Reported cases of pertussis have increased since the mid-1970s. According to the Centers for Disease Control and Prevention (CDC), there were almost 20,000 cases in 2004 - the highest number of reported cases in more than 40 years. In addition, 39 percent of cases reported to the CDC in 2003 occurred in adolescents 10-19 years of age. Adolescents, in whom classic signs and symptoms of pertussis are often absent, may go undiagnosed and be the source of infection for susceptible infants and other family members.
"Pertussis is a serious and growing public health threat, and we are extremely pleased that the FDA Advisory Committee has provided a unanimous favorable recommendation for FDA approval of Boostrix," said Barbara Howe, M.D., vice president, Clinical Research and Development and Medical Affairs, Vaccines North America, GlaxoSmithKline. "If approved, Boostrix would add a pertussis component to the routine tetanus/diphtheria booster currently administered to adolescents - a population in which there is a significant disease burden."
In making its recommendation, the FDA Advisory Committee reviewed several clinical trials which included safety and immunogenicity data from one pivotal trial, which studied Boostrix in more than 3,000 adolescents in the United States, aged 10 to 18. The Phase III clinical trial showed Boostrix to be comparable to a U.S.- licensed Td vaccine [Tetanus and Diphtheria Toxoids] with regard to overall safety and immunogenicity. In addition, the use of Boostrix induced anti-pertussis antibody levels, which were statistically higher than those observed in infants following primary immunization with a DTaP vaccine (Infanrixâ) [Diphtheria and Tetanus Toxoids and Acellular Pertussis Vaccine Adsorbed] in whom efficacy against pertussis disease was demonstrated in a previous study.
In this observer-blinded, randomized, controlled, multi-center clinical trial, 4,114 healthy 10-18-year-olds were vaccinated with one dose of Boostrix or a U.S.-licensed Td vaccine. Each subject had completed his or her routine childhood vaccinations against diphtheria, tetanus and pertussis according to the U.S. recommended schedule. According to study results:
- In both treatment groups, > 99.9 percent of subjects had anti-diphtheria and anti-tetanus concentrations > 0.1 IU/ml, indicating seroprotection against diphtheria and tetanus
- In the Boostrix treatment group, the levels of anti-pertussis antibodies, anti-PT, anti-FHA and anti-PRN were measured and were statistically higher than pertussis antibody concentrations observed in infants, following primary immunization with a DTaP vaccine (Infanrixâ), in whom efficacy against pertussis disease was previously demonstrated
- The overall safety profile was comparable between the Boostrix and Td groups
"Adolescents are an important reservoir for the disease and often the source of infection for infants," noted Dr. Colin Marchant, adjunct associate professor, Boston University School of Medicine, Boston, MA. "Adding pertussis to the current tetanus and diphtheria booster shot for teens is a logical strategy to prevent this disease in adolescents - without additional injections - and may help reduce the risk of transmission to infants in whom pertussis can be deadly."
Background on Pertussis
Pertussis, commonly known as "whooping cough," is a highly contagious bacterial infection of the respiratory system that causes spasms of severe coughing. It is spread through airborne droplets of an infected person's cough or sneeze. The first symptoms of pertussis are similar to the "common cold" with a mild fever, runny nose and a cough. Symptoms generally progress to more severe coughing episodes, often with a high-pitched "whoop," followed by vomiting. Adolescents generally exhibit different symptoms of the disease, often without the classic "whoop," making it difficult to diagnose. However, for these older pertussis sufferers, severe coughing episodes can lead to vomiting, a hernia, or even a broken rib. These severe coughing episodes can last up to 100 days. While pertussis is threatening to all, this highly contagious disease can be deadly in infants who are too young to be fully immunized. Up to 90 percent of non-vaccinated susceptible household members may develop the disease when exposed to people infected with pertussis.
Pertussis, which is under-reported and under-recognized, is a common cause of prolonged cough illness in adolescents and adults. In fact, in a clinical study involving 442 adolescents and adults who had a cough-related illness for more than seven days, approximately 20 percent of these patients had laboratory-documented pertussis.
In addition to the public health threat pertussis poses, the disease also has economic repercussions. A cost-benefit analysis for the use of a pertussis booster vaccine in adolescents projected that vaccination of people in the U.S. ages 10-19 during a 10-year period would prevent up to 1.8 million cases of pertussis and save as much as $1.6 billion in direct and indirect costs.
"With nearly two million doses of Boostrix distributed worldwide since 1999, GlaxoSmithKline is extremely pleased that our efforts to develop a booster vaccine for pertussis in the U.S. have resulted in a favorable recommendation from the FDA Advisory Committee," said David M. Pernock, senior vice president Pharmaceuticals, Philadelphia & Vaccines, GlaxoSmithKline. "As a leader in combination vaccines, GlaxoSmithKline will be proud to introduce Boostrix as the first of a number of new and important candidate vaccines from our pipeline specifically targeted at preventing disease in adolescents."
Background on Diphtheria and Tetanus
Diphtheria is a serious disease that results in the death of approximately five to 10 percent of infected persons, with higher death rates (up to 20 percent) in persons younger than five and older than 40 years of age. Initial symptoms may include malaise, sore throat and low-grade fever. As the disease progresses, a membrane can form over the airway and result in respiratory obstruction which can lead to death. Other complications may include heart failure and paralysis. Most cases of diphtheria occur among unvaccinated or inadequately vaccinated persons.
Tetanus (lockjaw) is a severe, often fatal disease. The bacteria that cause tetanus are widely found in soil and the manure of many animals. Almost all reported cases of tetanus are in persons who have either never been vaccinated, or who completed a primary series, but have not had a booster in the preceding 10 years. Infants of unvaccinated mothers are at risk for neonatal tetanus. Early symptoms are lockjaw, stiffness in the neck and abdomen, and difficulty swallowing. Later symptoms may include fever, elevated blood pressure and severe muscle spasms.
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