An Idaho mother charged with the first-degree murders of her 18-month-old twins has blamed their deaths on vaccines they received eight days before they died. But doctors who reviewed details about the case at the request of the Guardian say vaccines did not kill them.

“This was not a close call,” said Dr Jake Scott, a clinical infectious disease physician at Stanford who specializes in vaccine science. “I can say with confidence what didn’t happen here. It was not the vaccines.”

Andrea Shaw was indicted for murder last month in the deaths of Dallas and Tyson, who were found dead in their bed in Payette, Idaho, on 1 May 2025.

Three days after the twins died, Shaw and her husband, Nathaniel, did a video interview with Children’s Health Defense (CHD), the anti-vaccine group that Robert F Kennedy Jr ran for years before becoming the secretary of the US Department of Health and Human Services. At the time, no autopsy results had been released and no cause of death was publicly known.

Despite that lack of information, CHD’s Polly Tommey repeatedly blamed vaccines during the interview. Since then, CHD has cited the children’s deaths to promote the idea that vaccines are dangerous. An article it published about the deaths was a top story on its website last year, according to its 2025 Impact Report, and it added Shaw as the lead plaintiff in a lawsuit the group filed against the American Academy of Pediatrics.

CHD has continued to stand by Shaw since her 30 June arrest.

Three doctors who reviewed information about the case said it wasn’t possible the children died because of a reaction to any of the three vaccines they received. They based their conclusions on several factors, including the kinds of vaccines they received, the timing of the children’s deaths and descriptions of their condition in partial emergency room visit reports obtained by the Guardian. They also took into account Shaw’s description of her children’s symptoms and the cause of death being determined to be suffocation.

“There’s no biological plausibility to a vaccine suffocating somebody,” said Dr Amesh Adalja, an infectious disease physician and senior scholar at the Johns Hopkins Center for Health Security.

Scott said if the children were having a deadly reaction to any of the three vaccines they received, it would have been apparent within minutes or hours, not eight days later.

“These three vaccines are all non-live vaccines. The only established way that any of them causes a death is a severe allergic reaction,” he said. “I’ve spent a lot of time reviewing vaccine safety data, and I’m quite certain about this.”

He said such a reaction would “absolutely never” kill someone eight days later.

The timeline

The children each received three vaccines on 23 April 2025: DTaP (diphtheria, tetanus and pertussis), hepatitis A and influenza. Shaw’s mother-in-law was with Shaw and the children at the appointment and said in a court filing that she told the nurse she and her son had adverse reactions to the flu shot, but the nurse assured them it should not be a concern. Shaw agreed to the children being vaccinated.

The following day, Shaw took the twins to the emergency room because she said they had “severe symptoms including blue lips, lethargy, and sunken eyes”, according to her lawsuit against the American Academy of Pediatrics. But partial records from those visits shared with the Guardian by CHD do not indicate the children were severely ill, Scott said.

The records of both note a possible vaccine reaction, but describe mild symptoms, not something serious, Scott said.

“Feeling warm, being fussy, having less energy or less appetite for a day or two after shots – it’s one of the most common and expected reactions there is, especially at this age,” he said.

Dallas had a temperature of 99, and the records said she had a decreased activity level, while Tyson was described as “very active”. Both had good eye contact and were taking fluids orally, according to the records.

Adalja said the records described a “very benign presentation”.

The children were sent home without further tests.

Shaw has said the twins continued to do poorly, but on 30 April, one week after the trip to the ER, she told CHD the twins had improved.

“They were great. That was the only day since those shots that they were active,” Shaw said in her video interview last year. “They were eating fine. They were drinking out of their sippy cups fine. They were talking normally finally. And they didn’t want to sleep all day.”

The following morning, she said, she found the twins dead in the bed they shared.

Scott said that from a purely scientific perspective, the explanation that vaccines were to blame doesn’t hold up.

“There is no vaccine injury that improves and then kills a child overnight,” Scott said. “And certainly not two children in the same night.”

Much anti-vaccine messaging focuses on mercury and the preservative thimerosal, but thimerosal was removed from childhood vaccines in the US more than two decades ago, though it is still in some multi-dose flu vaccines. A chart that detailed Dallas Shaw’s visit to get the vaccines, and which appeared on a CHD video last year, shows that the influenza vaccine she received was the single-dose, preservative-free formulation, Scott said.

And while most flu vaccines are grown in hen’s eggs, prompting concerns for some people with egg allergies, the vaccine that was recorded in the chart was not made that way.

“It contains no egg protein at all,” Scott said.

The case against Shaw

Shaw’s lawyer, Joseph Filicetti, said he doesn’t have to prove beyond a reasonable doubt that the vaccines were the cause of the twins’ deaths.

“I’m focused on a criminal case with my client. And it appears to me that vaccines” played “a role in this,” he said. “There’s enough complications going on and it looks pretty obvious to me that vaccines are in play.”

He questioned whether the doctors the Guardian consulted would be able to make their determinations about vaccines without having full access to the Shaw twins’ medical records.

“I don’t know how a doctor could give an opinion without seeing the entire medical record,” Filicetti said.

The conclusions by doctors interviewed by the Guardian align with those of three doctors consulted by prosecutors, who said in a filing this week that they ruled out other possible causes of death including excessive heat, carbon monoxide poisoning and other kinds of poisoning.

“The Defendant described them as having a great day the day prior to their murders. Detectives, with the benefit of three medical doctors, were able to rule out vaccines as a cause of death,” prosecutor Michael Duke wrote.

Duke told a judge during a bond hearing this week that Shaw changed her story “radically”, initially saying she fed the children breakfast and went through their routine, before backtracking and acknowledging that wasn’t true.

Duke said Shaw told investigators she saw one of the children sit up between 1am and 2am when she checked on them upon returning home from going out with a friend. Then, he said, she “changed her story again to say that she didn’t actually see the kid sit up after being emphatic that he had”. He said the children are thought to have died around that time.

“The reality is this is not a vaccine case,” Duke told the judge, adding: “This is a case where a mother, unfortunately, has killed her two children.”

The judge on Tuesday revoked Shaw’s $2m bond, agreeing with the prosecutor’s argument that she posed a threat to her new baby, who was born last month, just days before her arrest.

The role of Children’s Health Defense

Scott was highly critical of CHD and its use of the case to further its anti-vaccine cause.

CHD didn’t wait for the evidence but “built the story first and ignored the record that totally contradicted it”, Scott said.

Asked why CHD jumped to the conclusion that vaccines were to blame before a cause of death was determined, the organization’s CEO, Mary Holland, said in an email that the twins’ deaths follow “a typical pattern of an adverse reaction to pediatric vaccines”. Though Shaw has been charged with two counts of murder and medical experts consulted by prosecutors ruled out vaccines, Holland said CHD is not re-examining its support of Shaw.

“Everyone in this country is presumed innocent until it is proven beyond a reasonable doubt that they are guilty. We see no reason to believe otherwise about Ms Shaw,” Holland wrote in an email.

Scott said he didn’t know how the twins died, but he does know it wasn’t the vaccines.

“This is what the movement does: it finds a tragedy, attaches a vaccine to it” and uses the grief to garner support, he said. “An organization that cared about these children I think would have waited to find out how they died.”