Friday, March 13, 2020

What is a pandemic vs. an epidemic?

The World Health Organization (WHO) on March 11, finally issued the official decree -- COVID-19 is now a "pandemic".

The WHO has criteria for phases of pandemic influenza and they have applied that criteria to Bird Flu and even SARS. There are three criteria that must be met, which you can see from the WHO graphic. First, that the disease is contagious to humans or animals; second, there must be a sustained human to human transmission; and third, it must have "widespread human infection". Even after 34 countries were reporting cases of human to human transmission of COVID-19, WHO had not yet determined this met the "widespread human infection" criteria and many were wondering what it took to meet that criteria, if not 34 countries?

It took 114 countries. 

The WHO Director-General in his remarks, said that "In the past two weeks, the number of cases of COVID-19 outside China has increased 13-fold, and the number of affected countries has tripled."  Further, " we are deeply concerned both by the alarming levels of spread and severity, and by the alarming levels of inaction."

This graphic shows the decision-framework WHO uses to assess where we are in the phases before and after a pandemic. The announcement on March 11 is the Phase 5-6/ Pandemic phase. Look for WHO to next consider "post peak" status, hopefully in the near future. Since China and the Republic of Korea have 90% of the cases and have now shown declines in new cases, that's a good sign for the rest of the world. The move toward "post peak" for these two major nation contributors to the number infected indicates other countries should follow that drop in reported cases in the coming weeks depending on the controls and government interventions. 

Let's hope for the post peak announcement this spring.

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