A mother whose baby died in Samoa after getting the measles, mumps and rubella (MMR) vaccine says she wants answers about what went so terribly wrong.
Marietta Tuisuesue's one-year-old daughter died on Friday after visiting a hospital on the island of Savai'i to get the injection. On the same day, a one-year-old boy died after also getting an MMR shot.
Ms Tuisuesue says she noticed the condition of her daughter deteriorated rapidly after the vaccine was administered.
She told TV1 Samoa: "Her body was turning black, so I ran back up to the doctor. She was still breathing at the time. We went into the consultation room and I came out while they worked on her. Not long after that, they came out and told me that my daughter had passed away."
The Director General of Health in Samoa, Dr Take Naseri, says all vials of the vaccine have been seized and the nationwide vaccination programme has been suspended while an investigation is carried out.
"We are very serious in looking at the cause and looking at why it happened and to prevent this from happening ever again," he told Newshub.
Samoa has been using MMR vaccines for more than a decade without issues. Experts in New Zealand say the incident in Samoa should not put parents off getting their children protected.
Dr Helen Petousis-Harris, the director of vaccinology research at University of Auckland, says millions of children have safely been vaccinated using the MMR vaccine and she's confident it's safe.
"I think we need to keep in mind that this vaccine and similar vaccines have been administered to almost every child in the world. They're incredibly safe."
When injected, the vaccine powder must be mixed with diluent - normally a sterile, water-based solution.
There have been a handful of cases where deaths have occurred overseas. But those incidents were because the diluent was mixed up with another drug or because the vaccine had become contaminated due to poor storage. In 2014, 15 children died in Syria after muscle relaxant was mistakenly mixed with the measles vaccine. Last year in South Sudan, 15 children died after the same needle was used repeatedly and the vaccine hadn't been refrigerated.
Dr Petousis says while it's too soon to know what has occurred, it "seems likely" that in the case of the tragedies in Samoa the vaccine had not been administered correctly.
The nurses who gave the vaccines have been stood down but told officials they followed proper procedure.
Samoa's Prime Minister says an inquiry "will determine if negligence was a factor". A specialist forensic expert will undertake an autopsy on the bodies of both babies to help understand what's occurred.