Finland has suspended the use of AstraZeneca's coronavirus vaccine as a precautionary measure after recording two cases of unusual blood clotting in the brain.
Health officials announced at a press conference on Friday that the suspension would last at least a week, but stressed it was a precautionary measure.
Officials said the cases that caused concern could be unrelated to the vaccine although they did occur between four and ten days after the shot was administered.
Similar instances have been recorded in other European countries, but so far not in numbers greater than would be expected in the general population.
Hanna Nohynek from THL said that women aged 20-50 have been worse affected by the clotting events, but any possible connection with the vaccine was not yet understood.
People who have received the AstraZeneca vaccine were urged to seek medical help if they had an unusual symptom.
"Those who have an appointment to be vaccinated should wait to be contacted by the vaccinating organisation about any possible cancellation," said THL in a statement on its website. "Vaccination appointments can also be cancelled by the patient themselves."
"Those who have received the AstraZeneca jab are urged to watch out for unusual symptoms, which could begin more than three days after vaccination. It's important to seek care immediately if you get a powerful headache that continues to worsen, or serious bruising on the skin or in the mouth."
The suspension will last for at least one week, with 29 March the earliest date AstraZeneca vaccinations could resume.
Several other countries have temporarily suspended use of the AstraZeneca vaccine, but the European Medicines Agency said on Thursday that it saw no link between blood clotting events and the vaccine.
After that announcement several countries resumed inoculation with the AstraZeneca shot.
This story is being updated