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Biologics Licensing Application Submitted for Adacel Vaccine
Reported cases of pertussis, commonly known as whooping cough, clearly are on the rise in the U.S. In 2002, 9,771 cases were reported to the U.S. Centers for Disease Control and Prevention (CDC), the highest number of such reports in more than 30 years. Preliminary counts of pertussis reports for 2003 exceed 10,000, while reporting thus far in 2004 is at an even faster pace. However, it is estimated that only 12 percent of pertussis cases are actually reported and that under-reporting may be greatest among adolescents and adults.
"Pertussis continues to be an important public health issue, in part because adolescents and adults may not even be aware that they have the disease and that they can transmit it to vulnerable infants and younger children," said David R. Johnson, MD, MPH, director, scientific and medical affairs, Aventis Pasteur. "We've already had great success in the prevention of tetanus and diphtheria in the U.S. and believe that the introduction of a combination vaccine that also protects against pertussis in adults and adolescents will help to counter ongoing transmission of this disease."
A vaccine is currently available to protect children against pertussis up to 7 years of age. The diphtheria, tetanus and pertussis (DTaP) vaccine is generally administered in five doses between the ages of 2 months and 6 years of age. However, the vaccine does not offer lifelong protection against pertussis, and it is believed that immunity wanes by adolescence. While a tetanus and diphtheria booster immunization is available starting at age 11, a pertussis booster is not. The Adacel tetanus, diphtheria and pertussis vaccine will be referred to as a "Tdap" vaccine; the children's vaccine to prevent these same diseases is known as "DTaP." The pertussis components in Adacel vaccine are based on the acellular pertussis formulation in DAPTACEL(R), Diphtheria and Tetanus Toxoids and Acellular Pertussis Vaccine Adsorbed (DTaP vaccine), which was successfully introduced by Aventis Pasteur in the U.S. in 2002.
The regulatory submission for ADACEL vaccine is based on results of clinical studies involving more than 7,200 clinical trial participants. The vaccine has shown an excellent safety and immunogenicity profile. Adacel vaccine is currently approved and marketed in Canada and Germany.
Risk of Pertussis
Pertussis is a highly contagious, respiratory disease marked by severe coughing. Its common name, whooping cough, comes from the "whoop" sound children and adults make when they try to inhale during or after a severe coughing spell. There are both severe and mild forms of pertussis. Although pertussis can occur at any age, severe pertussis disease usually occurs in infants and young children who are at higher risk for severe pertussis-related complications and even death. While adults may not experience the debilitating effects of the disease that infants do, infected adults can easily transmit the illness to unimmunized and partially immunized infants and young children. Additionally, older adults (more than 55 years of age) may also be at considerable risk for death associated with pertussis.
Mild pertussis disease is difficult to diagnose because its symptoms are not as distinctive; usually a prolonged cough is present, but without the "whoop." One reason for the incomplete identification of pertussis may be that diagnosis of the disease in adults and adolescents is sometimes difficult because symptoms are often atypical.
Although infants and young children may experience mild pertussis disease, it is more often associated with adolescents and adults. Even in less severe cases, infected adolescents and adults can easily transmit the illness to vulnerable infants and young children who may experience complications associated with the disease, such as pneumonia, encephalitis and pertussis-related seizures.
"While older patients are often spared the debilitating effects of the disease, the fact that it may not be properly diagnosed and treated opens the door for spreading the disease," said Dr. Johnson. "Increased outbreaks in this country are an all too common reminder that we need to bring this disease under control."
About Tetanus, Diphtheria, Pertussis
Tetanus is a severe, frequently fatal disease caused by an exotoxin produced by bacteria (Clostridium tetani). The disease, characterized by generalized rigidity and convulsive spasms of skeletal muscles, causes paralysis, usually starts at the top of the body and works its way down. "Lockjaw," as the disease is sometimes called, is often the first symptom, followed by stiffness in the neck and difficulty swallowing. Muscle spasms may occur frequently, lasting for several minutes and persisting for up to a month. Symptoms of tetanus can appear anywhere from three days to three weeks after exposure to the bacteria and may be accompanied by fever, sweating, elevated blood pressure and rapid heartbeat. The bacteria that cause tetanus are widespread and are found in soil and in the intestinal tracts of animals and humans. It usually enters the body through a wound or opening in the skin. Virtually all of the cases of tetanus disease occurring in the U.S. are in adults not up-to-date with booster vaccinations.
Diphtheria is a disease caused by exposure to airborne bacteria (Corynebacterium diphtheriae) from an infected person and usually affects the tonsils, throat, nose and/or skin. It is passed from person to person by droplet transmission, usually by breathing in diphtheria bacteria after an infected person has coughed, sneezed or even laughed. It can also be spread by handling used tissues or by drinking from a glass used by an infected person. Symptoms usually appear two to five days after infection and begin very much like a common cold. However, symptoms can progress as a membrane grows and covers anywhere from a small patch to most of the throat, potentially blocking the airway. The infection releases a toxin that can lead to heart failure and paralysis, and if enough toxin is absorbed into the bloodstream, coma or even death can occur in as little as a week. Diphtheria occurs rarely in this country, but is occasionally imported from countries where it is endemic. Ongoing vaccination to protect against diphtheria continues to be recommended.
Pertussis, a highly contagious disease of the respiratory tract, is caused by exposure to bacteria (Bordetella pertussis) found in the mouth, nose and throat of an infected person. Pertussis is primarily spread by direct contact with discharge from the nose or throat of infected individuals. Classic, or severe, pertussis, as defined by the World Health Organization, consists of at least 21 days of cough illness (with the cough coming in spasms or paroxysms), associated whoops or post-cough vomiting, and culture confirmation. Mild pertussis is any laboratory-confirmed pertussis disease that is less than classic disease.
Pertussis can occur at any age. More than half the cases occur in adolescents and adults, while the majority of the remaining cases affect children under 1 year of age. For young children, pertussis disease can result in significant morbidity, hospitalization, serious long-term complications, and death.