But after this population, deciding who’s next in line arguably becomes even more complicated. One reason for that is while the first vaccines appear to at least stop most people from developing severe disease, we do not yet know if they stop people from spreading the virus — a key secondary benefit that, while possible and perhaps even likely, is not assured.
If the vaccine does block transmission, some epidemiologists have suggested, the middle phase of the vaccination drive should prioritize younger adults because they pose a higher risk of spreading the virus. A similar logic has been applied to flu vaccinations since 2009, when epidemiologists showed that better protection against the swine flu could have been achieved by vaccinating those most likely to transmit it instead of just those most vulnerable.
With the coronavirus, “college students and young adults are significant transmitters and also less likely to suffer complications,” Kim Tingley writes in The Times Magazine. “Given these dynamics, if a future vaccine proves to be effective for all ages and is widely available, saving the most lives could mean prioritizing the vaccination of children and young adults — even though they’re among those Covid is least likely to harm.”
Yet many researchers are wary of taking that gamble as long as the vaccines’ transmission-blocking abilities remain unknown. “Let’s forget about protecting the masses to protect the vulnerable,” Dr. Eleanor Riley, a professor of immunology and infectious disease at the University of Edinburgh, told Reuters. “Let’s directly protect the vulnerable.”
The National Academies seems to be taking that tack: In its framework, third priority is allocated equally to older adults, essential workers and people in homeless shelters, jails and prisons, leaving healthy young adults and children last.
What makes a vaccine rollout ‘optimal’?
Much of the discussion around vaccine priority has focused on minimizing the number of Covid-19 deaths and cases, but those will not be the only two factors in play. Dr. Anthony S. Fauci, the nation’s top infectious disease expert, said on NPR in November that the priority list will be graded according not only to risk but to the degree to which certain people, like teachers and child-care providers, are deemed “important to society.”
How one measures importance to society is, of course, a very thorny question. The National Academies framework, for its part, suggests that people should have higher priority “to the extent that societal function and other individuals’ lives and livelihood depend on them directly and would be imperiled if they fell ill.” In other words, economic and quality of life concerns will be part of the equation.