South Korean health authorities say the death of a patient which came after receiving an AstraZeneca COVID-19 vaccine is unlikely to be related to the shot, despite the presence of blood clots.

Kim Joong-gon, an official at the Korea Disease Control and Prevention Agency(KDCA), said Wednesday that there are suspicions of other causes, given the patient had underlying conditions for a long period of time.

Kim went on to cite the medical examiner’s report indicating that aspiration pneumonia could be the cause of death. Other data suggested that it could have been a myocardial infarction or an acute heart condition.

The official added that blood clots have been reported following other types of vaccinations, such as for the flu, but studies have found no connections between the events.

Kim added that a full autopsy is under way and results will come in from the police and National Forensic Service(NFS), after which further assessments will be made.