Effectiveness versus efficiency. They designed a simple model that projected the number of potential deaths and hospitalizations into the spring, based on the pandemic’s dire state, and compared how well various theoretical shots would prevent them. For the most effective two-dose vaccine, they started with an efficacy of 75 percent. “We thought that was the best we could possibly hope for,” Schwartz says. (When the Pfizer and Moderna results arrived, the team had to quickly rerun their numbers.)
Even with the two-dose vaccine bumped up to 95 percent efficacy, their model suggested that efficiency remained key. A 55 percent effective single-shot vaccine could prevent just as many deaths, they found, as long as a lot of people could get that shot quickly. Hence the team’s excitement over adding the J&J results, Schwartz says. It requires half as many doses—which means half the shipments, the sign-ups, the staff time, the headaches—to get the same number of people protected. And, unlike in his team’s simulation, the US is getting both kinds of vaccines, not just one or the other, meaning more deaths can be avoided.
Still—and here we’ll stop evading the question—having all those options means states will need to decide where doses of each go. There are no guidelines yet for where vaccines will be sent, and Schwartz thinks many states will opt to keep it that way: The feds will send a batch of vaccines out, and they’ll go to whichever provider—whether that’s a pharmacy or doctor’s office or mass clinic—needs them. In other words, distribution will be first-come, first-serve and fairly random. But other states may see an opportunity to prioritize certain vaccines for certain people. They could try to reserve the mRNA vaccines for the people most at risk from severe illness, given the slight boost in protection. Or they might choose to nudge the J&J vaccine to certain areas—say, rural communities with less medical infrastructure—because of its logistical ease.
Yet Ann Lewandowski, a program manager at the Rural Wisconsin Health Cooperative, says that doesn’t square with the challenges of the vaccine distribution effort so far. The logistical snafus particular to the mRNA vaccines, like freezer space, have been far less an issue than ensuring an adequate and predictable supply—enough for their patients, but not so much in one batch that they’re overwhelmed. (One way J&J could help is by sending out smaller, more flexible orders appropriate for small clinics, Lewandowski says. The company didn’t respond to an inquiry asking about its expected minimum order size.) In any case, she agrees with Fauci: The biggest need is delivering more shots.
There are some situations where she could see a single-shot vaccine being particularly useful. One might be for instances in which second doses are particularly hard to arrange: for example, at a pop-up clinic that serves unhoused people. Lewandowski has a relative without a permanent address or doctor, and she knows how difficult it can be to get people in those situations back for a second dose. “I’m a realist,” she says. “My personal experience is with somebody who is hard to track down.” But when she floated the idea in a Facebook group where health workers were discussing the J&J results, she got pushback. Another health official argued that giving a less effective vaccine to vulnerable people was akin to “giving up” on finding them again for second doses, relegating them to an inferior product.