COVID testing drop casts doubt on lower case count

Testing for the coronavirus that causes COVID-19 has dropped nationwide the past two weeks even as the evidence builds disease spread is picking up in many states.

Nowhere is the danger of the testing slowdown more evident than the South. In Mississippi, more than one in five tested for the virus in the past week were positive, the highest rate in the nation as of Friday. The average number of daily tests in Texas and Florida dropped, but the ratio of positive tests in each state is more than double what the World Health Organization recommends.

Official case counts have dropped nationally but reporting problems and generally reduced testing in some states makes it hard to place any confidence that infection rates are improving. And in some states with more reliable data, testing slowdowns coincide with increasing or stable positive rates.

“The enhanced positivity rate is the thing that bothers people more than anything else,” said

Dr. William Schaffner, a professor of preventive medicine and infectious disease specialist at Vanderbilt University School of Medicine. “Because it suggests this virus is circulating still very briskly, especially in certain parts of the country – in fact, much of the country.”

WHO recommends 5% or fewer tests should be positive two consecutive weeks before a community loosens restrictions on businesses opening. If a positive test rate is above that benchmark, it's a sign an area is testing only the sickest patients and not adequately tracking the virus.

The average number of coronavirus tests reached 793,000 a day in the past two weeks of July. But testing dropped to fewer than 650,000 a day during the first 12 days of August, according to figures from the COVID Tracking Project.

More t han half of states nationwide have positive rates above 5%, and a dozen states are above 10%.

As testing has slowed, positive rates increased over the past week in 35 states as of Friday, according to Johns Hopkins University' s Corona virus Resource Center.

“If testing is going down and positivity is going up, that is what you would expect in an uncontrolled outbreak,” said Amesh Adalja, a senior scholar at Johns Hopkins Center for Health Security.

Although positive rates are still too high, Adalja sees positive signs, such as fewer hospitalizations and declining case counts.

Experts believe several factors are leading to a testing decline in parts of the nation.

A surge in testing demand in July showed more Americans sought tests than the nation's labs could process in a timely manner. Even when people got tested last month at a doctor's office, testing site or clinic, wait times ballooned – making it too late to trace contacts of an infected person.

Storms temporarily closed testing centers in states such as Florida, New York and New Jersey. And people might be more relaxed after an earlysummer surge in the South and West relented and case counts drop.

But experts say dropping case counts can be a deceiving sign when the share of positive tests holds steady or increases.