Clinical Trial Shows Promising Results in Development of New Vaccine for Prevention of Life-threatening Infection in Newborns and Infants.

BELTSVILLE, Md.--(HealthWire)--Nov. 20, 1996--Promising results from a clinical trial of a polysaccharide conjugate vaccine for the prevention of group B Streptococcus (GBS) disease in newborns, young infants and adults have been announced today by the Brigham and Women's Hospital and Harvard University. The vaccine is based on technology exclusively licensed to North American Vaccine from Brigham and Women's Hospital, Harvard University, and the National Research Council of Canada. Currently, there is no vaccine approved or sold for the prevention of GBS infections in infants or adults. The GBS polysaccharide conjugate vaccine was tested in a clinical study held at Baylor College of Medicine under sponsorship by the National Institutes of Health. An article describing the study and its results has been published in the November 15 issue of the Journal of Clinical Investigation.

The safety and immunogenicity study was conducted by a group of clinical investigators led by Dennis Kasper, M.D. from Brigham and Women's Hospital and Harvard Medical School. The results of the study revealed that the GBS conjugate polysaccharide vaccine was well tolerated with minimal reactogenicity and no serious side-effects. In addition, antibodies elicited by immunization with the conjugate vaccine displayed protective activity against GBS in vitro and in vivo. In addition, the clinical investigators reported that the delivery of a GBS polysaccharide conjugate vaccine through maternal immunization may be a realistic approach to the prevention of perinatal GBS infection. The authors reported that antibodies transported through the placenta to the fetus may confer protective immunity even to infants born prematurely between 34 and 37 weeks of gestation.

"We are extremely pleased with the results of this clinical study which offers tremendous promise in the development of a vaccine against a life threatening disease affecting newborns, infants and adults" says Sharon Mates, Ph.D., President of North American Vaccine. "North American Vaccine holds numerous patents and patent applications relevant to all aspects of a GBS vaccine, which we believe makes us a world leader in the development of a safe and effective vaccine to prevent this serious disease. The company, together with Brigham & Women's Hospital, is now preparing for expanded trials to establish the safety and efficacy of a multivalent GBS polysaccharide vaccine." North American Vaccine holds an exclusive license to the technology underlying this vaccine and has expanded its technology base through internal research and development efforts.

Group B Streptococcus is a devastating disease and the most common cause of serious infections in newborns and young infants. Newborns are usually infected with GBS from the mother during the delivery process. Neonatal GBS infections occur principally during the first three months of life and can result in serious complications, including blindness, mental retardation, pneumonia, sepsis and permanent brain damage from meningitis. GBS infection in neonates has a mortality rate of approximately 5%-8%. GBS disease is also a prominent cause of peripartum maternal infections, causing an estimated 50,000 cases annually with a mortality rate of approximately 16%. Since there is no vaccine for the prevention of GBS disease, the Centers for Disease Control and Prevention has issued guidelines for detecting and treating GBS infections in pregnant women. These guidelines, which have been adopted by the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, include diagnostic testing during the third trimester and, for those infected, a course of intravenous antibiotics during and post labor.

This press release contains certain forward looking statements, which are made pursuant to the safe harbor provisions of the Securities Litigation Reform Act of 1995. Investors are cautioned that forward looking statements involve risks and uncertainties which may affect the Company's business and prospects, including without limitation, uncertainties relating to clinical trials, the requirement for regulatory approval of products by the FDA, nature of competition and effective marketing all as discussed in the Company's filings with the U.S. Securities and Exchange Commission.

North American Vaccine, Inc., is engaged in the research, development and production of vaccines for the prevention of human infectious diseases. North American Vaccine's news releases are available on the company's web site at http://www.nava.com. For further information contact: Antoinette Lipani-Solnick, at 301-470-6100.

CONTACT: North American Vaccine, Inc., Beltsville

Antoinette Lipani-Solnik, 301/470-6100