The coronavirus situation in the United States continues to escalate with the country’s case total well over 550 and over 30 states reporting cases as of Monday. There have been 22 deaths.

Cases in the United States rose fivefold just over last week. But it’s important to keep in mind that these aren’t necessarily new cases. The boom in disease detection stems from ramped-up testing by state and local health departments in the past week, revealing a backlog of cases that in some places may have been spreading quietly for weeks.

The slowed access to tests has hobbled the country’s response to the virus. The US Centers for Disease Control and Prevention developed a test for the coronavirus early last month, but the test quickly ran into technical problems that the agency was slow to resolve. Those technical issues are now worked out, federal regulators have relaxed rules on who can develop additional tests, and commercial test kits are coming on line. Still, the US is struggling to meet testing demands as the disease has continued to spread and more people have potentially been exposed.