What Breakthrough Infections Can Tell Us
With 165 million people and counting inoculated in the United States, vaccines have, at long last, tamped the pandemic’s blaze down to a relative smolder in this part of the world. But the protection that vaccines offer is more like a coat of flame retardant than an impenetrable firewall. SARS-CoV-2 can, very rarely, still set up shop in people who are more than two weeks out from their last COVID-19 shot.
These rare breakthroughs, as I’ve written before, are no cause for alarm. For starters, they’re fundamentally different from the infections we dealt with during the pre-mass-vaccination era. The people who experience them are getting less sick, for shorter periods of time; they are harboring less of the coronavirus, and spreading fewer particles to others. Breakthroughs are also expected, even unextraordinary. They will be with us for as long as the coronavirus is—and experts are now grappling with questions about when and how often these cases should be tracked.
Breakthroughs can offer a unique wellspring of data. Ferreting them out will help researchers confirm the effectiveness of COVID-19 vaccines, detect coronavirus that could evade our immune defenses, and estimate when we might need —if we do at all. “The more complete and precise data we have about the pathogen and how it spreads
