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Asking how

Vaccine side effects probed

A few Stanford scientists are part of a vanguard seeking explanations for adverse reactions that occur following vaccination — which, rare as they are, cause great concern. The United States has a comprehensive, well-established system for assuring vaccine safety, says John Iskander, MD, the associate director for science of the immunization safety office at the Centers for Disease Control and Prevention. Typically, though, the agency estimates risk through analysis of adverse-events reports.

The goal of a small CDC program launched in 2001, the Clinical Immunization Safety Assessment network, is to take the knowledge to a new level: to figure out the mechanisms for how these undesirable side effects occur.

“CISA bridges the gap to understanding the one in 10,000, the one in 100,000, even the one in a million patients who experiences an adverse reaction,” Iskander says. “We want to understand the underlying biology of that to predict and prevent it.”

The rarity of severe adverse reactions makes studying them challenging, says Iskander. To help find sufficient numbers of these reactions, CISA, with a $2.5 million annual budget, partners with researchers at Stanford and five other medical centers — Boston Medical Center, Columbia University, Johns Hopkins University, Northern California Kaiser Permanente and Vanderbilt University — that have the volume of patients needed for meaningful study.

At Stanford, Cornelia Dekker, MD, professor of pediatrics, serves as principal investigator of CISA research. She has several CISA-funded projects under way:

  • • Packard Children’s pediatric infectious-disease fellow Barbara Pahud, MD, is working with Dekker to examine the vaccination records of patients reported to have encephalitis, an often fatal brain swelling that can be caused by any of more than 100 infectious agents. Cases of encephalitis following vaccination have been reported, says Pahud, but nobody knows how these cases are related to the vaccination, if at all. She’s working with the state health department’s California Encephalitis Project to identify any connections.
  • • Pediatric infectious-disease specialist Candice Smith, MD, and Dekker are studying rotavirus immunization of premature babies. These babies spend the first days of their lives in neonatal intensive care, where live vaccines are prohibited. So Dekker and Smith are looking at how the babies respond to a delayed immunization.
  • • One of CISA’s missions is to provide information to help vaccine providers manage adverse events, says Dekker. Toward that end, she is developing procedures for physicians caring for a patient who has a hypersensitivity reaction immediately after they’ve been vaccinated — for example a rash or, even more rarely, anaphylactic shock.
  • • The impact of vaccines on children with a chromosomal abnormality known as DiGeorge syndrome is the focus of another of Dekker’s studies. The mutation, called the 22q11.2 deletion, causes many birth defects, including heart anomalies, cleft palate and a faulty immune system. “It is really interesting to hear what the parents of these kids say that their doctors have recommended for the kids’ vaccinations,” says Smith, who also works on this project. Some doctors say they should receive no vaccinations, others say all but the live vaccines and still others recommend the full vaccination schedule. So the study will document immunization practices in these patients, and describe the occurrence of adverse reactions and vaccine-preventable diseases.

This kind of information can’t come soon enough for parents and the doctors who struggle to decide which vaccines special children should receive.






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