Tuesday, May 4, 2021

India's Second Wave, part 2


1.    Second Wave

  Small samples of corona virus from Maharashtra and Punjab have been tested for DNA to determine whether new variants of the original virus have started spreading. These show that the proportion of the double mutant version of the corona virus has increased over a few months. IA similar increase in the UK mutant of the virus has been found in Punjab. Given that that all States have the same pattern of decline in cases, followed by the start of a second explosive growth of cases of corona virus infection, we hypothesis that the second wave has been caused by the arrival of new mutations in India. I time series of the potential new mutants is created by assuming that the original version of the corona virus continues to spread at lowest growth rate observed and that any additional growth of cases after the trough, is attributable to the new mutations. An S-curve is then fitted to this constructed series and used to project the cases forward. The results for are summarized in the first two and last two columns of Table 2, with estimated model parameters in the middle four columns.



   The States can be divided into three sets, depending on the month of the break out. Maharashtra and Punjab corona explosion occurred in February along with Tamil Nadu and Karnataka. Gujrat, Madhya Pradesh Delhi and Rajasthan, epidemic exploded in March, while that of UP, Bihar, west Bengal and Kerala started in April. The most accurate predictions can be made of the States in which there is most data, i.e., those whose second wave exploded in March, so we have focused on modeling those. Thus we predict total cases to peak at 23 million in first half of June, with 5 mi in Maharashtra, 1.6 mi in Tamil Nadu, 1.2 mi in Delhi and 1.5 mi in Utter Pradesh (last 2 columns of table 2).

 Figure 4 shows the graph of the S curve fitted to the assumed estimate of the cases having the mutated virus. The purpose is to project these forward, recombine them with the projected spread of the original virus to get an estimate f total cases in May and  June. Figure 5 shows the graph for Maharashtra, indicating that the number of cases in Maharashtra is likely to plateau out innext two weeks. All the other States shown in Table two, have a similar evolution of new cases and the S curve for new cases.


 New V (est) = Total cases – Cases estimated on assumption that the original virus continues to grow at the rate prevailing at the trough. New V frcst is the forecast made on the basis of the S curve fitted to “New V (est)”; R square of fitted curve with 3 parameters is 0.9965.


 part 3.......


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