The number of coronavirus diagnostic tests being completed every day has plateaued over the last week — at a number that falls far short of what experts say is needed.

Between the lines: Some states are testing more than others, but we’ve got a long way to go before we’re ready to safely resume normal life. Otherwise, the virus will easily be able to spread undetected.

Ashish Jha, director of the Harvard Global Health Institute, said he thinks we need to be doing 500,000 tests a day for the foreseeable future.

Nationwide testing capacity steadily increased for weeks, but has appeared to hit a wall around 145,000 tests a day. Several factors are holding it back:

Supply shortages for key test ingredients, swabs, test kits, and personal protective equipment.

for key test ingredients, swabs, test kits, and personal protective equipment. Poor coordination: Some labs have excess testing capacity, but aren’t being sent samples from the providers collecting them.

Some labs have excess testing capacity, but aren’t being sent samples from the providers collecting them. Rules about who gets tested: Many states have limited testing to the sickest patients, and caseloads are dropping overall. But clinicians often have discretion as to who they test.

Data: The COVID Tracking Project, U.S. Census Bureau; Cartogram: Andrew Witherspoon/Axios

Variation among states isn’t only a result of demand. For example, Michigan is a hotspot for cases, but is near the bottom of the pack in testing.