The influence of Factor X on the progress of the epidemy
It is very interesting trying to reconstruct the epidemy progress not only from the curve of daily new cases, but also from the number of new hospitalized patients. The curve of new hospitalized cases may be quite easily calculated from the number of hospitalized patients, the curve of patients being released from the hospital and the curve of death cases. Strictly said, we would need the curve of death cases from hospitals only, which are not available, but this value may be quite well estimated by all death cases. It may be expected, that most Covid-19 deaths happens in the hospitals, while the nubmer of death cases outside of hospitals is marginal. The reconstructed daily new hospitalized patients curve looks like this:
According to the daily new hospitalized cases one may estimate the R number, generally according to the same algorithm like it is estimated in daily new infected cases. It can be expected, that both reproduction numbers calculated using these two methods should be shifted to each other a couple of days, but theoretically they should be the same. In reality, both reproduction numbers look like this:
It may be observed in the graphs that both reproduction nubmers are matching each other quite well. A variable time shift between both numbers may be observed. The variability may be attributed to the delays in testing of new cases, which are at the end of october 2020 so delayed, that hospitalizations have no delay behind the testing of new cases. However, the fact that both reproduction numbers match each other pretty well means, that the procedure of testing new cases is still pretty well-predictive. Maybe it is a bit useless since it could be replaced by calcualtion from new hospitalized cases, but it definitely works.
But much more interesting is the fact, that at the turn of September and October there is a significant decrease of the reproduction number of the firus, which is followed by rising again in the second week of October. Moreover, this hop may be observed on both reproduction numbers. This hop cannot be explained by the goverment measures and also not by the behavior of the people. It is simply not imaginable, that the level of responsibility of people towards the epidemy and towards fellow citizens would fluctuate so much. Therefore it may be said, that there was a mysterious Factor X acting at the turn of September and October, which decreased the reproduction number of the virus at least by 0.33, which is by the absolute value of the reproduction number 1.5 to 1.6 more than 20%.
Only speculations can be made, what is this mysterious Factor X. It could be something related to the weather (but looks like some very non-standard component of the weather), maybe there could be some psychosocial regularities, which we don't realize too much and which may significantly influence the human immunity. Anyway, it should be considered, that significant influence to the epidemy spread is given by factors, we know absolutely nothing about.
