Approximately 43% of the index case-patients were women; the median age was 20 years, and 38% likely contracted pandemic (H1N1) 2009 virus locally because they had not traveled recently. Among the index casepatientss, 2% had subclinical infection. Only 18% of index case-patients had close contacts with confi rmed pandemic (H1N1) 2009 (Table 2) , and the total number of close contacts who were infected by the virus from 110 index case-patients was 167.