Pope John Paul II's (search) condition is improving and he has not suffered any more breathing spasms, the Vatican said, but the 84-year-old pontiff may have to spend up to a week in the hospital to fully recover.

In a sign that the pope's health had stabilized, papal spokesman Joaquin Navarro-Valls said the Vatican would not issue another medical bulletin until Friday. The Holy See has said the pope would spend a few more days at the Gemelli Polyclinic (search) hospital.

"The Holy Father's general and respiratory conditions show a positive evolution. The pope has rested well" with no repeat of the breathing spasms that sent him to the hospital Tuesday, Navarro-Valls said. "He rested well all night, and the laboratory tests that were made give a satisfactory result."

John Paul was running a slight fever, he said.

Navarro-Valls did not say exactly how long the pope would remain hospitalized, but he told reporters: "In my personal experience, when I've had the flu, it lasts a week."

Hospital spokesman Nicola Cerbino said the pope was being attended by a team of three doctors — his personal physician, the clinic's emergency department director and an ear, nose and throat specialist.

The pope is "recovering well," said Cardinal Angelo Sodano, who, as secretary of state, is the Vatican's No. 2 leader.

He told private TV Canale 5 that the pope's breathing problems could have been handled at the Vatican, where the pope had been laid up since Sunday evening with the flu. "But the Holy Father, as everybody, entrusts himself to the doctors," and the decision was made to hospitalize him, he said.

The Vatican said the pope had suffered spasms of the larynx, making it difficult for him to breathe, and he had an inflamed windpipe.

The clinic was calm overnight, though police stayed on alert. Before dawn, lights switched on in the clinic's 10th floor, where the pontiff is staying in a special papal suite.

Apprehension over the fate of the leader of the world's 1 billion Roman Catholics and one of the globe's best-known figures triggered an outpouring of well-wishes.

Poles prayed for him in the church where he was baptized in Poland, while Mexicans gathered in churches to light candles. Franciscan friars in the crypt of St. Francis Basilica in Assisi, Italy, asked God to help the pope in his suffering, while Catholic high school students in Pensacola, Fla., attended Mass in their gymnasium.

"If anything happens to him, God forbid, there would be a great loss to the world," said Bishop John H. Ricard, who heads the Pensacola-Tallahassee Diocese and celebrated the Mass. "So we are going to spend a great deal more time in prayer."

Polish President Aleksander Kwasniewski telephoned the pope's personal secretary Thursday and sent a letter wishing John Paul "a lot of strength in conveying to the world your message of peace and hope."

Mehmet Ali Agca, imprisoned in Turkey after shooting the pope in St. Peter's Square in 1981, sent a handwritten letter through his lawyers wishing the pope "a speedy recovery." The clinic treating John Paul is the same one where he was treated for his gunshot wound to the abdomen.

While anyone with the flu can develop respiratory complications, the elderly are especially vulnerable. Doctors also must guard against life-threatening complications, like pneumonia.

The Vatican declined to say whether the pontiff had a flu shot, but a Vatican official said it was "probable" because all employees of the Holy See were offered them.

Cardinal Javier Lozano Barragan, head of the Vatican's health care office, told Associated Press Television News that the pope's stooped posture keeps his lungs and diaphragm in a crushed position, a chronic obstacle to proper breathing.

Keeping the pope hospitalized will afford "many means to stay ready for any complications," he said.

John Paul, battling Parkinson's disease as well as hip and knee ailments, has been in weak health for many years. But a leading Italian cardiologist, Attilio Maseri, who has treated the pontiff during previous hospitalizations, said the pontiff has two enviable factors on his side.

"He has exceptional cardiovascular function, guided by exceptional willpower," Maseri, now based in Milan's San Raffaele hospital, said on state TV early Thursday.

"If he overcomes the respiratory problems he's suffering, he'll certainly be able to go back doing what he was doing before."

On Thursday, about 50 people — mostly doctors in starched white uniforms — attended the hospital's daily Mass, which was held for San Biagio, patron saint of the throat.

"We are praying for John Paul II so that he can be strong, courageous and full of hope," said Decio Cipollini, who presided over the Mass.

Although age and chronic health problems have slowed the pontiff considerably from his whirlwind pace during the early years of his 26-year-old papacy, John Paul has kept a remarkably strenuous pace.

His average week is spent working on documents, making appointments, meeting world leaders and appearing before the public at least twice a week.

American Cardinal James Francis Stafford, who is based at the Vatican, said church officials were working with concern and a spirit of prayer during the pope's absence.

"We don't know how things will turn out — the Holy Father is 84 years old," he said, quoted in La Repubblica newspaper. "We don't know what trials God has prepared for him."