HONG KONG - The re-emergence of bird flu in Asia and Egypt was partly because poultry farms were not using the right vaccines and that the virus is mutating, experts said on Tuesday.
Guan Yi, of the University of Hong Kong and an expert on H5N1 virus, warned that poultry farms in some parts of the world were using vaccines that did not provide full protection against the H5N1 and can't keep up with its mutation process.
"The vaccine (used in Hong Kong) was made to fight an American strain of the H5N2, and it is very different from the Guangdong strain of the H5N1 virus here," he said.
"When there were no outbreaks, we just assumed it was protective. Now that there is an outbreak (on a Hong Kong farm), we assume it is useless," he said.
Since late November, the virus has infected two children in Indonesia, killing one of them. Earlier this week, it killed a 16-year-old girl in Egypt, too. And a youth in Cambodia tested positive for the virus after eating chicken.
"The virus is definitely mutating," Guan said, warning that authorities in some areas were using batches of vaccine that may no longer be effective.
Since 1997, when H5N1 was identified in Hong Kong, scientists have discovered 10 strains of the virus, which shows the speed and extent at which it is mutating, though it has not mutated to pass from human to human.
The strain found in Indonesia, for example, is very different from the H5N1 strain in Europe, the Middle East and Africa.
"There is a theoretical possibility that the strain being used in the vaccine is too different from the one circulating," said Albert Osterhaus, a leading virologist with Erasmus Medical Center in Rotterdam, the Netherlands.
China Daily - Agencies