U.S. congresswoman Gabrielle Giffords has been moved to a Houston rehab centre where her husband hopes the "fighter" continues on the path to a full recovery after she was shot last week outside a grocery store in Tucson, Ariz.

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People wave and applaud as the ambulance carrying Congresswoman Gabrielle Giffords leaves University Medical Center in Tucson, Ariz., on Friday. Giffords was being transported to a medical facility in Houston. ((Matt York/Associated Press))

On Friday, an ambulance — escorted by a group of motorcycle riders from a Veterans of Foreign Wars post who know Giffords — left Tucson's University Medical Center for Davis-Monthan Air Force Base, from which Giffords was flown to a Houston airport. She was then taken by helicopter to TIRR Memorial Hermann hospital, a 119-bed facility that is part of the Texas Medical Center complex.

On Thursday University Medical Center staffers took the wounded congresswoman to a deck at the hospital, where she breathed in the fresh air and felt the sun, trauma surgeon Peter Rhee said.

"I saw the biggest smile she could gather," Rhee said. "We are very happy to have her enjoying the sunshine of Arizona."

Giffords has been making progress nearly every day in her recovery from a bullet wound to the brain.

A gunman shot Giffords and 18 other people Jan. 8 outside a grocery store where she was meeting constituents. Six people died and the others wounded. All survivors, except Giffords, have been released from hospital.

The suspect in the attack, Jared Loughner, 22, of Tucson, is being held in federal custody.

Doctors ticked off other markers of the continuing improvement of Giffords, a Democrat from Arizona: She scrolled through an iPad, picked out different coloured objects and moved her lips. They are unsure whether she is mouthing words, nor do they know how much she is able to see.

Her husband, Houston-based astronaut Mark Kelly, believes she has tried to speak and can recognize those around her.

"I can just look in her eyes and tell," Kelly said at a final briefing Thursday at the Tucson hospital. "She is very aware of the situation."

He said he's hoping she'll make a full recovery, calling her "a fighter like nobody else that I know."

Sober outlook

The doctors who will help her offered a more sober outlook.

"Not everyone always gets 100 per cent restoration, but we help them to get to a new normal," said Carl Josehart, chief executive of the rehab hospital that will be the Arizona congresswoman's home for the next month or two.

In Houston, Dr. Gerard Francisco, the hospital's chief medical officer, will co-ordinate her care.

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Mark Kelly, right, talks about his wife, Representative Gabrielle Giffords, as Dr. Peter Rhee looks on during a Thursday news conference to update Giffords's condition at the University Medical Center in Tucson, Ariz. ((Tom Tingle/Arizona Republic/Associated Press))

"It's going to be a very big team that will address different impairments, but they will have to work together," he said.

First, they'll check her vital signs — make sure her blood pressure and heart rate are good. Then specialists ranging from physical and occupational therapists to speech therapists and psychologists will give a slew of tests to see what she can and cannot do.

The strength of her legs and her ability to stand and walk. The strength of her arms, and whether she can brush her teeth or comb her hair. Whether she can safely swallow on her own. How well she thinks and communicates — not just her ability to speak but also to understand and comprehend, Francisco said.

It's unclear if she is able to speak. And while she is moving both arms and legs, it's uncertain how much strength she has on her right side; the bullet passed through the left side of her brain, which controls the right side of the body.

Needs 24-hour care

Giffords will stay at Memorial Hermann until she no longer needs 24-hour medical care — the average is one to two months. Then she can continue getting up to five hours a day of physical and other rehab therapies on an outpatient basis, Josehart said.

"It's hard to speculate on the trajectory or course that any one patient will have," he said.

Despite the steady progress, Giffords has a long road to recovery. Doctors are not sure what, if any, disability she will have.

Sometimes, areas of the brain that seem damaged can recover, said Mark Sherer, a neuropsychologist at the rehab centre.

"Some of the tissue is temporarily dysfunctional, so the patient appears very impaired very early on after the injury," but may not be permanently damaged, he said.

"The last 12 days have been extraordinarily difficult for myself, my family, but not only us," Kelly said. "I think it's been very difficult for the city of Tucson, southern Arizona and our country."

Kelly added that Giffords would be proud of the way Tucson has responded. Memorials continued to grow Thursday outside the hospital, in front of her office and at the scene of the shooting.

"I know one of the first things Gabby is going to want to do as soon as she's able to is start writing thank-you notes," he said.