The U.S. government will send an "overwhelming majority" of the rapid COVID-19 tests it purchased from Abbott Laboratories last week to governors of states and territories to support school reopenings and other critical tasks, an administration official said at a press briefing.

Other top priorities for the newly purchased tests include daycare centers, first responders, and "critical infrastructure," said Admiral Brett Giroir, assistant secretary for health at the U.S. Department of Health and Human Services.

The tests will be distributed in collaboration with Abbott beginning in mid-September, Giroir said. Abbott said last week it will ramp up production to around 50 million tests per month by mid-October.

The U.S. government agreed to purchase 150 million rapid antigen tests for COVID-19 from Abbott in a roughly $750 million deal.

The portable tests can deliver results within 15 minutes and will sell for $5. They require no additional equipment and can use a less invasive nasal swab than traditional lab tests.

Antigen tests are cheaper and faster than molecular diagnostic tests, but somewhat more likely to fail to identify positive cases of the virus than lab-based diagnostic tests.

President Donald Trump has repeatedly pushed for schools to reopen, but most of the largest U.S. school districts have said they would start the school year with online classes.

Giroir also said the Centers for Disease Control and Prevention (CDC) still supports testing asymptomatic individuals for COVID-19 who are prioritized by local health officials or in high-risk populations. Last week, the CDC sparked an outcry among many public health officials when it said testing some asymptomatic people may not be necessary.

The United States has conducted 85 million COVID-19 tests so far with a positivity rate of just over 5%, Giroir said. The mean turnaround time is 2.27 days.