There’s a lot being written about COVID-19, the new coronavirus, maybe too much in my opinion. There’s a lot that can be said about China’s political reaction to the virus, although even there we are at the beginning of things, and there’s a lot we don’t know.
I read a short and well-written article last night in Science magazine. It got me thinking about what I’m looking for in news about the virus. The mathematics of disease transmission are similar to the mathematics of chemical kinetics, which was part of my life as a chemist. That’s where my questions originate.
There is no evidence that the virus was generated as part of a biological warfare program. Its DNA has been sequenced, and there would be clues there if that were the case. It most likely originated in bats, as has been true for other coronaviruses, and was transmitted through another animal in a live-animal market. Tom Cotton lies; but we knew that.
We know very little of the parameters that are necessary to predict how widely the virus will spread or how dangerous it will be. Epidemiologists are collecting data, but the parameters depend on statistics that we need more of or time-consuming laboratory work that may be hard to carry out while treating sick people is the first priority.
- How many cases are there? Some cases have been carefully diagnosed with appropriate laboratory tests. The reported number shot up during the past week when China loosened the criteria for reporting. Some people may be infected without symptoms or may have minimal sniffles and may not be counted. This website from Johns Hopkins gives confirmed cases, deaths, and recoveries.
- How contagious is the virus? This is represented by R0, the measure of how many people one person with the virus infects. We don’t know whether the virus is contagious before people show symptoms. We don’t know how long the incubation period is. R0 is derived from observations, so it is likely to change as more information comes in. I have seen a wide range of estimates for R0.
- What happens to the virus as the seasons change? Some common cold viruses, including coronaviruses, become less infective as the weather warms in spring. But not all coronaviruses, and we just don’t know about this one.
Every day, there is more information available, but I doubt there will be a reliable R0 for some time. Each case can provide a bit of data – I particularly hope that good records are being kept on that cruise ship in Japan.
James Palmer is a good Twitter follow on the subject for the big picture. He’s lived in China.