AZ vaccine more effective with 8-week interval between doses: Chen

TAIPEI (The China Post) — Health Minister Chen Shih-chung (陳時中) confirmed on Tuesday that delaying the second shot of the AstraZeneca (AZ) vaccine to eight weeks may boost its efficacy against COVID-19.

Speaking during a press conference, Chen said that the Food and Drug Administration (食藥署) first announced on Feb. 20 that the interval between two doses of vaccine would be between 4 to 12 weeks.

Such interval was later revised to 8 weeks.

Chen explained that the revision was made yesterday based on the latest research results released by AZ which indicated that the protection of the first dose would be at 76 percent when administered.

The report went on to say if the second dose was extended to 12 weeks, the protection could be increased to 82.4 percent.

Chen said that although it was not a large-scale study, it is only a new study focusing on the interval of vaccination and its subsequent effect.

The World Health Organization (WHO, 世界衛生組織) recommended on Feb. 10 to administer the two doses 8 to 12 weeks apart, though the subsequent vaccination time will be revised and reviewed on a regular basis according to new scientific evidence and data post-market.