“High Contagiousness and Rapid Spread of Severe Acute Respiratory Syndrome Coronavirus 2,” CDC, Emerging Infectious Diseases
Doing my usual morning reading, I ran across a comment concerning an early release article by the CDC which as the CDC points out is not considered to be a final versions. I believe what is important about the preliminary information is the increase of R-naught from 2.3 to 5.7. By now I believe you know what R-naught means; but, I will repeat it anyways. R-naught reflects the potential number of people who are infected by one contagious person. The abstract also emphasizes continued active surveillance, contact tracing, quarantine, and early ‘strong’ social distancing efforts are needed to stop transmission of the virus.
Meanwhile our president wants to open up the country come May as some states have just started to initiate “stay at home” policies, and other states have yet to implement stay at home policies. Our leaders Washington D.C. are also pushing “herd immunity” which I believe is influencing our president’s desire to open up for business come May. A post by Yves Smith at Naked Capitalism develops the theory of “herd immunity” as briefly explained by one of the NC readers;
“The herd is allowed to be infected and then observed the course of the disease. Those left are either immune to the disease or robust enough to fight off the infection. This immunity of course applies only to the given pathogen and can’t be easily generalized. This is not usually a strategy adopted for human beings.
The term is usually used in the context of the introduction of a vaccine where you are creating, to the extent you can, herd immunity. You then observe how well the vaccine works. If the vaccine works, you have created herd immunity for a certain period of time, a period associated with the pathogen and the immune system’s response to it. It will be different for each pathogen. For standard flu, it appears to be about a year. For covid-19, no one seems to know.”
Dominic Cummings, the promoter of herd immunity in England has come down with Coronavirus and has of yet has not returned to Downing Street after quarantining himself a week ago. That is as it should be, if a countries leader is to promote herd immunity to open an economy or keep an economy open as he did, they should lead the way and set the example for the rest of the herd. Dominic Cummings is a Boris Johnson advisor. It is doubtful we shall see many of our leaders lighting the way for us as examples.
In any case read the abstract (after the leap) and view the chart I posted. There is more information and charts in the article itself which will shed more light on the Coronavirus.
Abstract: Severe acute respiratory syndrome coronavirus 2 is the causative agent of the 2019 novel coronavirus disease pandemic. “Initial estimates of the early dynamics of the outbreak in Wuhan, China, suggested a doubling time of the number of infected persons of 6–7 days and a basic reproductive number (R0) of 2.2–2.7. We collected extensive individual case reports across China and estimated key epidemiologic parameters, including the incubation period. We then designed 2 mathematical modeling approaches to infer the outbreak dynamics in Wuhan by using high-resolution domestic travel and infection data. Results show that the doubling time early in the epidemic in Wuhan was 2.3–3.3 days. Assuming a serial interval of 6–9 days, we calculated a median R0 value of 5.7 (95% CI 3.8–8.9). We further show that active surveillance, contact tracing, quarantine, and early “strong” social distancing efforts are needed to stop transmission of the virus.