Philadelphia has reassigned the van providing mobile COVID-19 vaccination services, saying that flexible, fast testing is now the more urgent need.

Demand for testing is overwhelming providers in some parts of the city, said James Garrow, a spokesperson for the Philadelphia Department of Public Health.

“This was the quickest way to surge testing capacity in typically underserved areas that may not have access to regular walk-up testing,” he said.

The city’s decision to prioritize mobile testing happened in early fall, long before President Joe Biden on Thursday declared testing to be key in responding to the omicron variant’s spread worldwide. The president announced 150 million Americans with private insurance will have the cost of at-home testing kits covered by their insurer. The White House also plans to provide 50 million free tests to community clinics, including those in rural areas.

Though they are cheap in many countries, the U.S. kits cost close to $25 in some places, and even at that price can be hard to find.

“We are extremely excited about the White House’s plans,” Garrow said. “Testing, especially access to rapid at-home testing, is a big gap all across the country.”

The dearth of cheap, accessible at-home options has helped drive demand for tests at clinics, hospitals, and pharmacies, he said, as gold-standard PCR and rapid tests are sought by people who just want to ensure they don’t have COVID-19, or have symptoms like a cough, which could be caused by myriad illnesses.

“With more rapid at-home tests kits available,” Garrow said, “we can hopefully relieve the burden of people who are almost definitely not infected from those testing sites.”

The city’s mobile vaccination van was administering just 18 to 20 doses a week by the end of September, Garrow said, half of what it had administered in late August. Meanwhile, he said, vaccines had become easily available at hundreds of sites citywide. Typically, the van was assigned to churches or community facilities in undervaccinated neighborhoods.

The city has needed more testing resources since the beginning of the pandemic, but demand surged over the summer as the delta variant spread, leaving people struggling to book appointments for testing. At-home testing kits became scarce too.

» READ MORE: More people are getting COVID-19 tests around Philly as delta spreads and worry rises

Currently, from all test sources in the city, the health department receives 7,200 to 8,500 test results daily, and up to 300 of them are positive.

The van is assigned based on a neighborhood’s case count and positivity rate, and is typically adjacent to a community gathering site like a church, ideally one with parking. The van stays in place for a month, and then the need for it elsewhere is assessed.

Though it’s hard to get tested, city health officials believe the test results they are receiving still manage to reflect COVID-19′s prevalence. The city’s positivity rate was 4.8% as of last week, just shy of the 5% mark, which would indicate that testing is inadequate to accurately show how much the virus has spread, Garrow said.