Public health experts called for more testing to provide a clearer picture of the magnitude of the pandemic and to identify, isolate and track contacts for infected patients.

High rates of positive results could mean that there are not enough tests, Fauci said, adding that they should be “maybe less than 10 percent”. In the US, positive rates are currently close to 20 percent.

Adequate testing should “remove those who are infected from society so that they do not infect others,” he said.

Fauci warned public health groups not to fix the number of tests required. What is more important is whether “you have enough tests to respond to the outbreaks that will inevitably occur if you try to ease the way back through the different phases,” he said.

Rapid expansion of testing could be hampered by supply chain challenges and requires careful national coordination, as POLITICO reported.

Fauci emphasized that his comments relate to the diagnosis of active infections and not to the antibody tests, which can reflect whether a patient was previously infected with the virus.

The US has seen more than 915,500 cases and over 51,600 deaths, Fauci noted during the webcast.