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One signal Mr. Kucharski looks for is when the first case in an area is a death: “That suggests you had a lot of community transmission already,” he said.
“Suppose the fatality rate for cases is about 1 percent, which is plausible,” he continued. “If you’ve got a death, then that person probably became ill about three weeks ago. That means you probably had about 100 cases three weeks ago, in reality.”
“In that subsequent three weeks, that number could well have doubled, then doubled, then doubled again,” he added. “So you’re currently looking at 500 cases, maybe 1,000 cases.”
When considering the fatality rate, Mr. Kucharski suggested people pay attention to the variable risk level for different age groups, particularly people in their 70s and 80s.
“Over all we’re seeing maybe 1 percent of symptomatic cases are fatal across all ages,” he said. “What’s also important is that 1 percent isn’t evenly distributed. In younger groups, we’re talking perhaps 0.1 percent, which means that when you get into the older groups, you’re potentially talking about 5 percent, 10 percent of cases being fatal.”
That’s it for this briefing. See you next time.
To Mark Josephson and Eleanor Stanford for the break from the news. You can reach the team at email@example.com.
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