By this point in the pandemic, it’s quite clear that adding on more shots can come with big benefits, especially now. Months have passed since many people got their shots, leaving antibody levels relatively low. And the heavily mutated Omicron can hopscotch over several of the antibodies that are left, taking hold more easily in vaccinated bodies compared with its predecessors, and perhaps transmitting more rapidly out of them. But a booster’s bump can skyrocket both the quantity and quality of frontline immune defenses, and restore much of the body’s ability to pin the coronavirus in place. Early data suggest that while two doses of an mRNA vaccine deliver kind of meh protection against Omicron infection, tacking on another dose brings the body back to a Delta-like benchmark. Omicron will still spread within vaccinated bodies, and among them. But it will do so less often with a booster. At this point, “I don’t think we can meaningfully interrupt transmission without three doses,” Saad Omer, a Yale epidemiologist, told me. Our viral opponent has clearly upped its offense, and boosters—a bolstering of defense—have never made more sense.
Looping boosters into “full vaccination,” then, could clinch the importance of these shots. “We’ve hit a tipping point,” Jason Schwartz, a vaccine-policy expert at Yale, told me. It’s become essential to “encourage and promote boosters,” and sticking stubbornly to a now-obsolete definition of 'fully vaccinated' could undermine that effort.
A modification wouldn’t be without precedent. The measles/mumps/rubella vaccine first debuted as a single shot, but it became a double-doser in 1989 to better contain outbreaks; the chicken-pox vaccine underwent a similar tweak in 2006 ...
... [Experts] like Grace Lee, a Stanford pediatrician and the chair of the CDC’s Advisory Committee on Immunization Practices, thinks we might be better off shifting the conversation entirely—asking whether people are “up-to-date” on their shots, rather than whether they’re fully vaccinated. Whereas 'fully vaccinated' implies a sort of finality, and has, to some, even become shorthand for fully protected, 'up-to-date' is more flexible and forgiving. The phrase, which is already used among health professionals when discussing vaccines, might leave more room for individual tailoring, and it accommodates the unpredictability of our circumstances. 'Up-to-date' is also a little more agnostic on the primary-versus-booster distinction. And asking “Did you get your shot this year?” rather than “Are you fully vaccinated?” could be an especially useful framework, Lee told me, if we end up having to retool and readminister our vaccines somewhat regularly, much like we do with vaccines for the seasonal flu.