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Polio vaccine comes full circle; Controversy: After years of debate, experts choose safer injections over oral vaccines

THE BALTIMORE SUN

A generation after children lined up for sugar cubes that promised protection from polio, doctors are returning to injections to prevent rare cases caused by the oral vaccine.

It's a move that might well have outraged Dr. Alfred Sabin, father of the oral polio vaccine, who argued bitterly against the injected vaccine championed by his scientific rival, Dr. Jonas Salk.

But public health authorities say the time has come to move away from the Sabin vaccine in the United States, capping a debate that's simmered within public health circles for years. The move says as much about the vaccine's success in subduing polio as it does about its little-known danger.

Since the late 1970s, fewer than 12 cases of paralytic polio have occurred each year in this country, a testament to the oral vaccine's ability to control a disease that crippled a president and put thousands of victims in leg braces and iron lungs. But in a cruel twist, the few cases that still occur are caused by the vaccine itself.

Doctors for many years accepted the risk because the vaccine prevented so many more cases than it caused. When tragedy struck, however, parents were dumbfounded.

"It was devastating and frustrating and ultimately caused me a lot of anger," said John Salamone of Oakton, Va., whose 8-year-old son, David, contracted polio from a vaccine when he was an infant. "It was like a dirty little secret: Nobody told you there were going to be sacrificial lambs."

The American Academy of Pediatrics, which published new recommendations in January, is calling for a sequence of two injections followed by two doses of either vaccine. But the group expects to suggest an all-out switch to injected vaccine by 2001.

The injected vaccine is a strengthened version of the original Salk vaccine, hailed as a miracle of science when it was introduced in 1954 -- two years after the nation's worst polio epidemic. Made from killed virus, the vaccine is incapable of causing infection if made correctly.

In contrast, the oral vaccine contains a live, weakened virus that boosts immunity in virtually everyone but, in an unlucky few, triggers the disease.

Polio is a viral infection, spread largely through the intestinal tract, that attacks the nerves that control muscles. In most victims, it causes flu-like symptoms and sometimes a temporary paralysis of the legs or arms. In severe cases, patients are permanently paralyzed.

A half century ago, Salk and Sabin debated the merits of their vaccines, but Salk's was available first.

Almost overnight, the disease that filled hospital wards began to retreat from the U.S. landscape.

The number of new cases declined from more than 50,000 when the vaccine was first introduced to less than 1,000 by 1960. It was replaced in 1962 by Sabin's oral vaccine, which held several advantages.

The first was obvious: Children hated shots, but didn't mind a vaccine that came on a sugar cube or in a squirt of sweet liquid.

To scientists, a second reason was perhaps more compelling. People who took the oral vaccine harbored a protective virus that could be passed to others through the environment. As a result, someone who never took the vaccine could become immunized through contact with somebody who did.

But there would be victims.

Vaccination, fast paralysis

David was 6 months old when Salamone and his wife, Kathy, took him to a pediatrician in 1990 for his second polio vaccination. They had no reason to believe the vaccination was anything but routine, even when David developed a fever and a rash two days later.

Two weeks after his doctor's visit, David woke up one morning paralyzed from the waist down. "He couldn't turn over," Salamone said. "He could only move his head back and forth."

His doctors in Washington were stumped, saying only that he suffered from nerve damage of unknown origin. David's mother was first to suggest polio; the sequence of events couldn't be ignored, and David's symptoms were classic.

"The doctors pooh-poohed her," said Salamone. "They said it wasn't possible. They said that because they had never seen a case."

David regained the use of his left leg but not his right, which became withered. He was fitted for a leg brace, and learned to walk with a wobbly gait that resembles that of "a drunken sailor," his father said.

Aside from his paralysis, David developed arthritis and an unending series of infections. He lived on antibiotics. At Georgetown University, doctors discovered he was born with an immune system disorder that left him defenseless against ordinary viruses. That, they concluded, made him vulnerable to live vaccine.

Only one in 12 million children who take the oral polio vaccine develop the disease from it. A quarter of the unlucky victims are, like David, born with immune disorders that take about a year to emerge. Until then, parents and doctors have no reason to believe the children are at risk.

The rest include infants who catch the vaccine virus from other children, often siblings, who were recently vaccinated. There have even been adults, including Lt. Gov. John H. Hager of Virginia, who contracted polio while changing a baby's diapers.

What makes otherwise healthy people vulnerable to the weakened virus is a question that still puzzles doctors.

"This is the dilemma with many diseases," said Dr. Neal Halsey of the Johns Hopkins School of Public Health, who heads the infectious disease committee of the American Academy of Pediatrics. "Why is it that 1 in 10,000 children will get encephalitis but 9,999 don't? We don't really know."

The fact that vaccine-caused cases were rare didn't matter to parents like Jane Thompson of Parkville, whose daughter, Laura, developed polio when she was 10 months old. After taking the oral vaccine, she stopped crawling and never learned to walk.

'Wasn't suppose to happen'

"We thought the vaccine was safe," said Thompson. "It was just one of those things that wasn't supposed to happen." Laura died in 1990 from a brain infection caused by an underlying immune disorder. The Thompsons later had three boys, but made sure they received inactivated polio vaccine even though they had healthy immune systems.

The Salamones organized a national organization, Informed Parents Against Vaccine Associated Paralytic Polio, and began lobbying to change vaccination policies. In 1996, several other parents joined him in testifying before the CDC, which was already considering a change.

Halsey, who was also an adviser to the CDC, had already concluded that the time had come to switch from the Sabin vaccine. "It was the right vaccine, but the equation had changed." He became a driving force behind the new policy.

At first, authorities were reluctant to force another injection upon children, who already endured injections against measles, tetanus and other illnesses. They also feared it would send the wrong message to developing nations, where the oral vaccine remains the weapon of choice in a worldwide eradication campaign.

The fact that the live vaccine spreads from person to person also made it the best way to maintain high levels of protection in poor communities in the United States, where immunization rates often lag, some critics said.

"Let's face it, no vaccine is 100 percent safe," said Dr. Donald A. Henderson, former dean of the Johns Hopkins School of Public Health, who has argued against the changes. "If you have a child with pneumonia and give penicillin, you can end up with a fatal penicillin reaction."

But parents were putting a human face on the problem of vaccine side effects, and their efforts paid off.

Widening support

The new recommendations appear to be taking hold. "Most of the parents are pretty happy with it," said Dr. Daniel J. Levy, an Owings Mills pediatrician and local spokesman for the American Academy of Pediatrics.

"Even though the risk is only 1 in 12 million that a child will get polio from the oral vaccine, to reduce the risk is a good thing."

Perhaps nobody is more satisfied than Dr. Darrell Salk, who advocated shifting to the enhanced version of the vaccine his father created. The elder Salk, who died in 1995, helped develop the updated vaccine.

Said Darrell Salk, vice president of a Seattle biotechnology company: "I'm pleased and he would be pleased."

Pub Date: 3/16/99

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