THE SARS virus has escaped from a high-containment research lab for at least the third time, causing an outbreak in China. The escapes suggest that the 鈥淏SL-3鈥� level of biological containment used for SARS is either not being applied correctly in many labs or cannot contain the virus. This raises concerns about other viruses handled in a similar way.
A graduate student who worked for two weeks at the Institute of Virology of the Chinese Center for Disease Control in Beijing developed SARS on 25 March, and a postdoc in the same lab fell ill on 17 April. The timing suggests the pair were exposed on separate occasions.
In two incidents last year, SARS researchers in BSL-3 labs in Singapore and Taiwan also developed the disease. But while quick quarantine in those cases prevented the disease spreading, the Beijing student, a 26-year-old woman named Song, was not isolated until it was too late. She infected her mother, who died, and a nurse. Three members of the nurse鈥檚 family, and Song鈥檚 doctors, now have symptoms. More than 600 people had been quarantined by 27 April.
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While she was potentially infectious, Song also travelled back and forth between Beijing and her home province of Anhui. Officials have alerted passengers on four trains.
Although Song did not work with SARS directly, under BSL-3 rules any such illness in a lab worker should have been investigated at once. The Beijing lab has been sealed pending investigation by the World Health Organization. 鈥淎ccidents can always happen. But four accidents in a period of eight months? That has to raise some alarm bells,鈥� says Donald Low of Mount Sinai Hospital, Toronto, who led Canada鈥檚 fight against SARS.
This run of escapes suggests that BSL-3 may be risky for viruses that can infect lab workers. SARS is not even the easiest to catch. Experiments to see what changes make the bird flu virus more contagious in humans, and to partially reconstruct the 1918 flu virus, are being carried out at a similar level of containment (New 杏吧原创, 28 February, p 4).