Ho risolto rispolverando la Cache
in un modulo ho messo:
codice:
Imports Microsoft.VisualBasic

Public Module CacheFunzions
    'salva il riferimento all'oggetto Cache
    Dim Cache As System.Web.Caching.Cache = HttpRuntime.Cache

    Public Sub CacheStatisticheCOVID19()
        Dim s1 As String = "" 'dati ultimi province
        Dim s2 As String = "" 'dati storici province
        Dim url1 As String = "https://raw.githubusercontent.com/pcm-dpc/COVID-19/master/dati-json/dpc-covid19-ita-province-latest.json"
        Dim url2 As String = "https://raw.githubusercontent.com/pcm-dpc/COVID-19/master/dati-json/dpc-covid19-ita-province.json"

        Try
            Dim wc = New System.Net.WebClient()
            s1 = wc.DownloadString(url1)
            s2 = wc.DownloadString(url2)

        Catch ex As Exception

        Finally

        End Try

        Cache.Insert("covid19_province_ultimi", s1, Nothing, DateTime.Now.AddHours(1), Cache.NoSlidingExpiration, Caching.CacheItemPriority.Default, AddressOf OnRemoveItem)
        Cache.Insert("covid19_province_storici", s2, Nothing, DateTime.Now.AddHours(1), Cache.NoSlidingExpiration, Caching.CacheItemPriority.Default, AddressOf OnRemoveItem)

    End Sub

    Private Sub OnRemoveItem(key As String, value As Object, reason As CacheItemRemovedReason)
        'aggiorna sembre la cache
        CacheStatisticheCOVID19()
    End Sub
End Module
Nel Global.asax:
codice:
Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
    Application.Lock()

    'leggo le statistiche covid-19
    CacheStatisticheCOVID19()

    Application.UnLock()

End Sub
Mentre nel file che mostra le informazioni:
codice:
Dim s As String = NullToString(Cache("covid19_province_storici"))