New Vaccines for Old Diseases

From the WebMD Archives

Sept. 18, 2000 (Toronto) -- Ear infections in children, bladder infections in women, and wracking coughs among teens may soon be distant memories. New vaccines, and older vaccines adapted for teens and adults, soon will be available to fight all of these conditions, according to presentations here at an international conference of infectious disease specialists.

Urinary tract infections are hardly life threatening, but they add $4 billion to annual U.S. health care costs. A major cause of these infections is a strain of E. coli that has learned to travel upstream to the bladder and even to the kidneys. Now a new vaccine promises relief for most of the 10 million U.S. residents who each year develop these bacterial infections.

"The focus of our efforts in vaccine development is to take a portion of the [bacteria] ... and use it as a [vaccine]," says Scott Koenig, MD, PhD, of MedImmune Inc., based in Gaithersburg, Md.

The first clinical trial of the vaccine enrolled 48 women. Most of the women had a little pain at the site of injection, but none felt bad enough to drop out of the study.

"We saw very good antibody responses," Koenig says. So far, immune substances taken from the blood of vaccinated women was strong enough to prevent bladder-disease-causing bacteria from attaching to human cells, in a test tube.

Koenig says that larger clinical trials are scheduled for later this year. One trial will test the vaccine in 90 women who have had three or more recurrent urinary tract infections; another will enroll 300 women who have no history of infection or who only get infections once in a while.

Far earlier in development is a vaccine that targets the bug that causes a type of ear infection called otitis media, the single most common cause of visits to the pediatrician and a $3 billion to $5 billion annual health care headache in the U.S. In the developing world, this bacteria, called Haemophilus influenzae, is also a significant cause of death from pneumonia.

Stephen J. Barenkamp, MD, and colleagues at the St. Louis University School of Medicine found that children who have recently recovered from otitis media have high concentrations of antibodies to a couple of different proteins on the bacteria.

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In chinchillas -- the best animal model for this type of infection -- a mixture of these specific bacterial proteins protected half the animals from infection by bringing about an immune response, and most of the animals that did get infected had lower levels of the bacteria in their ears.

There is an even further refinement of this vaccine, which uses these bacterial proteins in combination with another type of protein found on some of the bacteria.

"The thought is that we might be able to make a combination vaccine [with both of these types of proteins]," Barenkamp says. "We are just getting into clinical trials, but there is no human data yet."

While the otitis media bacteria is a major cause of chronic sinus infections in adults, Barenkamp tells WebMD that he is doubtful that the vaccine will offer an effective treatment for these patients. "I'm not convinced that adults would benefit from this vaccine," he says. "I think this would primarily be to prevent childhood infections."

Another conference presentation considered the use of an existing vaccine -- the 'whooping cough' vaccine -- in a new population. Scott Halperin, MD, of Dalhousie University in Halifax, Nova Scotia, notes that adults and adolescents are the most rapidly growing population affected by pertussis in the U.S., Canada, the U.K., and Europe.

Pertussis is the bacterium that causes whooping cough in children. In adults, it can bring about persistent coughing, without the telltale 'whoop' that you would hear from a child's immature respiratory tract. Nonetheless, it is still a problem for teens and adults. An outbreak this year in Victoria, British Columbia, was responsible for hundreds of diagnosed cases, and perhaps 10 times as many more not properly diagnosed.

"In adults the mean duration of cough is 40 days," Halperin says. "In adults and adolescents there is zero [death rate] -- but coughing and staying awake for three to four weeks is terrible and well worth preventing."

In addition to adult illness, there is also risk that adults -- especially teen mothers -- will transmit the disease to infants. There now are two different adult formulations of the vaccine. One is licensed in Canada and one in Germany; neither is currently available in the U.S.

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Despite this availability, too little is known about adult and adolescent pertussis to know exactly how to use the vaccine. Some would use the vaccine only in high-risk populations (people having children and their immediate families). Halperin prefers to immunize everybody, although he acknowledges that adult immunization poses practical problems.

WebMD Health News Reviewed by Gary D. Vogin, MD
© 2000 WebMD, Inc. All rights reserved.

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