SARS-CoV-2 is a new virus in the human ecosystem. Humans didn’t pay much attention to it when it was only in bats. It’s of great interest to humans now. Because it’s new to our bodies and societies, we know nothing about it. We are picking up empirical observations quickly, but it’s hard to put them together in real time, motivated by sickness and death.
Research is proceeding, particularly for testing methods for both the virus and human immunity to it, for a vaccine, and for treatments. Many questions are still open. We will hear bits and pieces from the research, but the bigger questions won’t be answered for some time. Read More
The best case would be R < 1 and herd immunity >70%.
R is the reproduction number, the number of cases that one case causes. R0 is the basic reproduction number, which is an idealization of how a disease spreads in a given population. Reff is a measured number for a particular situation. In looking at the models, I see R0 being used in ways that look like it contains other parameters as well. So I will just use R, which is the same as Reff. Using it without a subscript and the context will, I hope, indicate that it is totally situational. Read More
We are now isolating ourselves, at least the non-MAGA portion of the population. The numbers of cases of Covid-19 – and deaths – are mounting. What can we expect? What happens next?
Lots of us are wondering what comes next in the SARS-CoV-2 pandemic. We already have an indication in New York City. At the same time, many states and countries are instituting lockdown measures that should decrease the numbers of sick and dead. I’ll use the Imperial College paper to discuss what is likely to come next. Read More
The Imperial College study, “Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand,” from the Imperial College COVID-19 Response team, is said to have influenced both the United Kingdom and the United States governments.
It models how the SARS-CoV-2 virus and its resulting disease, COVID-19, might spread through those two countries. The numbers of cases of COVID-19 and resulting deaths are high, as are the amounts of time predicted necessary for social distancing. It looks at interventions that can bring the numbers down or spread them out in time.
All models are wrong, but some are useful, it is said. It can be misleading to simply take those bottom-line numbers, though. What models are good for is looking at what changes can be put into the system and which are most important. Read More
Most of the general information I’m seeing on SARS-CoV-2 and COVID-19 is good! I’m pleased not to be complaining about it for a change. There’s one part of the information flow that needs qualification, though.
That genre is the scientific paper. Scientific papers and Twitter threads from scientists often require interpretation. What I’m seeing now is that articles by reputable science journalists are a better guide to what we know than individual papers or threads. Read More
As I’m trying to dig out the problems with SARS-CoV-2 testing the United States, it’s become necessary for me to learn a bit about how the test works. I am not an expert in RNA analysis, but this is chemistry, which I do understand. I asked Stephen N. Floor, Assistant Professor in the Department of Cell and Tissue Biology at the University of California, San Francisco, some questions and to check my work. All errors and political content in this post are mine.
We still don’t know why the CDC decided to develop its own test for SARS-CoV-2. If the dysfunction persists, it’s a danger to other decisions being made about the epidemic. But, like the number of Covid-19 cases in the United States, we just don’t know.
The director of the CDC, Robert Redfield, was involved in the decision, but we don’t know how. It could be anything from a definitive order to passing it off to someone else, which is a decision too. Read More