An inquest next week in Samoa will further investigate the cause of death of two babies who died minutes after receiving the MMR vaccine at Safotu district hospital, the police say.
Police said samples from the post mortem of the two infants had been sent overseas for further medical analysis.
Meanwhile, the Samoa Medical Association has expressed grave concern about the deaths.
The association's president, Tanyamarie Petaia, said she believed health care providers in Samoa had an astronomical task ahead in regaining people's confidence in the safety of the health service.
The continuation of the expanded immunisation programme was of particular concern, Dr Petaia said.
The association joined all Samoan health care professionals and providers in expressing sincere apologies for inadvertently causing pain and sadness to the families of the two deceased infants, she said.