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In early February, the CDC picked 6 U.S. cities to find the coronavirus before it spread. They were “sentinel” cities. But it took a month or more to getting going, costing valuable time in detecting the virus. I’ve been looking into why (a thread…) 1/ https://www.npr.org/sections/health-shots/2020/04/24/842025982/why-the-warning-that-coronavirus-was-on-the-move-in-u-s-cities-came-so-late
The cities were supposed to use their existing flu surveillance systems to find coronavirus cases in mild patients. At the time, most didn’t meet CDC guidelines for testing. But by mid-March, about 5 weeks after planning began, only one city had test results back. 2/
Chicago started doing sentinel testing first in early March. What helped them was testing. Their state health lab could run the CDC’s test kits, while other states couldn’t. Still, after they found the virus was spreading, it took another week to issue the stay-at-home order. 3/
Los Angeles had a false start. County health officials were working with a hospital to do the sentinel testing, but the hospital’s board declined b/c it was worried about getting a stigma. Testing only went ahead when another hospital - @LACUSCMedCenter – offered to help. 4/
“This is a leading-edge indicator,” Dr. Brad Spellberg of @LACUSCMedCenter told me. "If you don't look at it, you're missing the canary in the coal mine. You're waiting for the coal mine to collapse on you." They found community spread - a stay-at-home order came 3 days later. 5/
New York City got a very late start. Its first results for sentinel surveillance testing came back on March 31, when there were already tens of thousands of cases. Not an early warning. 6/
Seattle clashed with CDC about surveillance testing. Washington state officials wanted to use the Seattle Flu Study, but as a research lab, it wasn’t certified for clinical work. The CDC said no at that time and it took another month to get the approvals in place. 7/
One place it seems to have helped: Santa Clara County in the Bay Area. It wasn’t part of CDC’s original list, but got surveillance testing going in mid-March. They found 11% were positive - to their surprise. The entire Bay Area was ordered to at stay at home 2 days later. 8/
Could earlier sentinel surveillance have made a difference and saved lives? The CDC told me it doesn’t think so and the delays had to do with the challenges of dealing with a new virus. But several epidemiologists I spoke to disagreed. 9/
"It does feel like we lost time," @JenniferNuzzo, an epidemiologist at @JohnsHopkinsSPH told me. "As we learned that this disease was spreading — and spreading efficiently — between humans, we should have stood up sentinel testing in the United States." 10/
Ending this thread with a big thank you to everyone who took the time to speak with me and everyone else @nprscience during this hectic time. We couldn't do it without you.
