The results of further viral tests on a two-year-old boy who was infected by avian flu in Guangdong have health experts worried as there is no vaccination so far to stop the particular strain from circulating among poultry.
The boy, who came to Hong Kong from Guangdong, was confirmed to have caught bird flu last week. He remains in serious condition in the paediatric intensive care unit at Princess Margaret Hospital.
Further viral tests yesterday confirmed that the H5 gene of the virus sample taken from the boy belonged to the 2.3.2.1 clade, the Centre for Health Protection (CHP) said.
Dr Lo Wing-lok, a microbiologist, said this was a relatively new strain discovered on the mainland two years ago.
'The mainland is very worried about 2.3.2.1 ... The vaccination now used on poultry is not wholly effective against this type,' he said.
Lo said the current vaccine could suppress flu symptoms on birds so that even infected birds appeared healthy. 'But the virus is still circulating among the 'healthy' poultry,' he said.