At the conclusion of a meeting in Geneva on how to limit the effects of a future flu pandemic, experts remain divided on the chance of success.
The World Health Organisation (WHO) brought together 30 international specialists this week in order to revise its draft "containment strategy".
The WHO had hoped to be able to produce a version ready to be put into action with the aim of halting the initial spread of any future flu strain that is transmissible between humans by using a "fire blanket" of antiviral drugs given to treat everyone in the area around an infection outbreak.
Margaret Chan, the officer in charge of WHO's influenza response, believes collective action is the best defence.
Chan's view of the benefit of containment has gained support from two different scientific models by UK and U.S. academics, which simulated an outbreak in Thailand.
They both believe that containment could work under certain conditions and differ only when it comes to levels of doses of antivirals needed to succeed in controlling the spread of the virus.
They do at least offer, for the first time, some hope that a flu pandemic could be held in check, rather than spreading uncontrolled around the globe.
However, other experts are less optimistic and say the probability of successful containment is slim and even if one localised outbreak were stopped, others are likely to follow, requiring large volumes of antivirals to be used each time.
The WHO says that even if a pandemic cannot be stopped, public health interventions might buy time to allow countries to further strengthen their response systems, as well as accelerating the production of pandemic vaccine.
Meanwhile the Austrian cat which has twice tested positive for the H5N1 bird flu virus has now tested negative, adding even more uncertainty about bird flu and cats.
The cat was one of 170 that were kept in an animal sanctuary in southern Austria close to a cage of fowl which had been infected with H5N1.
Initially three cats tested positive for the virus in saliva tests last week, now all are said to be free of the virus.
Blood test results are still being done but it appears cats are more resistant to the virus than chickens.
The WHO says more studies are needed on infections in cats, including how they shed the virus in their environment.
They have requested more details on the cats, and say it is potentially significant that animals could contract the virus and not show any symptoms of illness.
Bird flu can wipe out poultry flocks in the space of 48 hours and can also infect people who come into close contact with infected birds.
It remains a disease of birds but has killed at least 95 people in Asia and the Middle East since late 2003 and caused millions of birds to be slaughtered.