VATICAN CITY - Pope John Paul II was rushed to the hospital in an ambulance Thursday suffering fever and congestion from a relapse of the flu, the Vatican said.

The 84-year-old pontiff had the same symptoms of the breathing crisis that sent him to Gemelli Polyclinic on Feb. 1, a Vatican official said on condition of anonymity. On Wednesday, the pope made his longest public appearance since being discharged from the clinic two weeks ago.

Papal spokesman Joaquin Navarro-Valls said the pope was taken to the Rome hospital for “necessary specialized assistance and further tests.” He was taken by ambulance at 10:45 a.m., officials said.

Vatican officials played down the seriousness of the hospitalization, saying a patient of the pope’s age is always at risk from the flu. The pope also has Parkinson’s disease and crippling knee and hip ailments.

But aides said on condition of anonymity that the pope had a fever, congestion and had suffered a relapse of breathing problems.

The Italian news agency ANSA reported that the pope arrived conscious at Gemelli in a private ambulance. He was taken inside in a stretcher, the report said, and quoted people who saw him enter the hospital as saying his face looked “quite relaxed.” The news agency said he did not need a tube inserted into his windpipe to assist breathing.

A medical health bulletin was to be issued Friday morning, and no details on the pope’s health were expected to be released before that, the Vatican said. Thursday’s hospitalization was the pope’s eighth since his election in 1978.

The pope’s breathing problems can complicate the swallowing difficulties characteristic of Parkinson’s disease. The lack of coordination of the muscles involved make it easy for food or saliva to get into the lungs. That can cause a life-threatening pneumonia and is one of the most common causes of death among Parkinson’s patients.

Doctors sometimes bypass the throat by inserting a feeding tube directly into the stomach, both to help patients who have difficulty eating and to help prevent food going down to the lungs.

The muscle problems and the pope’s stooped posture also could make it difficult for him to head off infections by mustering a powerful enough cough to shake mucus out of the lungs.

Rome has been particularly cold, wet and windy in recent days. The pope has twice appeared at his open studio window to address crowds in St. Peter’s Square since his Feb. 10 discharge from the hospital, where he had been treated for breathing difficulties following a bout with the flu.

But the pope failed to show up Thursday morning for a scheduled meeting on new candidates for sainthood. No explanation was given for his absence and the ceremony went ahead, presided by the Vatican’s No. 2 official, Cardinal Angelo Sodano.

The Vatican released a letter the pope had sent for the canonization ceremony, saying that “for reasons of caution,” he had been advised to follow it from his apartment by closed-circuit television - an indication that the decision to take him to the hospital was made suddenly.

The pope had been convalescing after his hospitalization but had appeared to be making a rebound. At each new public appearance, he appeared stronger, more alert, and his voice was clearer.

On Wednesday, the pope wheezed and looked gaunt but managed to make his longest public appearance since leaving the hospital.

The Vatican originally had planned for the frail pontiff to address pilgrims in St. Peter’s Square from his apartment window but decided instead on a video hookup because of the rain and winds.

In all, the pope followed the audience for 30 minutes - the most he has appeared in public since returning from the hospital. Fully alert, he waved and gave his blessing at the end.

When John Paul was discharged from the hospital, the Vatican made clear he would decide on his schedule in consultation with his doctors.

Because of his ailments, there has long been speculation that John Paul might consider resigning. That debate was fueled during his earlier hospitalization when Cardinal Sodano declined to rule out that possibility, saying it was up to the pope’s “conscience.”

The Gemelli Polyclinic has taken in John Paul so often that it has been dubbed by the Italian press as “The Third Vatican,” after the seat of the Holy See on St. Peter’s Square and the pope’s summer residence in the town of Castel Gandolfo.

The hospital has a suite on the 10th floor that includes a chapel, kitchen and sleeping quarters for his longtime aide.

In 1981, the pope was shot in the abdomen and hand in a shooting attack by Turkish gunman Mehmet Ali Agca in St. Peter’s Square. He spent 20 days at Gemelli after undergoing surgery.

The Gemelli clinic was under tight security Thursday.