immunization is not something your body obtains forever - might only be a few months. If the spread is too slow we'll never reach immunization. Instead the viru

immunization is not something your body obtains forever - might only be a few months. If the spread is too slow we'll never reach immunization. Instead the virus will take its rounds repeatedly infecting people. Also the 60/70% figure assumes an R0 of about 3. It seems though that it is >5. Then you would need a herd immunization of >80%.