The two latest deaths were reported to the Swedish Medical Products Agency (Läkemedelsverket) on Friday.
A 74-year-old woman from Sollefteå in northern Sweden died four days after receiving the swine flu vaccine.
The woman, who suffered from heart and lung disease, was classified as a high-risk patient.
“Naturally a report will be undertaken,” said Dr. Markus Kallionen in a press statement released by Västernorrland County Council.
“We must take this case seriously and investigate what has happened.”
A further case of a 90-year-old woman who also died after receiving the vaccine has been reported by newspaper Expressen.
Läkemedelsverket are currently investigating circumstances surrounding the deaths of two high-risk patients, a 50-year-old man with a serious heart condition and woman with an acute muscle disease.
“It’s important to says that they had complicated illnesses,“ Gunilla Sjölin Forslund from Läkemedelsverket told news agency TT.
“We still do not know if the deaths are connected to the vaccine.”
Sweden launched a mass vaccination programme in a bid to control the flu pandemic on October 12th.
Cases of swine flu reached record levels last week with 198 new cases in comparison to 93 the previous week.