MONDAY, Nov. 28 (HealthDay News) -- Mistrust of childhood vaccines is causing some parents to request "alternative" schedules from doctors, either delaying or skipping some shots.

And a new study suggests that most pediatricians are willing to go along with these requests -- up to a point.

"Parents seem to be regularly requesting alternative childhood immunization schedules," noted co-author Dr. Douglas John Opel, an acting assistant professor in the University of Washington's department of pediatrics. However, he added, "there needs to be more research into the effectiveness and safety of these schedules."

The report is published in the Nov. 28 online edition of Pediatrics.

The issue of parents ignoring standard guidelines on childhood vaccination schedules is worrying to many experts. One study, published in the November issue of Pediatrics, found that more than one in 10 parents in the United States do not follow recommended vaccination guidelines for their children, opting instead for an "alternative" schedule that could involve skipping doses or delaying shots.

In that study, 13 percent of parents surveyed reporting using an alternative schedule. Of these, more than half (53 percent) refused certain vaccines and/or delayed some vaccines until a child was older (55 percent). And 2 percent of parents refused all recommended vaccines.

Some of the distrust of childhood vaccines stems from rumors that immunization might give rise to certain medical conditions. For example, one study published in The Lancet in 1998 suggested that the measles-mumps-rubella (MMR) shot might help trigger autism. That work was later discovered to be fraudulent, however, and the journal has since retracted the study.

The new research sought to determine physicians' attitudes to parents' requests for alternative vaccination schedules. To do so, Opel's team examined online survey data for 209 Washington state pediatricians. They found that 77 percent of the doctors had encountered parents who had asked them to alter a child's vaccine schedule in some way.

Close to two-thirds of the pediatricians (61 percent) said they were usually comfortable with providing an alternate schedule, if asked. But only 4 percent said they would offer any change to the schedule without prompting from a parent first.

However, there were three shots that doctors were most loathe to skip or delay. These included the haemophilus influenzae type b vaccine (Hib), which protects against a bacteria that can cause pneumonia; the pneumococcal conjugate vaccine (PCV), which also shields against pneumonia and meningitis; and the diphtheria, tetanus and acellular pertussis (DTaP) combo vaccine, which protects against three potentially deadly infections.

"These vaccines protect the child from diseases that are still common, like pertussis [whooping cough], and have severe consequences if a child catches it, like meningitis," Opel said.

The findings suggest that pediatricians are trying to strike a delicate balance in caring for children while listening to parents' concerns, he added.

"They are trying to respect a parent's decision-making authority and maintain a therapeutic alliance with them by not being rigid when parents request an alternative schedule," Opel explained. "Yet at the same time, they are also trying to honor their obligation to protect the child's health by standing more firmly on those vaccines that prevent diseases that a child is most likely to catch or suffer severe consequences from if they do catch it."

Dr. Michael Brady, chairman of the American Academy of Pediatrics' committee on infectious disease, said the study provides insight into how pediatricians are responding to vaccine-hesitant parents.

Agreeing with these requests may not always be wise, he added. "The pediatricians who agree to utilize alternative schedules are missing a tremendous opportunity to inform parents about the value and safety of vaccines and the current vaccine schedule," he said.

He also believes that parents' fears about the so-called "over-vaccination" of kids are misplaced.

"Children who are receiving multiple vaccines at one visit in 2011 are actually being exposed to fewer vaccine antigens than they were in the 1980s," he noted. "Our immune systems can handle multiple vaccines at the same visit very well."

There have also been very rigorous safety studies done before and after approval of childhood vaccines, to verify their safety when given alone or in combination, said Brady, who also chairs the pediatrics department at Nationwide Children's Hospital in Columbus, Ohio.

"However, there is no such data for the alternative schedules [that parents might request]," he said. "Parents who ask for the alternative schedules because they believe that they are safer are asking for schedules that haven't been evaluated. They may place their child at risk for a serious disease if they postpone these vaccines beyond the period of greatest risk."

Also,such schedules increase the likelihood that some doses will be skipped, because the more visits needed to receive all of the necessary vaccines, the greater the risk that some visits and some vaccines will be missed, Brady added.

More information

For more information on kids' vaccinations, visit the U.S. Centers for Disease Control and Prevention.