The World Health Organization (WHO) issued a step-by-step plan on Tuesday, including the rapid mass use of the antiviral Tamiflu, for containing a bird flu outbreak if the virus starts to spread rapidly among humans.
The “rapid response and containment strategy” has a chance of quashing the deadly H5N1 virus only if people in the zone at risk receive massive doses of the drug within three weeks of a confirmed outbreak, it said.
“The success of a strategy for containing an emerging pandemic virus is strictly time dependent,” the WHO said in its latest containment report, based on recommendations by 70 international experts who held closed-door talks in March.
“Mathematical models have indicated that a containment strategy, based on the mass administration of antiviral drugs, has a chance of success only when drugs are administered within 21 days following the timely detection of the first case representing improved human-to-human transmission of the virus.”
Under the detailed timeline laid down, a country should notify WHO of a cluster of suspicious cases suggesting sustained human-to-human spread of the virus within 24 hours of detection.
A WHO-approved laboratory has another 24 hours to confirm that the H5N1 bird flu virus has changed, either through mutation or through reassortment with human influenza.
The strategy relies on WHO’s global stockpile for rapid containment, three million treatment courses of Tamiflu, donated by Swiss drugmaker Roche. Quarantine, infection control measures and contact tracing must also be carried out.
Once the WHO officially asks Roche for Tamiflu doses to be sent, they should arrive at the international airport nearest the outbreak within 24 hours, the Geneva-based agency said.
The WHO said on Saturday that it had for the first time asked Roche to be prepared to ship Tamiflu to Sumatra, Indonesia, where a family of seven was infected, with possibly some limited human-to-human transmission.
In the end, the WHO did not ask for the drugs to be sent.
“If we needed to mount a containment effort, we needed to be sure that Roche would be ready,” WHO spokeswoman Maria Cheng told a briefing on Tuesday.
Alert phases
The WHO also said on Tuesday it was refining its guidelines for a global influenza pandemic alert to make them clearer.
Nervous financial markets were shaken last week by talk that the WHO was about to raise its level of alert from its current three on a six-point scale after the Sumatra cases.
There was concern that the spread of the H5N1 virus among the family members indicated that it was becoming better at infecting people.
But the WHO subsequently said tests showed that there had been no significant genetic changes and that the virus had not become more dangerous to humans.
The revised guidelines, expected to be issued in a few weeks, will try to use language that is “more acceptable (and) understandable,” Cheng said.
Level three means some very limited human-to-human transmission of bird flu has occurred, while level four signals evidence of increased human-to-human transmission.
Phase five would signal evidence of “significant human to human transmission,” while six would signal the onset of a pandemic, which the WHO has warned could take millions of lives.
Bird flu remains essentially an animal disease, but it has taken 127 lives among 224 cases in 10 countries since 2003.
The WHO considers Tamiflu the frontline drug against the H5N1 bird flu strain, but says more clinical studies are needed.