Travel bans won't stop bird flu - study

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Travel bans won't stop bird flu - study April 04 2006 at 07:47AM

By Maggie Fox, Health and Science Correspondent

Washington - Travel restrictions and school closures will do little

to stop a pandemic of bird flu from marching across the United

States, but they may slow it enough to distribute drugs and vaccines,

according to a new study published on Monday.

" It's probably not going to be practical to contain a potential

pandemic by merely trying to limit contact between people such as by

travel restrictions, quarantine or even closing schools, " said

Germann of Los Alamos National Laboratory in New Mexico, who

worked on the report.

" But we find that these measures are useful in buying time to produce

and distribute sufficient quantities of vaccine and antiviral drugs. "

Their study, published in the Proceedings of the National Academy of

Sciences, supports the approach being pursued by the US government

and recommended by the World Health Organisation for preparing for a

possible influenza pandemic.

" Our model suggests that the rapid production and distribution of

vaccines, even if poorly matched to circulating strains, could

significantly slow disease spread and limit the number ill to less

than 10 percent of the population, particularly if children are

preferentially vaccinated, " the team at the US Department of Energy's

Los Alamos National Laboratory and the University of Washington wrote.

Macken of Los Alamos said the computer model used in the

study provided a surprising finding - using a weak vaccine in many

people would be better than trying to vaccinate a smaller number of

people with a more effective dose.

" If you reduce somewhat the length of time that someone is

infective ... you end up getting a significant impact, " Macken said

in a telephone interview.

" You might be better off vaccinating twice as many people, getting a

lower level of protection, but still getting an improvement in

susceptibility. "

No flu vaccine is perfect and experts have been uncertain which

approach would work better.

Using several million doses of drugs like Roche AG's Tamiflu and

GlaxoKline's Relenza that can help prevent influenza infection

could also help, the researchers said.

The H5N1 strain of avian influenza is spreading rapidly in birds

around the world and experts believe it will soon be found

everywhere. It rarely infects people, but has sickened 190 people and

killed 107 of them, according to WHO.

If the virus mutates slightly and gains the ability to pass from

person to person easily, it is likely to become much less fatal but

could cause a pandemic.

Scientists are racing to make a vaccine against it and governments

are trying to stockpile drugs that can prevent and treat the

infection, but supplies are low.

In the meantime, health experts are trying to work out the best way

to deal with a pandemic if it comes, and want to know if schools,

businesses and transportation should be closed to try to slow the

flu's spread.

The team at Los Alamos and the University of Washington ran a complex

computer simulation of what the spread of bird flu might look like in

the United States. They say their findings would hold for any highly

mobile society.

" In the event that a pandemic influenza virus does reach the US,

according to our results, the US population could begin to experience

a nation-wide pandemic within 1 month of the earliest introductions, "

the researchers wrote.

The model assumes that about a third of the population would become

infected - the rate seen in the past two pandemics, in 1957 and 1968.

They included several circumstances for people to meet and

potentially pass the virus along, including households,

neighbourhoods, preschools, playgroups, schools, shops and work.

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