I've edited the pages I've selected, taking out references and some of the calculations. Anyone who thinks I misrepresent things is free to check the original. On the last page re medications, I've simply used the heading. The pages I've selected--the full powerpoint presentation has a total of 37--are the ones that I believe will be most informative for most readers, but if you go to the original you'll find additional information on how Covid-19 kills, etc.
As you'll see, as I've been arguing, Lin believes the US is still early in the process--which gives us hope. OTOH, pandemics like this can develop and get out of control rapidly. You'll see below that Lin crunches the numbers and figures that this may not peak in the US until May - June, but that we need to act by, well, right now. The period March 16 to April 16 will be critical in Lin's estimation.
That's the bad news, but the good news is that that's what will happen if we do nothing. We're already doing something, and Lin's estimates give us a metric by which to measure--are we doing enough?
Is it possible that Lin is off in his estimates? Yes. Why, then, is this important? Because this is probably very close to the type of presentations President Trump and others are receiving and on which they are basing their policy decisions. If public official's appear to be freaking out--this is why. Trump will have in mind the time frame that Lin outlines in formulating his policies. If Lin and others are right, the worst is well ahead of us, but we can try to mitigate it. Read this, and you'll have some idea why public officials are doing what they're doing from a medical standpoint. You already know why they're doing what they're doing in the stock market.
We are still early in the process
What should we do when 1 in 1000 in the Bay Area just got the virus?
• About 50% of patients will be asymptomatic, based on experience with the Diamond Princess, an estimate from Wuhan data, and an estimate from passengers on evacuation flights.
• Average incubation period is ~7 days. Transmission may begin 2 days before symptoms, so on average at 5 days after infection.
• Thus the 1 in 1000 who just got the virus this week will start spreading virus and then develop symptoms over the next week (obviously not synchronized but continuously over time).
• We can protect ourselves against any undetected spreaders by keeping our hands and common surfaces clean, and maintaining distance when we talk (and use of face masks if you’d like).
• Risk is 1/1000 from direct personal contact; higher from touching fomites [surfaces capable of carrying infectious organisms] in proportion to the number of people touching them between cleanings.
• Take action to reduce a currently low risk of acquiring/transmitting the virus to as low as possible.
3/20/20 Michael Lin, PhD-MD 13
How bad could this be?
• If we did nothing and doubling rate remains 1 week, then in worst case, deaths and infections will grow exponentially until virus runs out of people to infect (using CA-only numbers now).
• For US numbers, multiply by 8: ~2M (million) cumulative deaths.
• This is not meant to be numerically accurate, it’s just for illustration, but it fits well the worst-case scenario by an authority in disease modeling.
• Compare to Spanish flu of 1917-1918: Cumulative infection rate 27%, IFR 2%. Spanish flu might have higher IFR than COVID-19, but medical care was much worse then (no ventilators, no drugs). In reality COVID-19 is likely the more severe disease. In any case, Spanish flu was devastating.
3/20/20 Michael Lin, PhD-MD 14
• Estimated 5% of total infected (not diagnosed cases) require hospitalization and 2.5% require ICU. Average hospital stay is 3 weeks, and starts 2 weeks after infection (1 week after diagnosis).
• Wuhan numbers are 15%/5% of cases, but that is with smoking (60% of males) and pollution (everyone), also infection rate underdetected by 50%.
• Biggest infection surge occurs in the weeks of 5/15, 5/22, and 5/29, when 10%, 20%, and 20% of population = 32M, 64M, and 64M get infected. This will result in 1.6M, 3.2M, and 3.2M needing hospitalization starting 6/7, 6/13, and 6/20. As patients need to stay ~3 weeks, 8M will overlap on the week starting 6/20.
[My rough table]:
Big surge: 5/15, 5/22, 5/29
% infected: 10%, 20%, 20%
# infected: 32M, 64M, 64M
Need Hospital: 1.6M, 3.2M, 3.2M
Date to Hospital: 6/7, 6/13, 6/20
– <1m beds="" hospital="" in="" p="" us.="">– So we must slow down doubling time from 1 week to ~8 weeks, so hospitalizations peak at at <1m .="" b=""> 1m>1m>
<1m beds="" hospital="" in="" p="" us.="">
1m> <1m beds="" hospital="" in="" p="" us.=""><1m .="" p="">3/20/20 Michael Lin, PhD-MD 15
We need to ‘flatten the curve’ now
The next month is critical: March 16 to April 16. We must do whatever we can to reduce R0 or increase doubling time. It will take several weeks to know if it’s working.
If we are still doubling each week on April 16, we have only another month to get a second chance.
If that doesn’t work by May 16, there will be no third chance. We would have to immediately clamp down to avoid hospital overflow. This would require Wuhan-like measures such as central quarantine for sick and enforced home-isolation for everyone else.
3/20/20 Michael Lin, PhD-MD 16
What can flatten the curve?
• Weather: Maybe 10 oF increases the doubling time 2x
• Goal is to reduce the reproductive number R0 (how many people infected by each patient).
– Current R0 rate ~ 2 (one person infects 2 others. If they do this in 7 days, it explains doubling time of 1 week).
– Drop R0 to 1.5: Doubling time would increase ~2-fold.
– Drop R0 to 1.25: Doubling time would increase ~4-fold.
– Drop R0 to 1.125: Doubling time would increase ~8-fold.
– Drop R0 to 1.0: Doubling time would become infinite (constant rate of new cases).
• Social distancing, wide testing and tracing, and strict hygiene (face masks, hand sanitizer): This is the approach in SK, Taiwan, Singapore, HK. This seems to have dropped R0 to 1.0 (constant rate of new cases).
• Complete household isolation, immediate quarantining of symptomatic, strict hygiene: This was the approach in Wuhan. R0 dropped from 3.9 to 0.32.
• Is presymptomatic or asymptomatic transmission a factor? Yes, but how much is unclear.
– In Wuhan, R0 fell from 1.3 when symptomatic patients stayed at home to 0.32 when they were centrally quarantined. This suggests only 24% of transmission events occurred before symptoms. But another study estimates 44% of transmission is in presymptomatic period.
– How about asymptomatics? Undiagnosed carriers estimated to be ~55% as infectious as diagnosed cases. As undiagnosed carriers are more likely asymptomatic than diagnosed cases, this suggests asymptomatics are not as infectious as symptomatics.
3/20/20 Michael Lin, PhD-MD 17
It’s not easy, but social distancing, fast testing, and immediate quarantining can be enough!
3/20/20 Michael Lin, PhD-MD 18
Thanks to earlier research, we already have drugs with activity against the virus
3/20/20 Michael Lin, PhD-MD 19