The U.S. has performed 8 million tests to date — the most out of any country by far — but researchers say that’s not the only number to consider when evaluating plans to reopen states and stopping the spread of the virus.
Researchers at Johns Hopkins University are going beyond the numbers – tracking coronavirus trends in real time.
“The case numbers alone don't tell you everything you need to know,” said Dr. Jennifer Nuzzo, senior scholar at the Johns Hopkins Center for Health Security. “They may only represent the tip of the iceberg.”
They launched the Testing Insights Initiative – an online tool analyzing cases at the national level and state by state.
Of all the people screened for COVID-19, most test positive for the virus.
“The states are probably only testing the sickest of the sick and likely missing the whole kind of bottom of the iceberg of infected individuals out there who may not be sick enough to show up at a health facility but are very much capable of spreading their infection,” Nuzzo said.
Positivity rates should be under 12 percent, she said.
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Compare that to South Korea, which made headlines for its aggressive testing. Its positivity rate is less than 2 percent.
Nuzzo said she’s concerned because some states that are reopening right now haven’t done enough testing to capture a realistic snapshot of infections.
“States may have kind of a distorted view of how much illness is in their communities, and when they reopen and people go back to mixing together and exposing each other, they may very well see a rapidly accelerating case numbers,” she said.
It can take weeks to identify new cases and trends.
“It isn’t until the virus spreads to the more vulnerable people who tend to get very sick at health facilities and then suddenly you have all of these people showing up at health facilities seemingly out of nowhere,” Nuzzo said.
Test numbers may also be misleading because they don’t always account for a single patient.
“Some patients get more than one test, but that's not really made clear when they report the numbers of tests performed,” Nuzzo said.
Countries like Taiwan and New Zealand have not done a lot of testing but slowed the spread of the coronavirus with strict contact tracing methods.
Nuzzo said that will be key here as the U.S. slowly emerges from life in lockdown.
“The purpose of these measures were to basically hit pause,” Nuzzo said. “The disease spread. It is not a cure. It doesn't stop the virus from circulating. It didn't make the virus go away. As soon as we hit the pause button again and press play, the virus is still out there.”
To prevent a second wave of cases, states need a focus on how they’ll identify and isolate positive cases as well as tracking and quarantining their contacts.
Nuzzo said our region has not done enough testing but Maryland gets high marks for its aggressive approach to testing at nursing homes, which account for almost half of the state’s deaths.