From Mitigation to Suppression: In collaboration with NPR, HGHI is publishing new state testing targets for July. This new data shows only 18 states meet minimum targets for mitigation, and only three reach suppression level testing.
In collaboration with Microsoft AI for Health, the Harvard Global Health Institute is also building out a dashboard (see top of the page) that displays testing targets for the U.S. and many other nations around the world, and allows us to track progress towards them in real time.
For a few weeks now, we have been thinking about updating our testing targets. Much has changed in the nation since our last update in mid-May. Outbreaks have retreated in some states and grown in others. The U.S. has quickly reached the highest case count and highest death toll of any nation in the world.
We have also learned a lot about this coronavirus, and about how we can best use testing targets not as an ultimate goal but as a tool on the path to zero cases. And we have begun to work closely with the Safra Center for Ethics at Harvard and other researchers, public health and policy experts across the U.S. to align on key aspects of what we think is needed to get the nation back on track.
Five months into this pandemic, what we need more than ever is still a robust testing, tracing and supported isolation infrastructure, combined with various measures of social distancing, mask wearing and hand washing. We have made some progress, but not nearly enough. Unsurprisingly, new daily cases are reaching record highs, and getting ahead of this virus seems all but impossible.
Except, as many public health experts know, it is not impossible. We have tools at our disposal, and other nations are using them with great success. So, why don’t we?
This is why in this update, we include both mitigation and suppression level testing targets. The pandemic is just getting started -- it is time to invest in building the capacity and infrastructure to test millions of Americans every day, symptoms or not. It will save many lives and billions of dollars.
Currently, a lot of states are essentially aiming for mitigation level testing: The focus is on reducing the spread of the virus through broad testing of symptomatic people, tracing and testing a recommended 10 contacts per new case and isolating positive contacts, and social distancing, mask wearing or stay-at-home orders as necessary.
There is a challenge with this approach: As states open up, mitigation level testing is often not sufficient to prevent new outbreaks.
With strict social distancing orders in place, cases go down, but then spike back up again as a state loosens restrictions. It's a rollercoaster of recurring outbreaks that creates great uncertainty, for example around reopening businesses, schools, and other vital parts of the economy.
Currently, in the U.S., these states meet or exceed our mitigation level testing targets: Connecticut, Delaware, Idaho, Illinois, Indiana, Maine, Massachusetts, Montana, New Hampshire, New Jersey, New York, Oklahoma, Washington D.C., West Virginia, and Wyoming, with Michigan and North Dakota being just a few tests away from meeting it.
And states that currently have the largest outbreaks -- Arizona, Florida, Mississippi, South Carolina-- are falling far short of meeting mitigation level targets.
This is because they opened up before suppressing the virus, and don't have a robust testing infrastructure in place so they can’t keep up.
Suppression level testing allows a state or community to quickly find and isolate new cases before they lead to a wider outbreak, with an aim of keeping new case levels at or near zero.
This requires large, proactive testing -- including regular testing of asymptomatic people in high-risk environments such as nursing homes, colleges, and parts of the service industry -- paired with rapid contact tracing and supported isolation (TTSI), as well as other measures. Several states are working hard to build and maintain this type of response, including Massachusetts, New York and Connecticut.
New York, an epicenter of the pandemic just two months ago, has seen remarkable progress toward suppression with consistently falling infection rates. While the state hasn’t reached full suppression levels yet, it is testing 60,000 people daily, more than twice its mitigation target (that’s one-tenth of all tests nation wide) and is showcasing what the path to zero looks like.
Suppression level TTSI programs reduce uncertainty and allow life to return to something closer to normal -- but still include mask-wearing, social distancing, handwashing and other measures. It is easier to do when case counts are relatively low or on the decline.
Only three states, Vermont, Hawaii, and Alaska are currently meeting suppression level targets, with West Virginia, Montana, and New Jersey very close behind.
So while testing has doubled in the nation since our last estimates in May (from around 250,000 to more than 550,000 daily tests) we are nowhere near where we need to be. We need to build capacity to test millions of people every day – around 4 million based on our latest modeling. That is an ambitious goal, but it is how we can suppress the virus, revive our economy and return to a new normal.
Population: Population of the state in millions of people. Taken from American Community Survey data
July 6 Cases: Number of estimated new COVID-19 infections on July 6. Obtained from Youyang Gu COVID-19 Forecasts on June 29, 2020.
July 6 Symptomatic Cases: Number of new symptomatic COVID-19 Cases on July 6. Calculated as 0.80 * July 6 New Infections. This is based on CDC estimates that approximately 20-50% of COVID-19 cases are asymptomatic.
July 6 Contacts: Number of contacts to test based on new infections on July 6. Calculated as 10 * July 6 Symptomatic Cases. We assume that during mitigation, a jurisdiction will initially test all symptomatic people thus we will only identify symptomatic cases and thus only will trace contacts for symptomatic cases. Ability to trace contacts varies widely but given some measure of continued social distancing it has been estimated at an average of 10 contacts per infected individual is the minimum goal to reach.
Other Influenza Cases on July 6: How many non-COVID symptomatic cases we expect to see on July 6, based on CDC Historical Influenza Surveillance data.
Total Tests (Contact Tracing and Isolation): Estimated number of tests needed given a strategy of testing all symptomatic individuals and contacts of those with positive tests. Calculated as the sum of July 6 Symptomatic Cases, July 6 Contacts, and Other Influenza Cases on July 6.
July 6 Cases: Number of estimated new COVID-19 Cases on July 6. Obtained from Youyang Gu COVID-19 Forecasts on June 29, 2020.
Total Tests (3% Positive Rate): Estimated number of tests needed given a strategy of reducing the positive rate of testing below 3%. This is calculated as 33 times the number of July 6 infections. A network of research, policy, and public health organizations convened by Harvard and MIT called the TTSI Collaborative has agreed on a 3% test positive rate or below as a key indicator of progress towards suppression level testing. This targets broad and accessible testing for symptomatic and asymptomatic people. Out of the positive tests that do not come from hotspot testing, at least 80% should come from contact tracing.
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