Robert F. Kennedy Jr.’s son, Bobby Kennedy III, posted a video of a phone call between Kennedy and former President Donald Trump in which the former president appeared to endorse false theories about the safety of vaccines.

Kennedy III posted a brief video on social media Tuesday morning filming Kennedy Jr. as he listens to Trump speak on the phone. Kennedy III said the video was taken on Sunday, the day after Trump was injured during a shooting at a campaign rally in Butler, Pennsylvania. Kennedy III deleted the post containing the video hours later.

In the video, Trump can be heard discussing the amount of doses of vaccines that are scheduled for children, and suggested that after taking a high volume of vaccines, “you see the baby all of a sudden starting to change radically.”

“When you feed a baby, Bobby, a vaccination that is, like, 38 different vaccines and it looks like it’s been for a horse. Not a, you know, 10-pound or 20-pound baby,” Trump says on the call. “And then you see the baby all of a sudden starting to change radically. I’ve seen it too many times.”

Trump also appeared to express some skepticism toward public health professionals who accurately state the recommended immunization schedule for children is safe and effective, saying, “And then you hear it doesn’t have an impact, right?”

By age 6, children may receive vaccinations that protect them from 16 different diseases, including life-threatening infections such as measles, pertussis and polio. According to the US Centers for Disease Control and Prevention, the vaccines are recommended for very young children before they are likely to come into contact with serious diseases, as they are at highest risk of serious illness or death.

Vaccines are often combined into a single dose in order to reduce the number of office visits and shots. Needles used for infant vaccines are typically an inch or less long, and for some vaccines, dose sizes for the very young are smaller than those used for older children or adults. Some infant vaccines are also administered orally, and certain flu vaccines for people as young as 2 can be administered as a nasal spray.

Kennedy Jr. apologized to Trump for the video of the phone call being released after his son took the video down.

“When President Trump called me, I was taping with an in-house videographer. I should have ordered the videographer to stop recording immediately. I am mortified that this was posted. I apologize to the president,” Kennedy wrote on social media Tuesday.

When asked whether Trump knew he was being recorded, Trump’s advisers pointed CNN to Kennedy’s tweet, in which he said a videographer was filming him for a separate project.

The Biden campaign said in a statement Tuesday, “Trump and his anti-vax bud ‘Bobby’ are spreading dangerous conspiracy theories that threaten the lifesaving care that tens of millions of people depend on.”

“This leaked footage is further proof Trump can’t be trusted to protect Americans’ health care. It’s frightening, and if he gains power, it could be the devastating reality for working families across the country,” the statement said.

CNN has reached out to the Kennedy campaign and Trump campaigns for comment.

The phone call shown in the video came one day before Trump and Kennedy met in Milwaukee. Kennedy campaign spokesperson Stefanie Spear told CNN the two presidential candidates discussed “national unity” during the meeting. A source familiar with the conversation said the two also discussed Trump’s vice presidential nomination decision hours before he selected Ohio Sen. JD Vance as his running mate.

In January 2017, before Trump was inaugurated, Kennedy said Trump had asked him to lead a commission to study vaccine safety following a meeting between the two at Trump Tower in New York. The commission ultimately never materialized.

Trump appeared to reference the meeting in the clip of the phone call.

“You and I talked about that a long time ago,” Trump tells Kennedy on the call.

Trump has long entertained vaccine skepticism, but his stance toward vaccines has taken added political urgency after Florida Gov. Ron DeSantis made his handling of the Covid-19 pandemic a major issue during the Republican primary. Trump has said he would defund any public school that enforces vaccine mandates. The policy agenda on his campaign website questions the origins of “an unexplained and alarming growth in the prevalence of chronic illnesses and health problems, especially in children.”

As a candidate, Kennedy has repeatedly made false claims about the safety and efficacy of vaccines. He’s regularly criticized Trump for approving public health restrictions during the pandemic and implementing a plan to accelerate the development of a Covid vaccine. Kennedy often attempts to link Trump to Dr. Anthony Fauci, the former director of the National Institute of Allergy and Infectious Diseases, who helped lead the US Covid response during the Trump and Biden administrations and has become a focal point of criticism from some on the right.

All vaccines that are approved or authorized for use in the United States have been proven safe and effective through rigorous scientific study. Childhood vaccinations are particularly important because they train the body’s immune system to recognize viruses it has not yet been exposed to, and protect the body from the harmful effects of those viruses.

Severe allergic reactions are exceedingly rare – occurring in roughly 1 in 1 million people. Far more common are mild side effects, such as pain or swelling at the injection site, which tend to subside quickly.

Worldwide, vaccines prevent more than 4 million deaths every year, according to the World Health Organization. And while there is still no scientific consensus on what causes autism, vaccines, conclusively, do not.

Trump also discussed with Kennedy the shooting on Saturday, which left him wounded in his right ear, and the phone call he received from President Joe Biden following the assassination attempt.

“He was very nice actually. He called and he said, ‘How did you choose to move to the right?,” Trump says in the video of his call with Biden. “I said, ‘I was just showing a chart.’ I didn’t have to tell him the chart was going all the people pouring into our country, right?”

“I just turned my head to show the chart and something raps me,” he continues. “And it sounds like a giant, like the world’s largest mosquito. And, uh, it was. It was a bullet.”

CNN’s Steve Contorno and Alayna Treene contributed to this report.