Q:
I am planning a trip to Europe this summer. To come back to the United States, I’ll have to test negative for COVID-19. I am fully vaccinated (Pfizer-BioNTech) and have had my booster shot, but could I still get COVID? I don’t want to be quarantined overseas.
A:
This is an excellent question. While your three doses of the Pfizer-
BioNTech vaccine do markedly diminish your risk of suffering a severe bout of COVID-19, they don’t protect you as much from contracting the disease and thus from posting a positive COVID test requiring quarantine.
Remember that the primary public health benefit of the various COVID shots developed around the world has been to mitigate the severity of disease if someone does catch COVID-19, which they do quite well for a period after the initial shots (around six months for the delta variant, for example, after which a booster is recommended). This is important, among other things, for reducing the disease and treatment burden on already overstressed and understaffed hospitals and clinics. However, the jabs don’t provide much in the way of mucosal immunity, which is to say they don’t stop you from actually catching and transmitting COVID.This is an excellent question. While your three doses of the Pfizer-
BioNTech vaccine do markedly diminish your risk of suffering a severe bout of COVID-19, they don’t protect you as much from contracting the disease and thus from posting a positive COVID test requiring quarantine.
Outbreaks of the delta variant in Provincetown, Mass., and the University
of California hospital system in the summer of 2021occurred largely among vaccinated patients. The vaccines limited how sick people got, but did not, ultimately, stop the local hotspots from happening or the coronavirus particles from spreading.
The transmission danger is even worse with omicron, which is still more contagious than the delta variant. While there is some evidence that the vaccines do contribute somewhat to reducing person-to-person dissemination, the effect is quite limited.
Thus the upshot is that, with your two-dose initial COVID-19 vaccine series and booster shot, you’re likely to be well-protected against severe illness from omicron (currently the dominant variant) or from delta or other strains. However, if you’re in an area with high COVID prevalence on your trip, there’s still a significant chance you might contract COVID and test positive on your return leg to the United States, necessitating a period of quarantine.
There’s no perfect way to insulate against this risk, but as before, try to mask up as much as possible, social distance when you can, and seek out outdoor events (or indoor outings with good ventilation) to minimize the potential for spread. And if you can, try to find venues or events where people are tested beforehand.
