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Concerns are rising in Hong Kong that the umbrella H5N2 vaccine currently used to protect poultry may be losing its effectiveness after authorities discovered birds, reportedly vaccinated, that appeared to have died from the H5 virus.
Testing is underway to determine the exact strain of H5 virus responsible, and we should know more in the next day or two.
For now, aggressive culling is ongoing, with up to 90,000 birds expected to be destroyed by week's end. The government has announced a a 21-day shutdown of the local poultry industry, and is temporarily suspending all live chicken imports from mainland China.
Hong Kong, which saw the first known outbreak of human H5N1 in 1997, has a reputation for swift action when facing the virus. Their decision to cull all of the poultry in the territory may have prevented a pandemic more than a decade ago.
As it was, the H5 virus basically went into hiding until it resurfaced again in 2003 - again in Hong Kong - when two people became infected (one died) after recent travel to China's Fujian Province. A third family member died in mainland China, but was not tested.
By the end of 2003, the H5N1 virus would have shown up in Korea, China, and Thailand as well.
The H5N2 vaccine from the Netherlands has worked well protecting poultry in Hong Kong over the past six year, but recent testing at the University of Hong Kong has revealed a substantial decrease in antibody response to the vaccine over the past eight years.
Microbiologist Yuen Kwok-yung recently warned that the vaccine may be approaching total failure.
This announcement from News.gov.hk
H5N1 vaccine to be studied
Hong Kong has asked Mainland authorities to do a joint study to see if the H5N1 vaccine is more effective than the H5N2 vaccine currently used in the city, Secretary for Food & Health Dr York Chow says. It will also work with the University of Hong Kong to see if it is better way of vaccination.
Speaking to reporters today Dr Chow said the Government will inspect the Yuen Long farm affected recently by a bird flu outbreak to see whether it lacks biosecurity, and will also study if there is a change of immunity of its chickens.
"We have been using the H5N2 vaccines manufactured in the Netherlands. Over the last few years it has been proven to be effective, but we also think because of the change of the virus, we might have to look for a more appropriate vaccine," he said.
"The Mainland has introduced an H5N1 vaccine in the last few years. They have also modified it every now and then. So we have explored this option to look at whether we should change to the H5N1 vaccine too. But it is too pre-mature to decide on that."
