(* Get COVID-19 data *)
RetrieveCovidData[type_]:=Import["https://github.com/CSSEGISandData/COVID-19/raw/master/csse_covid_19_data/csse_covid_19_time_series/time_series_covid19_"<>type<>"_global.csv","CSV"]
infected =RetrieveCovidData["confirmed"];
death=RetrieveCovidData["deaths"];recovered=RetrieveCovidData["recovered"];

(* Data preprocessing, country selection *)
GetCountryData[country_]:=(countries=Map[#[[2]]&,infected];i=Position[countries,country][[1,1]];Join[{infected[[1]][[5;;]]},#]&@Map[#[[i]][[5;;]]&,{infected, death, recovered}])
(* Get data for country and remove days without infection *)
GetPrunedCountryData[country_]:=(
{date, i, d, r} = GetCountryData[country];
firstOccurence=Position[i,Select[i,#>0&][[1]]][[1,1]];
Echo[date[[firstOccurence]],"First seen in "<>country<>": "];
Map[#[[firstOccurence;;]]&,{date,i,d,r}])

{date,iCZ,dCZ,rCZ}=GetPrunedCountryData["Czechia"];

ListLinePlot[iCZ,PlotStyle->{Red,Dashed}]

0=lnI(0)+((Subscript[R, 0])-1)t*a-lnI(t)

(Subscript[R, 0])=Nr/a

diCZ=Map[Log,iCZ];

GetR0[di_,a_,t_,range_]:=(di[[t]]-di[[t-range]])/((range+1)*a)+1//N

GetGraph[range_,params_]:=ListLinePlot[#,PlotStyle-> params]&@Table[GetR0[diCZ,1/10,i,range],{i,range+1,Length@diCZ}]

g1=GetGraph[6,{Red,Dashed}];
g2=GetGraph[10,{Blue,Dashed}];

Show[g1,g2]