Due to the confirmation of China's first swine flu case by the Ministry of Health, authorities are urging all passengers onboard May 8's Northwest Airlines flight NW29 (Tokyo-Beijing) to contact their local center for disease control and prevention or other relevant public health agencies.

Despite the best efforts so far, while most passengers who shared the same flight have been tracked down by health authorities here in China, but authorities are still experiencing difficulties in locating the few remaining passengers.