The way to cool the hot debate on vaccine safety is to turn to science and get the facts, and here, there is reason for optimism. Last August, the National Institutes of Health embarked on an effort entitled "Research to Advance Vaccine Safety," involving five of its institutes plus the CDC. The operating premise: Vaccines are of vital importance to human welfare, and new and better technology enables researchers to address as never before gaps in knowledge about how to use them more safely and effectively. Areas the NIH wants to see tackled include:
Vaccine response. Vaccines do more than stimulate antibodies. Yet there is scant research on the way the complex networks of specialized white blood cells and immune chemicals behave in response to the currently licensed vaccines and their assorted nonvaccine components. Reactions vary among children and those of different ages, and sometimes, vaccines can induce overly sensitive immune reactions. Studies showing that early childhood vaccination may promote chronic allergies, for example, beg for further research.
Susceptible groups. The recognition that vaccines can be unsafe for some children made headlines last spring when experts determined that Hannah Poling, who had an unknown mitochondrial disorder, suddenly and dramatically developed autism as a toddler in reaction to nine immunizations administered at once, validating many parents' concerns. Recently, serious complications from the new smallpox vaccine have been tied to specific gene variations, and there is ongoing concern that rheumatoid arthritis and other autoimmune conditions have been triggered by the hepatitis B vaccine in those with genetic susceptibility. The NIH wants to identify risk factors and biological markers predictive of adverse reactions, which could protect vulnerable groups and allow better clinical trials.
Vaccine schedules. The one-size-fits-all vaccine schedule has served the public well but has yet to be tested for optimal efficacy and safety. The NIH proposes comparisons of the immunologic and physiologic effects of different combinations of vaccines administered on different schedules. Supporting this need is a 2008 Canadian study that found that delaying the diphtheria, pertussis, and tetanus vaccination a few months cut the risk of childhood asthma by 50 percent.
Immune capacity. As infants leave the womb's sterile environment, their immune system is virtually a blank slate, soon molded by generally benign and natural exposures—to pollen in the air, proteins in food, microbes on their mother's skin. It's assumed the little ones can handle with the same ease a sudden and concentrated exposure to the less benign antigens in vaccines. Research on the capacity of the young immune system to do so needs further investigation, particularly with the flood of new vaccines on the horizon.
Dr. Healy formerly headed the NIH.