On: Comparing COVID-19 to past pandemics, preparing for the future, and reasons for optimism

Episode: 106

Date: 13 April 2020

Senior Scholar at the Johns Hopkins University Center for Health Security. focused on emerging infectious disease, pandemic preparedness, and biosecurity.

Key Subjects:

• Spread.
  • COVID-19 may have spread outside of China prior to December 2019, but if so, sporadically.
• Fatality.
  • Novel flu (1958): about 100,000 people.
  • Worst regular flu season (2017/18): about 80,000 people.
  • H1N1 (2009): spread to 61 million, but very low mortality.
  • Avian influenza: 65% mortality.
  • COVID-19:
    • Previously over-estimated (denominator too low).
      • Severity bias: only people with severe symptoms are tested.
      • Also, previous models over-estimated hospitalization rate.
        • Not 15-20%, probably closer to 5%.
    • CFR likely below 1%.
      • Perhaps in the 0.3-0.7% range.
    • On average.
      • Subject to age and underlying conditions.
    • For US, final number probably close to current 60,000 people estimate.
• Versions.
  • Common versions:
    • Ubiquitous: spread easily, commonly infect humans globally.
    • Mild in symptoms (cause about 25% of our colds).
    • Recur seasonally.
    • Four versions: 229E (alpha), NL63 (alpha), OC43 (beta) and HKU1 (beta).
  • Other versions: evolves in animals, transmitted to humans.
    • Mostly animal to human transmission.
    • Outbreaks mostly occur in hospitals, difficult to sustain in human population.
    • MERS-CoV (beta), SARS-CoV (beta).
  • SARS-CoV-2 may become fifth common version.
    • Spreads very easily.
    • Until there is a vaccine.
• Slow response.
  • Testing criteria too strict.
  • Scarcity of testing materials.
  • Bureaucratic snafus (see als The Grumpy Economist on April 13, 2020).
  • Lack of “diagnostic curiosity”.
• Back to normal.
  • Lessening restrictions on schools, social distancing, businesses, hospitals.
  • Still avoid mass gatherings.
• Sweden.
  • Herd immunity approach: comes with increase in cases.
  • Success depends on ability to sequester high risk groups.
  • Who is getting sick will determine ability to keep peak within health care capacity.
• Masks
  • Not very helpful to the public.
  • Those with symptoms: wear mask to prevent spreading.
  • Those without symptoms: open question how much it helps to prevent spreading.
• Selected signs of plateauing.
  • Downsizing surge capacity / field hospitals.
  • Returning ventilators to national stockpile.