u.s. cases spike, new York declared epicenter


By: Kyle Freese, PhD, MPH

Daily summary 3/23/2020

Credit: WHO Situation dashboard

Global cases of COVID-19 raced past 300,000 this weekend and we should expect the trend to continue. It took us 67 days to reach the first 100,000 cases, 11 days to reach the second 200,000, and only 4 days to reach the third 100,000. This is what exponential growth looks like. I suggest watching the video I posted on Twitter on March 20 (@Epi_DrFreese) to help better understand this type of growth.

The U.S. is also experiencing its “first” surge in cases, though it is unclear how much of this initial spike is due to increased testing. In addition, New York has been declared an epicenter of the outbreak.

The worldwide epidemic curve below has been updated from my 18-March post. Before directly comparing the curves, note that the scale on this graph extends to 40,000 new cases per day- the previous figure went to 20,000.

Many public health and government officials have argued that the current challenge we are undertaking is akin to warfare. They are right. In the upper, right portion of this page is a proposed, adaptive response to COVID-19 from the former director of the Centers for Disease Control and Prevention (CDC), Dr. Tom Frieden. In summary, this plan stresses that plans must be agile, overlapping, and specific in their tasks. Every component that is part of the healthcare complex should consider how they fit into this type of response.


More historical lessons. Take this seriously.

As I point out in a recent op-Ed piece, we need to take seriously our individual responsibility for flattening the epidemic curve. Unfortunately, from what I have observed, many people struggle with the idea of preventive measures, particularly the important of social isolation. Again, I refer you to the video I posted on Twitter on March 20- in short, the presenter makes the point that everything is going to seem fine until it isn’t. The danger is that with exponential growth of a virus is that one day, you will know no one that is sick and the next, everyone will be sick. 

I understand why preventive isolation measures seem abstract and even unnecessary. In Arizona specifically, I bet most people do not know anyone who has been confirmed to have COVID-19. We have not yet experienced the exponential growth of the epidemic curve. The figure to the right shows the epidemic curves from the 1918 Spanish Influenza for Philadelphia and St. Louis (original in the Washington Post). Notice how the quickness of social distancing (i.e. isolation) in St. Louis resulted in a much flatter curve than the 5-fold spike observed in Philadelphia. The difference in time from first case definition to intervention between the cities? Two weeks. Two weeks goes fast. Especially in uncertain times like now, two weeks can seem like a blink. In Arizona, we are likely still in the mild growth phase of this pandemic, but make no mistake, without community-wide participation in isolation measures, we will likely reach a point that is being observed in other areas of the country. We are in a unique position to slow the spread.

     Overall, everyone has the personal ability and responsibility to do their part to protect the community at large. Keep up to date with new information from your local health department- wash your hand frequently, stay home, avoid crowds when running life-sustaining errands. I know it is difficult and frustrating, but as I have argued before, think of the individual sacrifices you make today as inputs that have an enormous return on investment.


Credit: A concept of operations for the war on coronavirus. Tom Frieden


Severe outcomes among patients with coronavirus disease 2019 (COVID-19) – U.S., February 12-Mar 16, 2020. MMWR Morb Mortal Wkly Rep. ePub: 18 March 2020. DOI: http://dx/

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For additional references, resources, or questions, please email Dr. Kyle Freese at