International
Despite concern that the composition of vaccines used by the city for the coming flu season differs from the latest recommendation by the World Health Organisation, Hong Kong's authorities and top medical experts said on Tuesday that vaccination would still be useful in preventing the disease.
The global health watchdog announced last Thursday that the vaccine strain against influenza A H3N2 for the southern hemisphere next year had been changed to the Singapore strain, different from the Hong Kong strain found in the city's 460,000 doses of flu vaccines, which will be given out under the government's vaccination programme beginning this month.
The composition of the city's vaccines was based on the WHO's recommendations for the northern hemisphere, announced in February.
But the latest suggestion cites studies that show recent H3N2 viruses, which were predominant globally from February to September this year, had been "better inhibited" by antibodies produced against the Singapore strain, compared to other virus strains.
The city's Centre for Health Protection said, however, that "no significant antigenic changes in the current predominating H3 strain" had been detected.
"[The Hong Kong strain and the Singapore strain] are antigenically similar, with no antigenic drift," a centre spokesman said.
Antigenic drift refers to small changes in the genetic code of a virus that take place over time as a result of mutations. It can result in a new strain of virus against which the original antibodies are less effective.
The centre said the WHO made different recommendations on flu vaccines for the northern and southern hemispheres. But apart from the winter flu season in 2014/2015, no antigenic drift had been detected.
It added that vaccines would provide a certain degree of protection for "different but related strains" and would reduce the severity of diseases for high-risk groups.
Professor Yuen Kwok-yung, a top microbiologist from the University of Hong Kong, agreed that vaccines would be useful for vulnerable groups despite "uncertain"protection against the H3N2 virus.
"Panic is always unnecessary. The coming season flu vaccine should at least protect against H1N1 and influenza B viruses if they do not drift, but the degree of protection for H3N2 is uncertain," Yuen said.
He said that antiviral drug Tamiflu could always be considered for high-risk groups, such as residents in elderly homes and hospital patients, if the winter flu surge was severe.
Dr Ho Pak-leung, another HKU microbiologist, said mismatches between vaccines and the actual predominant virus had happened regularly in the past decades, as production of vaccines was based on the WHO's predictions.
He said he expected the chances of a H3N2 outbreak to be smaller after an unusually high number of cases in the summer.
Health minister Professor Sophia Chan Siu-chee said it was "too early" to conclude whether to deem the vaccines effective, as both the flu season and the vaccinations had not yet begun.
She said the centre's scientific committee would monitor
The global health watchdog announced last Thursday that the vaccine strain against influenza A H3N2 for the southern hemisphere next year had been changed to the Singapore strain, different from the Hong Kong strain found in the city's 460,000 doses of flu vaccines, which will be given out under the government's vaccination programme beginning this month.
The composition of the city's vaccines was based on the WHO's recommendations for the northern hemisphere, announced in February.
But the latest suggestion cites studies that show recent H3N2 viruses, which were predominant globally from February to September this year, had been "better inhibited" by antibodies produced against the Singapore strain, compared to other virus strains.
The city's Centre for Health Protection said, however, that "no significant antigenic changes in the current predominating H3 strain" had been detected.
"[The Hong Kong strain and the Singapore strain] are antigenically similar, with no antigenic drift," a centre spokesman said.
Antigenic drift refers to small changes in the genetic code of a virus that take place over time as a result of mutations. It can result in a new strain of virus against which the original antibodies are less effective.
The centre said the WHO made different recommendations on flu vaccines for the northern and southern hemispheres. But apart from the winter flu season in 2014/2015, no antigenic drift had been detected.
It added that vaccines would provide a certain degree of protection for "different but related strains" and would reduce the severity of diseases for high-risk groups.
Professor Yuen Kwok-yung, a top microbiologist from the University of Hong Kong, agreed that vaccines would be useful for vulnerable groups despite "uncertain"protection against the H3N2 virus.
"Panic is always unnecessary. The coming season flu vaccine should at least protect against H1N1 and influenza B viruses if they do not drift, but the degree of protection for H3N2 is uncertain," Yuen said.
He said that antiviral drug Tamiflu could always be considered for high-risk groups, such as residents in elderly homes and hospital patients, if the winter flu surge was severe.
Dr Ho Pak-leung, another HKU microbiologist, said mismatches between vaccines and the actual predominant virus had happened regularly in the past decades, as production of vaccines was based on the WHO's predictions.
He said he expected the chances of a H3N2 outbreak to be smaller after an unusually high number of cases in the summer.
Health minister Professor Sophia Chan Siu-chee said it was "too early" to conclude whether to deem the vaccines effective, as both the flu season and the vaccinations had not yet begun.
She said the centre's scientific committee would monitor
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