Taiwan: Flu vaccines not as effective this year as in the past: DOH

Flu vaccines not as effective this year as in the past: DOH

Central News Agency
2009-02-03 10:59 PM
Taipei, Feb. 3 (CNA)

Influenza vaccines that proved to be effective late last year have failed to live up to expectations early this year, the Department of Health (DOH) said Tuesday.


Chou Jih-haw, deputy director general of DOH's Centers for Disease Control, said more than 3.2 million free flu shots were given to the public in autumn and winter last year.

"Judging from the number of influenza cases in the fourth quarter of 2008, it was significantly lower than in the same period the previous year," Chou said.

"But this year, tests of flu viruses on the patients showed that the results have not been as good as expected," he continued.

Chou said influenza vaccines given in autumn 2008 and this winter should be effective against the H1N1 and H3N2 viruses, and tests taken from patients who were inoculated last year proved their effectiveness.

But in January, tests found the vaccines did not work on 70 percent of those with H1N1 viruses and 40 percent of those with the H3N2 virus.

A vaccine is considered effective if it controls the virus in 80 percent to 90 percent of those inoculated.

Chou would not categorize the vaccines as ineffective, however, because influenza viruses are "prone to mutation, " meaning that the virus formula for producing vaccines must be changed on a yearly basis.

A former CDC director suggested Tuesday that part of the problem may be that flu viruses tend to strike Taiwan between six months and two years earlier than European countries and the United States.

Su Ih-jen, director of the Division of Clinical Research of the National Health Research Institutes, said that because of the time lag, influenza vaccines produced by European and American pharmaceutical makers based on data provided by the World Health Organization could not keep up with the outbreak of flu in Asia.

Su noted that with close exchanges between Taiwan and China, Taiwan has become an outpost of influenza outbreaks.

The World Health Organization began to address the issue of different prevalent viruses in Asia and Europe last April.

Currently, two out of five major vaccine manufacturers have made inroads into China, and the production of Asian influenza vaccines "has become a trend," he said.

Su suggested that the virus in every influenza outbreak is slightly different, and that "it can show major changes about every five years, so the effectiveness of vaccines can diminish." (By Lilian Wu)
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