Epidemics begin in one of three model independent ways.

  • Exponential (Incidence accelerates rapidly)
    • 1918 Influenza (San Francisco, 1918)
    • Plague (Bombay, 1905)
    • Smallpox (Khuina, Iran, 1977)
  • Power (Incidence increases day by day)
    • Measles (London, 1948)
    • HIV/AIDS (New York City, 1982 – 2002)
  • Linear (Incidence remains constant)
    • Heart Disease
    • Cancer  

 COVID-19 in New York City illustrates one such pattern. Tab through and see for yourself.

 

 Epidemics begin in one of three model independent ways.

  • Exponential (Incidence accelerates rapidly)
    • 1918 Influenza (San Francisco, 1918)
    • Plague (Bombay, 1905)
    • Smallpox (Khuina, Iran, 1977)
  • Power (Incidence increases day by day)
    • Measles (London, 1948)
    • HIV/AIDS (New York City, 1982 – 2002)
  • Linear (Incidence remains constant)
    • Heart Disease
    • Cancer  

 COVID-19 in New York City illustrates one such pattern. Tab through and see for yourself.

First 5 Days

 

The first 5 days were unremarkable to many - only a few cases.

Perhaps 4 more cases each day than the day before.

First 5 Days - ??

 

The epidemiologists at the Public Health Department saw a very different progression of cases - an exponential growth of cases.

Day 6

 

Day six brought more cases than expected from a simple linear growth pattern.

Perhaps a growth according to a power function (a quadratic equation)?

Perhaps an exponential growth?

Day 7

 

Yes - an exponential !

New cases on day seven were definitely on the exponential curve!!

First 2 Weeks

 

! ! Plague ! !

Remarkably - the first 5 days predicted the course of the COVID-19 epidemic over the next two weeks.

The Mayor was convinced, and within days the Governor was too. The city closed down!

The Next Month

The next month did slow the epidemic to a linear growth pattern - averaging 4,600 new cases a day!

 

Finally - A Pause

Finally, a pause after two months.