Everyone should do what they can to free testing resources for those with symptoms. We should also try to allocate tests based on underlying risks. The unvaccinated are, overall, most in danger of being hospitalized and dying from the virus, so they are also, overall, the people who benefit the most from having those around them screened for infection. Social bubbles being what they are, I suspect that many people with arsenals of at-home tests spend much of their personal time around other vaccinated and relatively low-risk individuals, making the public-health benefits of their personal screening programs marginal at best.

Two major categories of people remain at serious risk of dying from COVID despite vaccination: the elderly and immunocompromised. Older people and those with severe immune-system deficiencies will quite reasonably take extra precautions while socializing—including asking their close contacts to make prodigious use of rapid tests. Outside of nursing homes, though, there has been little effort in the U.S. to prioritize diagnostic access for these groups. Instead, we face an awkward situation where many universities are performing thousands of tests a day on young, vaccinated, and largely healthy student populations while high-risk individuals and their caregivers struggle to keep up with surveillance. Well-heeled companies like Google are even sending employees—many of whom are still working from home—some of the most sophisticated COVID-detection tools on the market. “The worried, wealthy well are doing lots of tests of uncertain value,” the epidemiologist Daniel Morgan of the University of Maryland told me, while “the turnaround time is blowing up for higher-value uses.”