Norway took the decision to pause using the Oxford-AstraZeneca vaccine as precautionary measure, Sara Watle, senior physician at the Norwegian Institute of Public Health said.
She told BBC World News: “The four cases were clusters so they were reported to us in a very short period of time and the four cases have all occurred in patients under 50 years of age and they all have a rare combination of symptoms with blood clots, haemorrhages and low platelet counts.”
It was “too difficult for us to conclude” whether there was a link between the blood clots and the vaccine but pausing use of the AstraZeneca jab had been “a very difficult decision”, she added.
The World Health Organization (WHO) has previously said there is no evidence of a link between clots and vaccines and urged countries not to halt vaccinations.
AstraZeneca has said there is no evidence of an increased risk of clotting due to the vaccine.