There is an increasing concern in Norway about the safety of the American company Pfizer Inc’s vaccine on elderly people with serious underlying health conditions after 29 died following inoculations.

The latest figure adds six to the number of known fatalities in Norway, and lowers the age group thought to be affected to 75 from 80.

While it’s unclear exactly when the deaths occurred, Norway has given at least one dose to about 42,000 people and focused on those considered most at risk if they contract the virus, including the elderly people.

The vaccine produced by Pfizer and BioNTech SE was the only one available in Norway, and “all deaths are thus linked to this vaccine,” the Norwegian Medicines Agency said in a written response to Bloomberg on Saturday.