Jacob Klonsky has been vaccinated right on schedule for most childhood diseases. But not measles or mumps.

Linda and David Klonsky, the 2-year-old's parents, don't trust the combined measles-mumps-rubella vaccine, or MMR, that's routinely given by pediatricians. That's because their nephew was diagnosed with autism soon after he received the MMR. Despite scientific evidence to the contrary, the Klonskys - and thousands of parents like them - believe there may be a link between the vaccine and the incurable developmental disorder.

"I'm not anti-vaccine, I'm anti-unsafe vaccine," says Linda Klonsky, a North Jersey homemaker. "I simply wanted my pediatrician to separate the measles, mumps, and rubella vaccines. It's safer that way."

Now, however, the Klonskys don't have that choice. Separate rubella vaccines remain available, but Merck, the New Jersey-based pharmaceutical giant that's the sole American manufacturer of both the MMR and the single vaccines, is no longer making separate vaccines for measles and mumps. That leaves the Klonskys and parents like them struggling for alternatives.

"We're at the mercy of the drug company," Klonsky says. "It really stinks. I know Jacob will need those immunizations to get into school, so sooner or later I'll have to give in and get him the MMR. But I don't want to."

Merck stopped making the separate, or monovalent, vaccines in 2001, but the halt is temporary, says Merck Vaccine spokeswoman Joyce Buford. The stoppage stems from problems in the company's vaccine manufacturing process uncovered that year, which forced Merck to shut down production and retool, resulting in vaccine shortages.

"Merck's priority was to make sure the required vaccines, like MMR, were back in full supply, and producing the single vaccines would have been at the expense of that," Buford says. "We hear the parents' wishes, and we intend to start producing the separate measles and mumps vaccines at some point. We just don't know when."

The state requires proof of protection against the three diseases for children entering school. Typically, that comes in the form of the MMR vaccine. The Centers for Disease Control and Prevention recommend that children receive their first MMR shot after their first birthday, and a second dose before kindergarten, usually between the ages of four and six.

The state grants exemptions to vaccination requirements, and while few invoke it, the number that do is rising. In the 2001-02 school year, 974, or 0.25 percent, of the state's new students received medical or religious exemptions from required immunizations, up from 0.06 percent in 1997-98 and 0.03 percent in 1990-91.

One Bergen County mother, who asked that her name not be used, says she plans to invoke the religious exemption because she's skeptical of the MMR's safety.

"I'm not convinced all the information we get from the medical community is thorough or unbiased," she says.

The religion she'll claim is the Congregation of Universal Wisdom, which was established in 1975 by four South Jersey chiropractors. One of its tenets states: "No member of the Congregation shall have injected, ingested, or infused into the body any foreign materials of unhealthy or unnatural composition."

Never mind that the Bergen County mom has vaccinated her two children against other diseases, violating a principle of her new church.

"When it comes to the health of my child, a little dishonesty is OK," she says.

Vaccines against measles, mumps, and rubella first arrived in pediatricians' offices in the mid-1960s and were bundled together in the MMR in 1971. Since then, the MMR has become the standard method of immunization against all three diseases.

Measles, mumps, and rubella have been eradicated in the United States. The only cases have resulted from visitors or recent immigrants bringing the diseases in. In New Jersey over the last seven years, there have been 15 measles cases, 26 mumps cases, and 22 cases of rubella.

Most parents who eschew the MMR vaccine generally do so because of fears over autism. The controversy was sparked by a 1998 British study that found the combination of mumps and measles viruses in the MMR may have contributed to children's autism.

Feeding such fears is the mistaken belief that the MMR contains thimerosal, a mercury-based preservative that has been linked to autism. Although the U.S. Food and Drug Administration has ordered vaccine makers to remove thimerosal from their products, it has never been an MMR ingredient.

Pediatricians and other health professionals routinely counsel that the MMR is safe.

"In my view, there is no controversy concerning the MMR," says Cory A. Golloub, chairman of Pediatrics at Chilton Memorial Hospital in Pompton Plains. "Studies have shown no association with autism."

A March 2001 report by the Institute of Medicine of the National Academy of Sciences concluded that "the evidence favors rejection of a causal relation ... between MMR vaccine and [autism]." Reports by the American Academy of Pediatrics, World Health Organization, and British health authorities came to similar conclusions.

But the Institute of Medicine report couldn't rule out "the possibility that MMR could contribute to [autism] in a small number of children."

Ray Gallup of Lake Hiawatha believes his son, Eric, falls into that category. Gallup says his son was a normal 14-month-old child when he received the MMR. Then, Gallup says, he watched Eric "regress into autism."

Today, Eric is a 6-foot-tall, 18-year-old man who, because of his condition, occasionally gets aggressive. In February, he attacked Gallup and bit his father's finger so badly it broke. Gallup, a 58- year-old accountant, wonders how long Eric can keep living at home.

"We paid the price for trusting what they said was safe," Gallup says.

Autism may be parents' main concern, but it's not the only one. Some believe that introducing so many toxins at the same time into a young system may be damaging. Others point to the unpredictability of a possible adverse reaction and the difficulty of tracing its cause to a particular component of the vaccine.

Still, the immunization industry is trending toward more combining. In January, GlaxoSmithKline began marketing Pediarix, a vaccine that, in one injection, protects against diphtheria, tetanus, whooping cough, hepatitis B, and polio.

GlaxoSmithKline is trumpeting the fact that without Pediarix, protection against those diseases takes nine shots.

"Most pediatricians don't want iceboxes full of a bunch of different vaccines," says Robert Sherrar, executive director of product safety for Merck Research Laboratories. "We want to get children protected against as many diseases as we can when we get them into the doctor's office."

For parents who question vaccines, however, convenience is outweighed by concern, and no alternative puts them completely at ease.

"No matter what I do, I feel like I'm betraying my child," says one North Jersey mother. "What if she gets sick from the vaccine? What if she doesn't get the vaccine and she gets sick with the disease? It's a real crap shoot. I hold my breath every time she gets a shot."

Providing a choice of vaccines could lessen parents' feeling that they're gambling with their children's health, says Peggy O'Mara, publisher of Mothering magazine, a champion of alternative lifestyles.

"What's frustrating is to have parents who take the time to research both sides of the issue, and then, with the lack of separate vaccines, there are no choices out there for them," O'Mara says.

Many skeptical parents report that pediatricians are impatient with their questions, and some say they switched doctors as a result.

"You feel like you're going up against a group of aliens who look at you funny for questioning vaccines," says Liz Corcoran, a Sparta mother of three who changed doctors over the vaccine issue. "Most moms don't even think about it. But if I don't look closely at what's going on, what kind of mother am I?"

This Article has been submitted by the Jeremy's Prophecy Dot Com team for informational and educational purposes. Jeremy's Prophecy Dot Com is a website dedicated to telling the story of Jeremy Jacobs, a character in the novel, Jeremy's Prophecy Dot Com.