Washington DC - Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. has walked back on his promise to release a report on the causes of autism by September.

In a recent interview with CNN, Kennedy – a well-known anti-vaccine advocate – revealed that the public can now expect the results to come out in March of next year.

"The most solid information, it will probably take us another six months," Kennedy said.

"We're going to begin to have a lot of information by September," he continued. "We're not going to stop the studies in September. We're going to be definitive. The more definitive you are, the more it drives public policy."

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Last month, Kennedy announced the "massive testing and research effort" that would involve "hundreds of scientists from around the world."

He vowed then that "By September, we will know what has caused the autism epidemic, and we'll be able to eliminate those exposures."

The delay announcement came the same day that Kennedy's Make America Healthy Again Commission released a report that outlined contributions to chronic childhood illness, including the long-debunked claim that childhood diseases are linked to vaccines.

During a press conference for the report, President Donald Trump further pushed Kennedy's claims, stating the rise in autism rates in recent years "has to be artificially induced."