Japan launches study to verify COVID vaccines’ effects on citizens

The study, targeting around 1,500 people, aims to assess the effect of U.S. pharmaceutical company Pfizer Inc.'s vaccine on Japanese people after the government approved its use based on data from clinical trials conducted by the company abroad.

In Pfizer's clinical trials, which targeted around 40,000 people in the United States and other locations, the vaccine achieved 95 percent efficacy in preventing the coronavirus. But the efficacy rate fell to 74 percent among Asians, although their participation was small in the trials.

A separate trial conducted in Japan showed results signaling the vaccine's efficacy, but there was insufficient data as the trial only had 160 participants.

In the government's efficacy test, a health ministry research group separates the 1,500 participants into two groups -- those who are vaccinated and those who are not -- and then observes them for six months to determine the number of people who become infected and which ones develop coronavirus symptoms, as well as the amount of antibodies in their blood, the sources said.

The participants have been solicited from people, including medical staff at the Osaka City University Hospital and workers at the Osaka municipal government.

The Ministry of Health, Labor and Welfare also plans to conduct similar studies on the effectiveness of vaccines developed by U.S. pharmaceutical and biotechnology company Moderna Inc. and Britain's AstraZeneca Plc, which were approved by the government in May.