The notion of resorting to untested and experimental drugs against a lethal epidemic sounds like germ-warfare fiction. It is not something the World Health Organisation or other authorities would normally approve lest it does more harm than good. In the worst outbreak yet of the lethal Ebola virus, the WHO has made an unprecedented exception by endorsing treatments with unknown efficacy and side effects - because there are no others.
Ebola outbreaks have been contained for nearly 40 years. Now it has jumped borders and spread to urban areas of West Africa. The fact that the WHO has declared an international emergency reflects how little progress has been made in combating it.
A small US company has sent its supplies of an experimental serum - ZMapp - to Africa after two infected Americans, a doctor and an aid worker, improved following treatment with it in the United States. So far, there is only evidence that it did no harm. It is one of a number of potential anti-Ebola drugs and vaccines yet to undergo clinical testing that may be made available to patients subject to informed consent. There is an argument for giving priority to doctors and nurses who risk their own lives to try to save patients. Governments, international agencies and the pharmaceutical industry must combine to fast-track clinical trials of treatments and vaccines.
Meanwhile, infection control measures and expert medical care offer the best hope of containing the epidemic. In that respect, the controller of the Centre for Health Protection, Dr Leung Ting-hung, has admitted that the city's first suspected Ebola case could have been handled better, after health workers did not wear special protective gear. That was not to be expected after the 2003 severe acute respiratory syndrome outbreak, during which the effectiveness of protective gear was an issue that had to be addressed. The patient, a Nigerian, tested negative, so no harm was done. But the incident serves as a reminder that we cannot relax our vigilance.