14 March 2020 Blog Post: Where Are We Going Based On Where Have We Been?
This seems to be the most common question I have been getting, particularly of late. Where is this all going? We have all been impacted now by school closures, “social distancing”, travel disruption, working from home and increasing isolation from friends and family. So what can we expect in the upcoming days and weeks?
At this writing there are 155,423 total confirmed worldwide cases of which 2,572 are in the United States. I think we all agree that the US numbers are a massive underestimate of the true burden of infection but what does that mean practically? We are also clearly on the upswing, both in terms of case identification and as #COVID-19 spreads (see Figure 1 below). As Dr. Anthony Fauci stated, “I can say we will see more cases, and things will get worse than they are right now.”
So how many more cases and how much worse? For those of you who are fans of Chris Cuomo – let’s get after it!
Agreeing that 2,572 identified cases is an underestimate, where do we suppose that the actual number of current infections in the US stand? Trevor Bedford, who is a scientist Fred Hutch and is well worth following on Twitter has studied the King County Washington COVID-19 data in incredible detail. His analysis based on that flare suggests that we are currently operating at a 1:10 to 1:20 case to infection reporting rate. That would indacted that we have anywhere between 25,000 and 50,000 cases already in the US.
Thus far, a 5-6 day doubling time has been an accurate model for growth as the “appearance of outbreaks across the US are not due to a sudden influx of cases but instead transmission chains that have been percolating for 4-8 weeks now.” We are just now starting to see the exponential growth “pick up steam.” (Quotes are Dr. Bedford’s words – giving credit where credit is due).
This is an important time in the epidemic curve for, if you look at Figure 2 from the coronavirus outbreak in China, you can see that cases rose rapidly just after 40,000 infections. The line is nearly vertical at one point before flattening.
Laurie Garrett (who is a scientific journalist and known for her reporting on the Ebola virus outbreak in Zaire and also worth following on Twitter), estimated 30,000 cases in 10 days. This, however, I believe is a significant underestimate. Given what China reported between mid February and early March, I would estimate that the US should prepare for 80,000-100,000 cases. Note too that the number of cases in Figure 2 flattens dramatically towards the end of February – this from aggressive containment measures by Chinese public health officials.
Doubling time varies dramatically by country. The US, Germany, France and Spain have a 3 day doubling time (now some of this in the US may be due to case detection as testing has not been widely available), In Italy it is 4 days. Iran 6 days. South Korea – 12 days. Currently in China – 32 days.
“Hope is not a strategy,” says Mike Ryan, who is an epidemiologist and the World Health Organization’s head of emergencies. “We are still very much in the up cycle of this epidemic.”
At Santa Monica Primary Care we continue to be available for any questions and concerns you may have. We can be reached 24/7 by phone at (310) 828-4411. While the major bottleneck we have faced thus far is the availability of any testing, we hope that changes soon allowing us to identify both cases and those who remain unaffected.
𝗦𝗶𝗴𝗻 𝗨𝗽 𝗳𝗼𝗿 𝗢𝘂𝗿 𝗡𝗲𝘄𝘀𝗹𝗲𝘁𝘁𝗲𝗿
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