The Last Thing We Need Is Fewer Tests: This Week in COVID-19 Data, Aug 6

Something new happened in COVID-19 data this week: For the first time since early March, the number of people tested in the United States went down. This week’s tests were 9.1 percent lower than last week’s national peak of 5.7 million tests. In absolute terms, we lost half a million tests. New cases of COVID-19 were also down this week by 10.4 percent. That percentage decline looks uncomfortably close to the drop in testing numbers, but probably can’t be entirely explained by the reduction in testing. Deaths, meanwhile, rose for the fifth straight week, trailing the huge surges in new cases in June and July. This week in the United States, 7,591 people died of COVID-19.

To understand the movement of the pandemic in a way that is slightly less dependent on testing capacity, we look at current COVID-19 hospitalizations, which have also dropped 7.5 percent from last week’s all-time high of nearly 59,000 people. Note: Hospitalization numbers do rely on testing, to some degree, but even in states that report only patients with lab-test-confirmed cases of COVID-19, tests performed on patients sick enough to be admitted to hospitals are likely to be given highest priority in testing labs.

As we’ve written about here, COVID-19 hospitalization numbers have been incomplete in recent weeks as hospitals staggered under new federal reporting requirements. It may be that many hospitals across the country are still reporting incomplete data to their states—or not reporting at all—so it’s possible that the week-over-week declines do not precisely reflect reality. Still, the overall trend in the data we compile from state reports shows current hospitalization numbers that appear to closely mirror those states’ new-case curves. We suspect that even if the absolute numbers are an undercount, hospitalization data reporting has stabilized enough that this metric can once again act as a rough reality check in states where testing declines may be masking new case growth. 

But where did the tests go?

The national testing figures for the United States are a summary of public data points reported by 50 states, five territories, and the District of Columbia. The act of cobbling together these disparate numbers into a national figure obscures the fact that each of the dozens of outbreaks in the United States moves differently, and each state’s circumstances are unique. The decline in testing we saw this week is due in part to highly specific problems within the nation’s three biggest hotspots: 

• Hurricane Isaias made landfall this week in Florida, and the state saw sharp testing declines after closing testing sites as a safety measure. (As the storm swept up the Eastern Seaboard, communities in many other states experienced extensive power outages that may have delayed testing and reporting.)

• California, the most populous state in the country and home to several major outbreaks, discovered that its computer systems were failing to communicate an unknown percentage of test results submitted by labs—for as long as three weeks. 

• In Texas, testing has declined by slightly more than 20 percent with no clear single cause in the past ten days—a period when the state’s hospitalization and death data has also been unusually unstable.

Nevertheless, underneath the data wobbles produced by state-specific events, familiar testing issues remain in nearly all states: ongoing supply-chain problems, insufficient capacity at testing sites to meet demand, and backlogged testing labs. These are the same kinds of problems the country has been facing since the pandemic began. Our testing capacity has scaled up enormously since March—but so have the COVID-19 outbreaks that have surged across the South and West all summer, requiring the country to perform ever-greater numbers of tests just to keep pace with the virus. 

Weeks ago, major US testing companies and public health experts began warning that our national testing capacity was dangerously strained. This week, testing in the United States seems to have hit a wall.

Beyond the biggest outbreaks

Worsening problems with testing have sprung up across the United States. A look at local reporting helps contextualize some of the declines we’ve seen.

• In Minnesota, where the seven-day average for testing is down 30.5 percent in the past ten days, the state has fallen well short of the stated 20,000 daily test goal. The growth of our Southern outbreak has impacted reagent supplies across the country. As Dr. Mark Sannes of Minnesota’s HealthPartners lab notes, “There really is a finite supply of that nationwide. ... We are not able to get everything we're asking for.”

• In Alabama, tests have sloped gradually downward since mid-July and the seven-day average has fallen 13.5 percent in the past ten days, even as the state’s hospitalization numbers remain near their peak. It takes an average of seven days for Alabama residents to get back test results—far too long to allow for useful contact tracing measures and preventing secondary infections.

• In Mississippi, the seven-day average for tests has fallen by more than 25 percent since July 22, and the state’s percent-positive rate leads the country. Meanwhile, 51 of the state’s 144 school districts plan on reopening with in-person learning this week. 

• In Nevada, where the seven-day average for testing has fallen more than 15 percent in the past ten days, casinos remain open. The state recommended on July 23 that members of the public without known exposure to a confirmed COVID-19 case stay away from drive-through testing sites in order to preserve limited testing capacity. 

Against this backdrop of falling tests, deaths continued to march upwards for the fifth consecutive week. Only five days into the month, more people have been lost to COVID-19 already in August than were reported to have died in all of March.

What’s next

As testing declines in many US regions, K-12 schools, colleges, and universities have begun to reopen for in-person classes in many US states, we have already begun to see on-campus and residential outbreaks that mirror those we’ve seen from summer camps. In Hong Kong and Israel, where the pandemic was under greater control than it remains in the United States, school reopenings were followed by spiking outbreaks. Evidence also suggests that US school closures this spring were associated with a sharp reduction in new COVID-19 cases. In some US communities at least, school authorities plan to stay the course despite finding positive cases among students. 

If widespread in-person learning continues in areas with high levels of community spread, we expect to see cases begin rising more sharply through the fall and into early winter. As with state reopenings in late spring, we expect that there will be a delay between increased exposures related to in-person classes and rising case counts. Inconsistent school-start dates, mitigation policies, and existing outbreak severities mean that we should expect that once again, this lag will be unpredictable—but more exposures will eventually show up in the data as rising cases, hospitalizations, and deaths.