Last summer, at the Centers for Disease Control and Prevention, an internal presentation on the coronavirus, which was leaked to the press, called the Delta variant of COVID-19 “as transmissible as chicken pox.” Although the claim was found to be overstated, it’s easy to see why researchers may have been predisposed to draw parallels between the two diseases. Both varicella-zoster—the proper name for the chicken-pox virus—and the coronavirus are spread through the air, and both can be contagious before any symptoms are evident. Both have relatively mild impacts on most children, with a higher risk of more serious effects in adults. The mostly apocryphal tales of “COVID parties”—which almost always turn out to be unintentional spreader events—descend from those of “chicken-pox parties,” where parents knowingly exposed their children to symptomatic peers.
There was also a kind of wistfulness in the comparison. A vaccine for varicella received full approval from the Food and Drug Administration in 1995, and within a decade forty states and the District of Columbia added varicella as a required immunization for enrollment in public elementary schools. Today all fifty states enforce this mandate. (Medical and religious exemptions vary state by state.) Near-universal mandatory immunization against chicken pox virtually eliminated the disease in the space of a generation.