Norway on Saturday expressed concern about the safety of Pfizer’s coronavirus vaccine on elderly people with serious underlying medical conditions, after at least 29 of them died within days of receiving the shot, Bloomberg reported.

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

“There are 13 deaths that have been assessed, and we are aware of another 16 deaths that are currently being assessed,” the agency added. All the reported deaths relate to “elderly people with serious basic disorders”.

Norway said that most of the people 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”.

On Friday, Norwegian Medicines Agency Chief Physician Sigurd Hortemo had said that common reactions to the vaccine, including fever and nausea, “may have contributed to a fatal outcome in some frail patients”.

The findings prompted the Scandinavian country to suggest that the Pfizer vaccine may be too risky for elderly vulnerable patients. “For those with the most severe frailty, even relatively mild vaccine side effects can have serious consequences,” the country said. “For those who have a very short remaining life span anyway, the benefit of the vaccine may be marginal or irrelevant.”

At the same time, Norway’s health agency said the deaths were an expected outcome of the process.

“The Norwegian Medicines Agency has communicated, prior to the vaccination, that when vaccinating the oldest and sickest, it is expected that deaths will occur in a time-related context with vaccination,” it said. “This does not mean that there is a causal link between vaccination and death. We have also, in connection with the reported deaths, conveyed that it is possible that common and known side effects of the vaccines may have been a contributing factor to a serious course or fatal outcome.”

The country, however, adjusted its advisory on who gets the Covid-19 vaccine, leaving it up to each doctor to consider who should be vaccinated, AP reported. “Doctors must now carefully consider who should be vaccinated,” said Steinar Madsen, medical director with Norway’s medical agency. “Those who are very frail and at the very end of life can be vaccinated after an individual assessment.”

Pfizer said it was working with the Norwegian regulator to investigate the deaths in the country, Bloomberg reported.