Friday, November 27, 2020

Covid: Cases vs Deaths

News stories keep reporting record numbers of cases but not record numbers of deaths. Santa Clara County, where I live, shows detailed information on both, and the divergence is striking: Looking at the graphs, the case rate began to climb rapidly about a month ago, the death rate appears to be holding roughly steady. We would expect deaths to lag cases, but not by a month.

The divergence is less striking in the U.S. figures, but it's still there. Roughly speaking, over a period when case rates are more than tripling, death rates are doubling. I don't have the data in a form that would let me do a more precise comparison, but that seems to be the pattern so far.

Three possible explanations occur to me. One is that we have more testing, with the result that more of the milder cases are being spotted. If so, the reported increase in cases exaggerates the real change. A second is that we have gotten better at treating Covid, which would be good news but consistent with the increase in cases being real. A third is that fewer of the patients are old. Has anyone here spotted an analysis of the data that can distinguish among those alternatives? 


Anonymous said...

I can think of three other explanations:

1. The virus is mutating to become less virulent.
2. The virus has killed off those more vulnerable to its effect, and is now attacking more robust individuals.
3. The methodology or standards for measuring cases is different than it was historically.

Anonymous said...

Also the cases now may be less virulent because the social distancing that people due reduces the exposure that infects them, which might make the infection less serious.

Tom Bridgeland said...

Our treatments are somewhat better. For example, in the early days we did not routinely give anticoagulant drugs like Lovenox. Once we started doing that, severity decreased.

Also, early Chinese data told us that using steroids was a bad idea. Now we have better data and routinely give Decadron. We also are giving zinc, vitamin D and C, which may be helping. Pretty much we ignore any information or scientific papers coming out of China as either fraud or deliberate misdirection.

One thing I see as a nurse is that we are far more skilled at identifying those patients who are not doing well and getting them treatment quickly. In the early days it was a shock to see how quickly patients went into decline, and there was a significant lag as we tried to figure out if they warranted more intense care. Now we know, and respond immediately, and the doctors know how to respond when a frantic nurse pages them.

Tom Bridgeland said...

We are still seeing a fair number of cases from nursing homes, but nothing like in the initial surge. Either the homes are protecting their patients better, or the vulnerable ones have already gone through the wringer.