Norway launched a probe on the safety of the Pfizer Inc. vaccine, especially for the elderly people facing serious health conditions. The announcement came as 29 people died after a dose of  the Pfizer COVID-19 vaccine. About 42,000 people have been vaccinated in Norway.

Norway had only Pfizer and BioNTech SE’s vaccine until Friday. “All deaths are thus linked to this vaccine,” the Norwegian Medicines Agency responded on a query raised by Bloomberg.

“There are 13 deaths that have been assessed, and we are aware of another 16 deaths that are currently being assessed,” the agency said.

The deaths include of only “elderly people with serious basic disorders”.

“Most people have experienced the expected side effects of the vaccine, such as nausea and vomiting, fever, local reactions at the injection site, and worsening of their underlying condition,” the agency added.

The Pfizer vaccine has become a subject of criticism as the U.S. authorities reported 21 cases of severe allergic reactions from December 14 to 23. The reports came after about 1.9 million initial doses of the Pfizer vaccine.

“For those with the most severe frailty, even relatively mild vaccine side effects can have serious consequences. For those who have a very short remaining life span anyway, the benefit of the vaccine may be marginal or irrelevant,” the Norwegian Institute of Public Health said.