The virus targeted by the flu vaccines supplied for this season do not match the dominant virus that is circulating, reducing their efficacy, the Centers for Disease Control (CDC) said yesterday.
According to the CDC’s weekly data, 97,003 cases of flu-like illnesses were reported last week, an increase of 24 percent from the week before, indicating that the nation is experiencing the peak of this flu season.
CDC Epidemic Intelligence Center Director Liu Ting-ping (劉定萍) said that 22 people were confirmed to have serious flu complications, 18 of whom did not receive vaccinations.
“The dominant circulating virus is the influenza B virus,” she said, adding that 21 clustered cases were reported in the past four weeks, 16 of which (76 percent) were on school campuses.
The dominant circulating virus is of the Yamagata lineage, but the WHO-recommended composition of trivalent vaccines for use in the northern hemisphere’s flu season was two influenza A viruses (H1N1 and H3N2) and an influenza B virus of the Victoria lineage, CDC Deputy Director-General Chuang Jen-hsiang (莊人祥) said.
“The effectiveness of the vaccine can reach 60 to 70 percent if the predicted influenza B lineage matches the dominant circulating virus,” he said.
“Although the virus was predicted incorrectly, the vaccine can still offer cross-protection against the Yamagata lineage and has a protective efficacy of about 30 to 50 percent, which still reduces the risk of serious complications and death,” Chuang added.
Getting vaccinated still provides protection against infection and maintaining good personal hygiene by washing hands frequently, wearing a mask in crowded places and seeing a doctor when symptoms arise can also enhance protection, he said.
The CDC said the latest WHO report showed that the dominant circulating viruses are influenza A subtype H3N2 in the US and Canada, influenza A subtype H1N1 in Japan and influenza B in Taiwan, Hong Kong, South Korea, China and Europe, adding that people who are planning to travel overseas should take proper pre-emptive measures.
RSS