Variant forecast taking into account the presence of the Delta variant

We present a variant forecast for spreading of the epidemic by the end of August. Due to the fact that the used version of the model does not yet take into account the risk of reinfection, both variants of the forecast assume a lower level of population immunity – the percentage of survivors in the population on June 1 is approximately 45%.
The variants differ in the assumed level of participation of the Delta variant in new infections on June 1.

We assume that each approved age group will no longer get vaccinated once vaccination coverage is reached at 70%. The assumed vaccination efficiency is the same for all variants.

We consider two levels of the Delta variant in new infections on June 1: 3%, 6%.
This translates into the share of the delta variant in mid-July, respectively 60% and 75%.
The relative infectivity of the variant Delta with respect to the variant Alpha is taken as the relative infectivity of the variant Alpha with the wild-type variant.
The virus variants in the model are characterized by relative infectivity. Relative infectivity is understood as a value that describes the biological characteristics of a virus that affect the rate of host cell colonization.

The forecast takes into account all historically introduced restrictions and loosening, including the holiday period (school closings and increased travel).

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