McCarthy is officially named a cohost. Watch Barbara Walters make the big announcement.

NEW YORK — Less than a week after Elisabeth Hasselbeck said her goodbyes after 10 years on "The View," another divisive blond has joined the daytime talk show.

On Monday, Barbara Walters confirmed the rumors that Playboy model-turned-anti-vaccine-crusader Jenny McCarthy would officially become a co-host on "The View" when it launches its 17th season on Sept. 9.

"We love her because she's fun and uninhibited and opinionated enough to help us begin the latest chapter in 'The View' history," Walters said on the air of McCarthy, who has made 17 appearances on the show, including eight as a guest co-host.

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"Uninhibited" and "opinionated" are certainly two ways of describing McCarthy, but her detractors are more likely to use harsher language.

Though she launched her own little-watched talk show on VH1 in February, McCarthy has remained in the spotlight — and come under fire — in recent years thanks mostly to her support for the discredited theory that childhood vaccinations cause autism.

It's a stance that could prove more controversial than anything the conservative Hasselbeck or her liberal colleague Joy Behar ever said on "The View."

Watched by some 3 million viewers a day — most of them women, many of them mothers — the show is known for spirited conversations about hot-button issues, and there are few topics as heated as the vaccine debate. Though it's unlikely the subject will come up every day, or even very often, the mere fact that McCarthy is being given a national platform is enough to worry some of her critics.

"I think a network hiring a homicidal maniac, giving her a forum in front of people who have young children and are impressionable, is the most irresponsible thing I've heard of in a long time," said Michael Specter, a New Yorker magazine staff writer and author of the book, "Denialism: How Irrational Thinking Hinders Scientific Progress, Harms the Planet, and Threatens Our Lives."

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McCarthy wasn't always so polarizing. A 1994 Playmate of the Year, she rose to fame as co-host of the MTV dating show "Singled Out," where her raunchy sense of humor and buxom blond looks made her popular with men and women alike.

After leaving that program, she dabbled in TV and film roles until 2005, when her son, Evan, was diagnosed with autism. A self-styled "mother warrior," McCarthy has since written several books about the disorder and remains perhaps the best-known celebrity advocate of the theory tying autism to vaccinations.

She is president of Generation Rescue, a nonprofit group that supports this view, and has also publicly defended Andrew Wakefield, the former doctor who authored the 1998 journal article suggesting a link between the measles-mumps-rubella (MMR) vaccine and autism. The paper, largely responsible for sparking present-day fears over vaccinations, has since been retracted, and Wakefield barred from practicing medicine in the United Kingdom.

McCarthy's association with the anti-vaccine movement is so strong that there is even a website, "The Anti-Vaccine Body Count" (originally titled "The Jenny McCarthy Body Count") charting the number of deaths due to preventable diseases since 2007, when McCarthy first began to speak out on the subject.

"McCarthy has been a leading and very prominent proponent of the concept that vaccines are somehow causally related to the development of autism in children," said Dr. William Schaffner, chair of the department of preventive medicine at Vanderbilt University. "From the point of view of the scientific and the public health community and clinical family doctors and pediatricians, that concept simply is false."

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While a willingness to say outlandish things is virtually a prerequisite for co-hosts on "The View," McCarthy's position on the vaccine issue has already made her hiring the subject of fierce criticism.

Last week, as reports surfaced that McCarthy was in talks with ABC, Slate science writer Phil Plait encouraged readers to contact the network and urge executives not to hire her. A similar letter-writing campaign was initiated by Every Child By Two, a nonprofit founded by former first lady Rosalynn Carter to raise awareness about childhood vaccines.

McCarthy may be that rare person who can unite forces on both sides of the political spectrum: Last week, both the left-leaning website Salon and the conservative magazine Commentary ran pieces characterizing her as a public health threat.

While their pleas seem to have fallen on deaf ears at the Disney-owned network, the online backlash against McCarthy was swift and furious Monday.

"Congrats ABC for hiring vaccine crank Jenny McCarthy for her 'outrageous... fresh POV,' [because] actual medical science is so stale and dull," tweeted Time magazine's television critic, James Poniewozik, who also wrote a column denouncing the decision.

A spokesperson for ABC declined to address the controversy, saying only, "We are celebrating the announcement of her joining the show. That is our focus today."

McCarthy's personal publicist did not respond to a request for comment, nor did representatives of Generation Rescue.

Her detractors, however, were less reserved.

"She's very dangerous. It's unfortunate that in our society, scientific evidence is now just taken as some other point of view," said Specter, adding that recent outbreaks of easily preventable diseases such as measles are "directly attributable" to people like McCarthy.

Amy Pisani, executive director of Every Child by Two, said she felt "deflated" by the news.

"Any time she provides her opinion, it results in people listening," she said. "I feel that we don't have any more children to spare."

While it remains to be seen whether McCarthy will use "The View" as a bully pulpit for her opinions, the new job will bring her greater visibility and influence, even if she never so much as utters the word "thimerosal" on the air.

If nothing else, say her critics, perhaps McCarthy will be forced to defend — or even recant — her beliefs on "The View."

"I would hope that her colleagues on the show, if the subject comes up, will take issue with the erroneous information," Schaffner said. "These erroneous concepts must be rebutted and they have to be rebutted immediately."

Specter, however, failed to see a silver lining: "ABC should fire her."

meredith.blake@latimes.com