At least 23 people died in Norway after receiving the first dose of the Pfizer/BioNTech vaccine.

According to the Norwegian Medicines Agency, 13 were nursing home patients and above 85-years-old. The bodies were autopsied, with the results suggesting that common side effects may have contributed to severe reactions in frail, elderly people.

"The reports suggest that common adverse reactions to mRNA vaccines, such as fever and nausea, may have contributed to a fatal outcome in some frail patients," Chief Physician at the Norwegian Medicines Agency Sigurd Hortemo said.

The Norwegian Institute of Public Health said that it has updated the coronavirus vaccination guide with more detailed advice on vaccinating the elderly who are frail. In a statement, Pfizer said it is working with the Norwegian regulator to investigate the deaths in Norway. The agency found that 'the number of incidents so far is not alarming, and in line with expectations'.

Last month, Norway started COVID-19 vaccinations after the Pfizer/BioNTech vaccine was approved by the European Medicines Agency. According to data, more than 30,000 people in Norway have received the first shot of the Pfizer or Moderna coronavirus vaccine, Bloomberg reported.