Biotechnology is working to make baby shots obsolete

Experts explore new vaccines during the 31st National Immunization Conference

On the horizon are vaccine technologies that would have been considered science fiction just a decade ago. Today, leading researchers reported on these technologies during the closing scientific session of the 31st National Immunization Conference held here.

From synthetic DNA to bioengineered edible vaccine-containing plants, biotechnology is helping public health officials simplify a childhood vaccination schedule that is so full, sometimes three or four shots are required in a single medical visit.

America's childhood immunization schedule has undergone several major changes recently, now requiring children to receive as many as 12 to 16 shots by age two. Since, 1990, health officials have added vaccines to the schedule to protect infants from a form of severe meningitis (Haemophilus influenzae type b), hepatitis B, and chickenpox. Last year, existing polio and pertussis vaccines were replaced with improved and safer vaccines.

"We are concerned about the complexity of the childhood immunization schedule and the number of doses and injections required," said Walter A. Orenstein, M.D., director of CDC's National Immunization Program. "Its complexity is a tribute to our ability to prevent ever more infectious diseases but it stresses our vaccine delivery services. Both parents and health care providers are reluctant to have infants receive more than three needle sticks during a health care visit. This could mean more visits would be required to complete the schedule."

Instead, health officials are turning to science to simplify the schedule. "Combination vaccines will help reduce the number of injections and, possibly, the number of visits. But as we add new vaccines to prevent even more infectious diseases, the challenge continues," Orenstein said.

A legendary figure of mid-20th century immunization, Hilary Koprowski, M.D., professor of microbiology and immunology, of the Biotechnology Foundation, Thomas Jefferson University, developed the first live attenuated polio vaccine to be tested in human trials in 1950. Today, Koprowski explained to 2,000 health care professionals attending the immunization conference what shape future vaccines may take. According to Koprowski, edible plants may be engineered to become vaccine factories, potentially reducing the costs to manufacture vaccines.

Koprowski detailed work he has done with engineered tomato plants that have expressed a gene which coats the outer surface of the rabies virus. According to Koprowski, efforts at mass immunization of humans against rabies in developing countries is hampered by the relatively high cost of vaccine production. The ideal plant-based oral vaccine would be produced in an edible plant which is consumed fresh by the target population.

In addition to edible plants, researchers discussed progress on vaccines that have been enclosed in microscopic capsules, permitting them to be released over time to avoid the need for boosters, or to be taken orally.

"These are wonderful fruits of the biotechnology revolution," said Orenstein. "Almost a century passed between the development of the very first vaccine to prevent smallpox and the second one for rabies. Today, the pace is quickening and in the next few years we expect several more diseases to become preventable by vaccines."

Vaccines expected to become available in the Untied States in the near future include an improved vaccine for Streptococcus pneumoniae, and new vaccines for lyme disease and rotavirus diarrhea. In the United States, rotavirus diarrhea results in 750,000 doctor's visit, 100,000 hospitalizations, and 100 deaths among children under five years of age. This vaccine will be given orally.

Immunization levels today are the highest ever for children 19-35 months of age. And the incidence of most vaccine-preventable diseases are the lowest ever. During the 31st National Immunization Conference this week, participants explored latest research and policy issues related to vaccine-preventable diseases and immunization. To speak to an information specialist or to receive information materials about vaccine-preventable diseases, contact CDC's National Immunization Information Hotline at 1 800 232-2522 (English) or 1 800 232-0233 (Spanish).

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES