Home COVID-19 tests make it impossible to track all cases because vast majority are not reported.

Thousands of people traveling for the holidays this week will first test themselves for COVID-19 without a doctor, lab or any medical oversight.

While these quick home tests are hailed as a major convenience and a smart way to protect loved ones, they’ve also raised a significant challenge for public health officials. How can agencies comprehensively track cases and trends when many consumers don’t report home test results?

Federal and state health officials have worked since March 2020 to build capacity to test, report and keep tabs on COVID-19 cases. Public health officials say reporting cases is critical for spotting trends and detecting surges so hotspot communities can lessen risk and prepare hospitals for a rush of people seeking care.

But it's unclear how often customers report results from the dozen authorized home coronavirus tests that typically deliver results in 15 minutes outside a lab or doctor’s office. And public health's data blind spot is poised to grow larger. Private test manufacturers already make more home antigen tests than standard laboratory tests — and the gap could nearly double next month as new home tests flood the market.

“The whole issue of us tracking every single case is just not going to be possible anymore with these (home) tests,” said Marcus Plescia, chief medical officer of the Association of State and Territorial Health Officials. “We need to move to a different approach.” ...