TAIPEI, Dec. 25 (Xinhua) -- Taiwan has reported an earlier outbreak of flu this winter with more than 100,000 people going to hospital for treatment last week.

The number of recorded flu cases from Dec. 15 to 21 increased by 7.6 percent from the previous week, the health department said, adding that this winter's flu outbreak started earlier than the previous two years.

The current flu cases in Taiwan were mainly caused by influenza A/H1N1 virus, which more easily affects middle-aged adults.

From January to Dec. 21, Taiwan recorded a total of 2,158 serious flu cases, the highest over the past five years.