Jessica has reportedly undergone several surgeries, including the removal of a kidney and part of her skull, and has been in a coma.
St George's Hospital released a statement on Friday: 'On behalf of the family of Jessica Falkholt, St George Hospital has been asked to advise the media and the community that Jessica's life support has been switched off.
There has been no official confirmation from the NSW Police or hospital that the actress has died.
Lars and Vivian died instantly, and Annabelle passed away in hospital three days later.
Jessica had been in St George's Hospital in New South Wales since the devastating auto accident on Boxing Day.
Australian actor Anthony Hayes tweeted: 'Jessica Falkholt.
On Wednesday they were farewelled at a moving funeral ceremony at St Mary's Catholic Church at Concord in Sydney's west.
HOME and Away actress Jessica Falkholt's life support has reportedly been switched off, just one day after her mother, father and sister were laid to rest.
On Thursday night a woman was killed and a five-year-old boy critically injured in a crash at Milton in New South Wales.More news: Millie Bobby Brown all set to play Elona Holmes
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Both Jessica and Annabelle were pulled from the burning wreckage and taken to hospitals. Whitehall had previously received a nine-year driving ban and racked up at least 10 convictions for driving while disqualified.
Home and Away actress Jessica Falkholt's life support has been turned off after she was critically injured in a horror crash.
Paul Ponticello, Vivian's brother, gave a eulogy at the funeral.
"The irony of this tragedy is that Lars was such a careful driver".
Craig Anthony Whitall, 50, who was driving a four-wheel-drive crashed into the Falkholt's family auto.
The Falkholt family requested donations to children's charity Redkite in lieu of flowers.
Whithall - the driver of the second vehicle - is believed to have been driving on the wrong side of the road at the time of the crash. We'd always have a laugh.
He also spoke about the love between his sister and brother-in-law: "They are together and always will be". She then filmed a role in the U.S. film Harmony, which is set for release this year.