Cluster A comprises 61 cases (54 of a total of 2,453 cases residing in Lower Austria) and includes 6 case generations.
The primary case (case 1) residing in Vienna had symptom onset on 02/23/2020 and a travel history to Milan, Italy, within the 14 days prior to his symptom onset. Case 1 is by definition an imported case from which a local transmission chain originates (i.e., travel-associated local cluster).
AGES, Department of Infectious Disease Epidemiology