A Japanese woman in her 60s has died several days after being administered a dose of the Pfizer vaccine, the Ministry of Health, Labour, and Welfare of Japan announced on Tuesday.
The woman, said to have no underlying conditions or allergies, received the shot on 26 February.
She died on 1 March from what is presumed to be subarachnoid hemorrhage - a type of stroke affecting the space between the brain and the surrounding membrane.
The ministry will launch a probe to establish if the woman's death was related to the vaccine.
The American medication was approved in Japan on 14 February. Three days later, the country kicked off its vaccination rollout for healthcare workers
Severe side effects or fatalities ostensibly linked to the Pfizer/BioNTech vaccine have been reported in several countries. In Norway, as many as 23 elderly citizens reportedly died after receiving the vaccine.
The World Health Organisation, however, stated that it was not "aware" of any deaths linked to the vaccine.