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.
- Previously over-estimated (denominator too low).
- 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.
- Common versions:
- 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.