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

Medical professional wearing scrubs, gloves, goggles, surgical mask, and shield, with a syringe.
The Atlantic
This is true of all vaccines: Their protective effects take several days or weeks to kick in. It’s the reason we get our flu shots in the fall, well before the height of respiratory-virus season, and it’s why health officials often recommend that vaccines required for travel, such as those that ward off yellow fever, be administered about a month or more in advance. Vaccination, and the defenses it affords, is less a singular event than a series of steps on a shifting landscape.