A 22-year-old male patient from Qinhuangdao city is currently studying at a university in Melbourne, Australia. At 9:50 AM (Sydney time) on June 18th, he boarded flight CA178 from Melbourne, Australia and arrived in Shanghai at 7:30 PM (Beijing time) on the same day. At midnight on June 20th, he boarded flight CA176 in Shanghai and arrived in Beijing at 2:30 AM. His father then picked him up by car and returned to Qinhuangdao. In the afternoon of June 20th, the patient began experiencing symptoms such as headache, coughing, sore throat, sneezing, and runny nose. On the evening of June 21st, he felt feverish; his temperature was 37.5℃ in the morning of June 22nd. That day at 11:00 AM, he sought treatment at the fever clinic of the Haigang Hospital in Qinhuangdao. His temperature was measured at 38℃ and he was immediately transferred to a designated hospital (the Third Hospital of Qinhuangdao) for isolation and treatment. Samples were also taken and sent to the laboratory for testing. On June 23rd, both the Qinhuangdao and provincial Centers for Disease Control and Prevention successively reported positive results for the H1N1 influenza A virus nucleic acid test.