Three Norwegian health care workers have been hospitalized after receiving the newly-unveiled single-dose AstraZeneca COVID-19 vaccine, authorities have announced, which has led to a temporary suspension of giving out the shot.

Reuters reported that the workers experienced issues relating to blood clots and other vascular issues. Norwegian authorities did not say how long the distribution of the vaccine would be halted as those people remain hospitalized.

Sigurd Hortemo with the Norwegian Medicines Agency told reporters at a media briefing with members of the Norwegian Institute of Public Health that each of the hospitalized health care workers were under the age of 50, but said the hospitalizations could not be definitively linked to the shot.