How to calculate the Rt reproduction number in your state, and why I don't expect peak in Russia before June 18

   During the first 3-4 weeks, the infection develops according to the classic scenario when the number of infected is easily calculated using the geometric progression formula. For Chinese flu, R0 (basic reproduction number) is 2...3, and the serial interval (the time between infections) is 5 days. Then the quarantine comes into effect, the number of patients who have been ill increases, and  Rt statistical number is used to assess the epidemy.
According to the Rospotrebnadzor (Russian Federal Service for Surveillance on Consumer Rights Protection) methodology, the Rt infection rate is an indicator that determines the average number of people infected by one patient before isolation. The Agency focuses on the regions on the transition to the I phase of the lifting of restrictions at a rate of less than 1.0; II phase - if Rt  is below 0.8.
   Is it possible to calculate this mysterious reproduction number in your state? Last Sunday I finally got to the Rospotrebnadzor manual and now I am happy to share its secret formula with the audience of my blog.

 

X1 ...X8  number of new cases a day. Rt =(X5+X6+X7+X8)/(X1+X2+X3+X4)

Now let's look at the dynamics of Rt in the US and in Russia. Day zero was taken when the number of cases exceeded 50. The comparison is particularly useful because the development of infection in America is 17 days ahead of Russian history. And if the Russian statistics is not very false, then we can predict what will happen in the next 2-3 weeks.

Rt in Russia and the US . X  axis -  days since the beginning of epidemic in the country.

The 7-day cycle of the Rt  in the US and its absence in Russia is immediately noticeable, but otherwise the indicators of development of infection  behave like twins. So, we can project that Russia is unlikely to reach the peak of epidemy before June 18.