A total of 47 cases of anaphylaxis, a severe and potentially fatal allergic reaction, have been reported after some 580,000 shots of Pfizer Inc.'s COVID-19 vaccine were administered to health workers in Japan, the health ministry said Friday.
All recovered after receiving treatment, according to the ministry, with its panel of experts concluding that there are no serious concerns about the safety of the vaccine at this time.
The figure as of last Sunday implies an anaphylactic reaction rate of around 81 cases per million doses administered, much higher than five cases in every 1 million doses administered in the United States and 20 cases per million in Britain.
However, Japan is further behind in its vaccine rollout, and the rate could change as more people receive shots.
"Due to various differences such as inoculation targets, it cannot be simply compared with the frequency overseas," a ministry official said.
Japan is in the process of inoculating some 4.8 million health care workers nationwide before expanding to people aged 65 or older in mid-April. People with pre-existing conditions, such as diabetes, and those working at elderly care facilities are slated to come next.