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Social distancing in Virginia has slowed the spread of COVID-19. When restrictions start to ease, testing and tracing likely infections will be the only way to make sure cases don't spike and overwhelm hospitals.
How much testing is enough? Where are we now? A thread >
How much testing is enough? Where are we now? A thread >
We looked at Virginia's progress on three key targets:
-Tests 10K per day, @GovernorVA's goal
-Test 2% of the state population every 30 days, per Harvard/federal gov
-Show a 10% rate of positive cases among all test everyday, per WHO https://www.richmond.com/special-report/coronavirus/virginia-misses-key-marks-on-virus-testing-as-leaders-eye-reopening/article_021e12c6-6d20-5030-9068-4caaeda495f7.html
-Tests 10K per day, @GovernorVA's goal
-Test 2% of the state population every 30 days, per Harvard/federal gov
-Show a 10% rate of positive cases among all test everyday, per WHO https://www.richmond.com/special-report/coronavirus/virginia-misses-key-marks-on-virus-testing-as-leaders-eye-reopening/article_021e12c6-6d20-5030-9068-4caaeda495f7.html
Virginia isn't meeting any of those targets. Before diving into that, know this:
Virginia's already low testing numbers are likely inflated by antibody test results, the state confirmed Friday. These tests have not been vetted by federal regulators/not trusted by experts.
Virginia's already low testing numbers are likely inflated by antibody test results, the state confirmed Friday. These tests have not been vetted by federal regulators/not trusted by experts.
Virginia's own health experts have said antibody tests are not yet reliable. The state doesn't not know how of those tests are among those in its total count. A VDH spokeswoman said the agency was working to “disaggregate them from the other test results.”
It's not clear how Virginia arrived at its goal of 10K tests per day, but Gov. Northam said it is the key to reopening the state.
The state averaged around 5,200 tests a day over the last week. On Wednesday, VA reported a peak of more than 9,000 tests and just 2,500 Monday.
The state averaged around 5,200 tests a day over the last week. On Wednesday, VA reported a peak of more than 9,000 tests and just 2,500 Monday.
Researchers at Harvard argue states should test 2% of their populations every 30 days — a more conservative goal than Northam's.
Virginia would need to average 5,700 tests/day, not far from where we are now. Still, over the last 30 days, VA tested about 1.4% of its population.
Virginia would need to average 5,700 tests/day, not far from where we are now. Still, over the last 30 days, VA tested about 1.4% of its population.
“Testing is everything,” said Erin Sorrell, a virologist and public health expert at Georgetown University whom I reached to explain the 2% figure. “If you’re able to test 2% in that time frame, you’ll have a better indication of spread and where outbreaks are happening."
Whether the state is casting a wide-enough net — testing different types of populations / from all regions / with varying risks of exposure — may be more important than the sheer number of tests.
By that measure, Virginia's net is too small.
Bear with me on this one.
By that measure, Virginia's net is too small.
Bear with me on this one.
Public health experts, citing research from @WHO, argue that testing should so high that the sick account for a small share of everyone tested, ~10%. That'll mean you're testing a large enough sample to not risk missing cases.
In Virginia, the positive rate is at ~17%.
In Virginia, the positive rate is at ~17%.
With limited testing, the first people in line are ones who are really sick. Next are those with multiple symptoms or at high risk. Next are people with mild-symptoms or known exposure. Next are the asymptomatic.
Your net is wide enough when the sick make up a small share.
Your net is wide enough when the sick make up a small share.
“The fear that I have is that with a rate of positivity so high, they are missing many cases and their view of how much illness is in the state is not accurate because they haven’t tested as much as they need to,” said Jennifer Nuzzo, an epidemiologist with Johns Hopkins.
Virginia health officials/experts are looking at both the 2% goal from Harvard and the 10% WHO guideline.
Em Stephens, a state epidemiologist working on the team analyzing COVID-19 trends, said: “That is the goal.” https://www.richmond.com/special-report/coronavirus/virginia-misses-key-marks-on-virus-testing-as-leaders-eye-reopening/article_021e12c6-6d20-5030-9068-4caaeda495f7.html
Em Stephens, a state epidemiologist working on the team analyzing COVID-19 trends, said: “That is the goal.” https://www.richmond.com/special-report/coronavirus/virginia-misses-key-marks-on-virus-testing-as-leaders-eye-reopening/article_021e12c6-6d20-5030-9068-4caaeda495f7.html
Stephens: “We are not doing enough testing right now. Hopefully it’s clear that we are ramping up. ... Once we expand testing capacity, we can start looking in places where we are less likely to find it." https://www.richmond.com/special-report/coronavirus/virginia-misses-key-marks-on-virus-testing-as-leaders-eye-reopening/article_021e12c6-6d20-5030-9068-4caaeda495f7.html
To contain positive cases, Virginia is also planning to build up its contact tracing workforce — the people who track the recent contacts of anyone that tests positive.
Right now, VA employs just 325 tracers. The guidelines from one group of health directors suggest 2,550.
Right now, VA employs just 325 tracers. The guidelines from one group of health directors suggest 2,550.
There are bright spots: Virginia’s hospitals are not reporting supply shortages, demand for hospital beds is below capacity and the number of people in the ICU COVID-19 has remained flat.
But, 4 days away from reopening, the state is missing key marks. https://www.richmond.com/special-report/coronavirus/virginia-misses-key-marks-on-virus-testing-as-leaders-eye-reopening/article_021e12c6-6d20-5030-9068-4caaeda495f7.html
But, 4 days away from reopening, the state is missing key marks. https://www.richmond.com/special-report/coronavirus/virginia-misses-key-marks-on-virus-testing-as-leaders-eye-reopening/article_021e12c6-6d20-5030-9068-4caaeda495f7.html
