Four volunteers involved in the world's first clinical testing of a vaccine for severe acute respiratory syndrome (SARS) are in good condition, sources with the Sino-Japanese Friendship Hospital announced Wednesday, May 26.

On the afternoon of May 22, the four volunteers, including three healthy male students and a female from Beijing-based universities, were injected with a SARS vaccine or a SARS virus-free placebo at the hospital.

The 72 hours after the test no adverse reactions were shown among any of the four volunteers, according to the just-publicized observation result, which became the initial outcome of the world's first clinical testing of a SARS vaccine.

The testing was chaired by Prof. Lin Jiangtao, head of the Respiratory Medical Department with the Sino-Japanese Friendship Hospital.

The volunteers took blood tests and were observed for reaction daily in the first three days, and the whole observation process will last 210 days, according to the hospital.

The four are the first group of 36 healthy volunteers aged from 21 to 40 who were selected for the testing.

Approving the first phase of the clinical testing in January this year, China has become first nation in the world to approve clinical testing of the vaccine on humans.