Vaccinating chickens against avian influenza can reduce the spread of the disease. Researchers at CIDC-Lelystad have reached this conclusion as a result of experiments they did with the H7N7 virus that caused the 2003 epidemic in the Netherlands. There is one disadvantage: it takes one to two weeks before the vaccinated chickens no longer transmit the disease.
‘It is the first time that we have shown in experiments that vaccination really prevents the spread of the flu virus,’ says Jeanet van der Goot of the Central Institute for Animal Disease Control (CIDC-Lelystad), part of Wageningen UR. The results of the research were published last week in an early internet edition of the American journal Proceedings of the National Academy of Sciences (PNAS). The research results formally only apply to the highly pathogenic strain H7N7, and therefore only give ‘an indication’ that vaccination would also help in controlling the H5N1 virus that is causing the current outbreaks of avian influenza. Van der Goot: ‘We do now know though that under ideal conditions vaccination can completely block the spread of avian influenza. But we are talking about twenty chickens, and we know their exact health status. A large-scale vaccination campaign has now started in China, but there they have about thirteen billion chickens and a number of locally produced vaccines. I wouldn’t like to say whether they will manage to bring the disease under control. To be absolutely sure you can’t miss one single chicken in the field. That sounds like mission impossible to me.’ / GvM