You’re Not Fully Vaccinated the Day of Your Last Dose

Patience, grasshopper.

For much of 2020, the world pinned its collective post-pandemic plans to a single, glimmering end point: the arrival of an effective COVID-19 vaccine. The resounding refrain of “when I’m vaccinated” has long conjured images of people shedding their masks, hugging their friends, and returning to a semblance of normalcy. And now some vaccinated people are doing exactly that. In recent weeks, I’ve heard dozens of stories from friends, family members, and co-workers about vaccinees who are immediately dropping their guards after their shots, in some cases discarding their masks and congregating with others. Deepta Bhattacharya, an immunologist at the University of Arizona, told me that one of his colleagues—another biologist—went out to a celebratory dinner right after getting a dose at a 24-hour clinic.

But immunity to the coronavirus doesn’t just magically manifest the day someone gets a shot. The CDC does not grant membership to the “fully vaccinated” club until at least two weeks after the final dose in a vaccine regimen—a time that roughly corresponds to when most people are thought to acquire enough immunity to defend against a symptomatic case of COVID-19. Only then, the agency announced last week, can vaccinees start to carefully change their behavior, mingling maskless in small groups indoors, visiting the unvaccinated on a limited basis, and skipping postexposure quarantines.


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