One of the first people to address the committee was Santa Claus. Or, more precisely, it was Ric Erwin, chairman of the board of the Fraternal Order of Real Bearded Santas. The committee members didn’t quite take him seriously (one confessed that he had never stopped believing in Santa), but Erwin had come in earnest. “This year, Christmas will be more important to the American psyche than ever before,” he said. It was vital that the country have a cadre of vaccinated Santas ready to safely hear the wish lists of children everywhere. “We’re asking that professional Santas and other frontline seasonal workers be granted early access to the Covid-19 vaccine as soon as practical after tier-one release.”
Erwin had done his homework: The vaccine will be released in tiers, or phases. The earliest doses, perhaps as many as 20 million, will go to the groups deemed most essential by the CDC committee, according to a prioritization scheme that has not yet been finalized. After that, larger and larger groups of Americans will be granted permission to be vaccinated, until everyone is covered. Erwin wanted the Santas as close to the top of the list as possible, though his December deadline would be hard to meet.
In considering whom to prioritize for the vaccine, the committee highlighted some of the difficulties in getting it out to the public once it is approved. First, both the Pfizer and Moderna vaccines will require at least one booster shot, so the number of people who can be inoculated is half of the number of total doses available. The Pfizer vaccine will also need to be kept at -94 degrees Fahrenheit during transport and storage—quite a lot colder than most of the other shots in doctors’ freezers.
Then there is the risk that large portions of the country will refuse to be vaccinated. During the Salk vaccine trials of 1954, when hundreds of thousands of schoolchildren were inoculated against polio, the parental consent form was edited to change “I give my permission” to “I hereby request”; the implied scarcity was intended as an extra nudge to anxious parents. For Covid, there will be plenty of scarcity to go around (so to speak), but persuading the public to commit to being vaccinated is far from assured, and it gets less likely with every blusterous statement from the White House. (As Senator Kamala Harris said at the vice presidential debate in October, “If the doctors tell us that we should take it, then I’ll be the first in line to take it—absolutely. But if Donald Trump tells us that we should take it, I’m not taking it.”)
Each of these obstacles was a stubborn reminder of the way that the real world might not match a network scientist’s computer model. Acquaintance immunization is simple in theory, but what happens if the acquaintance is an antivaxxer? Or if her town doesn’t have the ability to keep the vaccine’s cold chain intact? Or if she’s so busy being the life of the party that she forgets to show up for her booster shot?
Even if a targeted strategy works as designed, it can lead to outcomes that feel morally questionable. Let’s say you’ve got one course of the vaccine and two people to choose between: Candidate 1 is a college student who doesn’t social distance, wears his mask slung beneath his chin, and plays beer pong all weekend at underground frat parties. Candidate 2 is his 87-year-old widowed grandmother, who lives on her own and has barely been out of the house since March. If your goal is to protect the more vulnerable person, you should vaccinate grandma. If your goal is to reduce transmission, you should vaccinate the frat bro. From society’s perspective, he’s a jerk; from the network’s, he’s a hub.
The prioritization committee seemed to be making a similar sort of utilitarian calculus. Rachel Slayton, a CDC epidemiologist who heads the committee’s data, analytics, and modeling task force, talked about the benefits of vaccinating the staff of a nursing home rather than its residents. “Because older adults have lower numbers of contacts,” she said, “the impact on the broader community of vaccinating the residents I would expect would be relatively small.” The best approach for the community would be to target the nodes. That should keep the virus out of the nursing homes, but it would also require a counterintuitive decision: Don’t vaccinate the people most likely to die of Covid-19.
Marc Lipsitch, an epidemiologist at Harvard’s School of Public Health, says the CDC committee is grappling with a fundamental question. “Essentially there are two approaches to using a vaccine,” he says. “One is to protect individuals by vaccinating them, and the other is to reduce transmission and therefore protect the population.” Although the committee would not make any formal recommendations until Pfizer and Moderna released their results, it seemed to be settling, cautiously, on an approach that would attempt to disrupt transmission. Under a plan presented in September, the very first doses would be reserved for health care workers, a population the committee estimates at 17 to 20 million. (The World Heath Organization has made a similar recommendation for its member countries.)