COVID-19 tests are flying off store shelves. What’s driving the demand?

It’s the critical aspect of the fight against the pandemic that the U.S. is still figuring out nearly two years after the first documented cases of COVID-19, which has claimed more than 700,000 American lives: coronavirus testing.

At first, testing supply was extremely limited with long lab turnaround times, and only a handful of Americans could access them before things improved as tests became more widely available. Then suddenly, testing demand dropped as mass vaccinations began.

Now, despite billions of dollars in federal investment and more than 20 months into the pandemic, COVID-19 tests are getting harder to find as millions return to offices and schools.

The struggle to keep up with demand also comes amid shifting federal guidance on who should be tested and when as some companies and schools conduct extensive testing, even in situations that may not require it.