Thread by @DearPandemic

1/ Q: How are #COVID19 cases increasing but deaths are decreasing in the U.S.?

A: Timing, timing, timing. And some other factors too.⏰⁠
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vox.com/2020/7/6/21314…

2/ We have to remember that it takes individuals who develop symptoms, an average of 5 days from the date they are infected to when they start to feel sick, but the range of time before individuals develop symptoms is more like 2-14 days.

3/ Once symptoms start, it may take individuals a few more days/weeks to develop symptoms severe enough to require hospitalization. People may then be hospitalized for days to weeks before unfortunately dying from COVID-19.

4/ So, the spikes in cases we are seeing now may still take a few more weeks to translate to a rise in deaths and if and when we do start to see spikes in deaths, this likely corresponds to infections that were acquired ~4-6 weeks ago.⁠
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5/ In some states the mean age of new cases has also dropped significantly with people in their 20s & 30s now making up a substantial proportion of total cases to date.

6/ While younger individuals are not exempt from the possibility of dying from COVID-19, it may be that we won’t see a spike in deaths until infection spreads from younger individuals to others who are more vulnerable to complications in their communities.

7/ In other words, the timeline between initial spike in cases to a related spike in deaths may be extended if the initial surge in cases is primarily among younger individuals.⁠
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8/ Another consideration is that as testing & contact tracing capacity grows, we are able to test earlier in the course of infection. This produces something called “lead time bias” which could also be playing a role in extending the time it is taking for deaths to increase.

9/ As time goes on, better treatments are becoming available which can potentially improve survival. We can also proactively #StaySMART in our day to day interactions and work to protect those who are vulnerable to complications in our family and communities.⁠