April 26, 2006. Copyright, 2006, Graphic News. All rights reserved

Combination treatment -- best way to tackle flu pandemic

LONDON, April 26, Graphic News:  Rapid treatment and isolation of not just infected cases but also their household contacts will be the key elements of an effective strategy to head off a potential influenza pandemic, report researchers who have simulated the spread of such an outbreak in both Great Britain and the United States.

In an article in the latest issue of the journal Nature, Neil Ferguson of Imperial College, London, and Derek Cummings of Johns Hopkins in Maryland suggest that governments should hit the deadly H5N1 virus with a double whammy if the bird flu virus mutates into a human form.

The study says governments should stockpile sufficient antiviral drugs for at least 50 percent of their populations -- twice what many countries are planning -- and these drugs should be used with a trial vaccine, even if the vaccine has low efficacy. In addition, household quarantine, school and workplace closure, border controls and travel restrictions should be enforced with virtually no exceptions.

Neil Ferguson and colleagues used state-of-the-art computer models to evaluate the influence of a range of anti-pandemic measures. They show that a strategy of giving antiviral drugs both as treatment to infected cases and prophylactically to their families coupled with early closure of schools hit by the outbreak, could cut rates of disease by nearly half.

Combining such a policy with targeted immunization of children with a stockpiled trial vaccine might reduce illness rates by two-thirds, even if the vaccine was not particularly effective in its protection.

The recent spread of avian flu to developed countries -- including 14 in the European Union -- and the fact that bird flu is almost certainly being spread by migratory birds, means that by the end of 2006 there will be avian flu in birds on every continent.

According to the World Health Organization (WHO), of a total of 204 people who have contracted the H5N1 virus, 113 have died. The WHO suspects that most of those people had direct exposure to infected poultry.

ÒNo one will have immunity should an H5N1-like pandemic virus emerge,Ó the WHO notes on its website. This fear has spurred drug companiesÕ efforts to search for new weapons against flu viruses.

One new antiviral drug, Peramivir, made by BioCryst of Birmingham, Alabama, has started U.S. human clinical trials. Peramivir is a neuraminidase inhibitor, which means it is in the same drug class as Swiss drugmaker RocheÕs Tamiflu and GlaxoSmithKlineÕs Relenza, the two licensed antiviral drugs currently being stockpiled around the world.

Sanofi Pasteur of France and U.S. drug maker Chinon both have a vaccine -- produced from an inactivated H5N1 virus -- in clinical trials for the National Institute of Allergy and Infectious Diseases (NIAID).

In Canada, the Public Health Agency plans between 25 million and 30 million doses of a made-at-home vaccine produced by GlaxoSmithKlineÕs vaccine plant in Quebec.

However, complicating planning are recent reports that the trial vaccines require massive doses -- two shots of 90 micrograms apiece, equivalent to 12 times the amount needed to protect against seasonal flu strains -- to induce a protective response, and then only in just over half of people who received the largest dose. If this dose canÕt be decreased, the current U.S. stockpile only has enough vaccine for 4 million people

Ferguson et al. point out that their computer model applies only to a ÒtypicalÓ strain of human influenza. If H5N1 mutates into a human form it might be easier to control, the authors say.

This hope is echoed by Dr. Anthony Fauci, head of NIAID. ÒIt is entirely conceivable that this virus is inherently programmed [and] will never be able to go efficiently from human to human,Ó Fauci said.

ÒHopefully the epidemic [in birds] will burn itself out, which epidemics do, before the virus evolves the capability of being more efficient in going from human to human.Ó
/ENDS