“we” as used collectively, for instance, to denote the USA, ‘we’ can beat the Brits’ or the capability of the USA testing sites collectively, ‘we can test 1/2 million’ as in this case.
1/2 million tests and 1/2 million positives in one day...something does not equate. All positives?
“The good news is, we actually can test 1/2 a million in a day”
As sjeann points out, 1/2 million positives means many more total tests (five or ten times as many, with test positivity rates now surging to around 10-20% in different places).
At some point (probably soon) this explosive growth in infections might (likely, at least locally) exceed testing capacity, and an increasing percentage of infections will go unconfirmed/unreported.
When reported new case growth does top out, we will need to consider if the infections have actually crested, or if the capacity of testing to record them has been reached.
Test positivity rate increases might be an early indicator of that, while hospitalization or death rate increases might be trailing indicators.