Below is a letter that was forwarded to me written by David Kriebel, PHD... Epidemiologist from the school of public health at UMass Lowell.
I then forwarded it to a client who shared it with his golfing buddy who happens to be a retired CEO of a major "big pharma" corporation. His response will follow after this letter...
Thinking of you all, and hoping you are well. I’ve been following the research on the epidemiology of corona pretty closely as it emerges day by day, and I thought you might appreciate a brief perspective. I very much agree that the best things that we can do right now to slow the epidemic are the personal hygiene and social distancing that everyone is talking about. In the U.S., we may be a little behind already in these responses, but we must try. The time to enact strong measures is before there are cases popping up all around us. In other words, limit social contacts as much as you can, right now.
But I want to add some modestly encouraging news as well.
I just read a paper out yesterday by epidemiologists in Wuhan and at Harvard analyzing the data on the first 25,000 cases in Wuhan. They fit a standard mathematical model to the epidemic, something that is pretty well understood and well-accepted in the field (Evolving Epidemiology and Impact of Non-pharmaceutical Interventions on the Outbreak of Coronavirus Disease 2019 in Wuhan, China. Chaolong Wang and others, medRxiv preprint doi:
https://doi.org/10.1101/2020.03.03.20030593).
They calculated that, in the early days, before Chinese New Year and before anything was being done to stop it, each new case infected approximately 3 people. This is a statistic called the basic reproductive number, and it’s not hard to understand what it means: the disease will spread at an ever-accelerating pace as the number infected triples every incubation period, which is around 5 days. Yikes.
But, the good news is that by mid-February, after aggressive quarantine, tracing of contacts of infected cases, and rather severe social distancing measures, the basic reproductive number fell to about 0.3. When this number is less than one, it means that the epidemic is dying out, that new cases don’t reproduce themselves.
The authors estimate that, if their model is correct and conditions continue as they were in late February, there will be no new cases in Wuhan, population 10 million, by the end of April or early May. How far behind Wuhan are we? We don’t know, but perhaps, if the country stays the current course and follows strict isolation policies, then perhaps we aren’t that far behind. With luck.
There’s another interesting finding in the paper. Making certain assumptions about how an epidemic works, they could estimate how many cases there were in Wuhan who never came to attention; they were either completely asymptomatic or mildly symptomatic. They were never tested, etc. The authors estimated that at least 59% of infected cases were never identified. This means a couple things. First, it is likely that these people were infectious, for some days, passing the disease to others, while going about life as “healthy” people. So, this is one reason why social distancing is so important. But another important implication is that the disease is moving through the population, changing people from “susceptible” to “immune” without having to pass through “sick”. In the long run, this is how this story resolves; the population will become largely immune. Some will die (perhaps as many as 1% of those who are infected, although heavily concentrated in frail elderly), some more will get sick, survive and become immune, while others – and their data suggest a majority -- will become immune asymptomatically. New generations will probably face the risk anew, but hopefully a vaccine will come soon, to help them out.
So, think of the next few weeks this way: you are protecting yourself from getting sick, but just as importantly, you are participating in a collective action to drive down the spread of the disease, protecting many many others whom you do not know, but who should thank you for helping them to stay healthy.
I’ve spent my entire career waiting for the word “epidemiologist” to be uttered on late-night TV, and now that we’re here, I realize it’s another case of “be careful what you wish for”.
I hope this helps. Stay safe!
Love, David
Here is the response on the above from the retired CEO...
I like this analysis. It is clear and a reasonable treatise.Two things that are not in his analysis are the mutation rate of the virus, and second and third waves of infection. These are probably related. When we were developing AIDS drugs, we found a single drug would knock down the viral load for about 6 months, then mutation let the virus escape. That is why patients are treated with a cocktail of three drugs today. Took us 10 years to get things right. And, today both Singapore and Hong Kong are reporting a growing second wave of infection... Not good.. In the end, what we are being asked to do, self isolate and sanitation are our best tools. Again, if you need help running errands, Paula and I are available.., Stay safe.
