Bird-flu vaccinations work, but countries weigh costs

By Kay Johnson and Peter Janssen Feb 23, 2006, 13:59 GMT

Hanoi/Bangkok - As France and the Netherlands move ahead with plans for bird-flu vaccinations, two Southeast Asian countries offer different lessons for Europe about how best to keep the deadly H5N1 virus from taking hold in the human population.

In Vietnam, the country hardest hit by bird flu in the world, an aggressive vaccination programme involving 241 million chickens and ducks appears to have had dramatic results with no new outbreaks in poultry for one month and no human deaths since November.

Thailand, on the other hand, has also brought bird flu under control for the time being but without vaccinations - because to do so would further damage the country's once-robust frozen-chicken exports.

If there is any lesson that Europe can learn from Asia's three-year fight against bird flu, it is to take the battle to where H5N1 poses the biggest threat - in domestic poultry - and hopefully deny the virus the contact with humans it would need to mutate into a pandemic human flu strain.

'There's not a magic bullet - one intervention that will wipe out the virus,' said Hans Troedsson, country director for the World Health Organization in Vietnam and also acting representative for the UN Food and Agriculture Organization.

'We have to remember that for the moment, this is an epidemic among poultry,' Troedsson said. 'From a human public-health perspective, as the virus is now, it's, of course, not a huge problem.'

Poultry vaccinations can both protect flocks from infection by around 80 per cent and also reduce the risk of the H5N1 strain of bird flu from acquiring the ability to become infectious among humans. They have such protective qualities because avian-flu strains usually mutate by 'recombining,' or switching genetic material with existing flu strains in people who are exposed to bird flu while already infected with human flu.

European countries have less immediate risk of seeing human cases than Asia or Africa because, unlike many Asian countries, there are fewer live-chicken markets, fewer backyard poultry and fewer people slaughtering their own meat at home, Troedsson added.

Since humans now only catch H5N1 from the blood, saliva or faeces of infected birds, European poultry poses a lower risk to humans.

'The advantage for the European countries is that their surveillance is already there,' said Caroline Benigno, an avian-influenza expert at the Bangkok office of the UN Food and Agriculture Organization. 'In fact, we use their experts to train people here in Asia. And the awareness is there also.'

The greatest risk to Europe is still not to people but to its poultry industries, which could suffer great financial losses if H5N1 becomes endemic.

That's what happened in Thailand, which exported almost 400,000 tons of frozen chicken in 2003 before bird flu was detected. Once news of bird flu hit, though, exports were down to less than 20,000 tons in 2004 because of import bans by the European Union and most other former markets.

Thailand resisted poultry vaccinations, though, despite losing 29 million birds, or 14.5 per cent of its poultry population, because under World Organization of Animal Health regulations, there is a 12-month wait for countries that opt for vaccinations to resume exports.

If, as Thailand did, a country opts for culling - the mass slaughter of poultry in infected areas - it may resume exports of uncooked chicken meat within six months of declaring itself bird-flu-free.

The European Union has now allowed imports of 'cooked chicken' meat from Thailand, raising such imports from 170,000 tons in 2003 to 280,000 tons last year.

Vietnam's poultry industry also suffered, costing its small poultry farmers about 300 million dollars in lost income.

But because Vietnam's poultry industry is mostly for domestic consumption, not export, vaccinations did not face opposition from large poultry exporters, Troedsson said.

Plus, bird flu is already endemic in Vietnamese poultry, and mass cullings have not worked. Vietnam had culled about 100 million domestic chickens and ducks, but by this time last year, the H5N1 virus was so widespread in Vietnam that nearly every province was reporting outbreaks. <!--page-->

So in September, Vietnam launched a massive nationwide vaccination campaign and combined it with public education, a ban on live poultry markets in cities and inspection of meat. So far, the campaign has had success, and although Vietnam reported dozens of new human cases in the winter months of last year, there have been none so far in 2006.

Like Thailand and Vietnam, countries around the world need to tailor their bird-flu response to their own needs and also educate the public on how bird flu does and does not spread to people to avoid hysteria.

'What other countries could definitely learn from Vietnam is that there is a need to take quite drastic preventative measures,' Troedsson said. 'If you go with vaccination, you need to go for a large scale as they did in Vietnam. If you go for culling, you need to go for an efficient culling early.'

'The less the H5N1 virus is circulating in the environment, the less it is in the poultry population and the less chance there is that this virus strain will mutate and cause a pandemic,' he said.