WEDNESDAY, Oct. 12, 2005 (HealthDay News) -- A vaccine for pertussis (whooping cough) that's normally only administered in young children is also highly effective in adolescents and adults, new research shows.
Experts believe that giving the vaccine to this older segment of the population would not only reduce their disease burden, but would also decrease the risk to young children, who tend to experience the illness more severely.
The finding is published in the Oct. 13 issue of the New England Journal of Medicine, and will likely translate almost immediately into clinical practice, experts noted.
"It will be brought on board very quickly," said Dr. Lawrence Friedman, director of the division of adolescent medicine at the University of Miami School of Medicine. "All of the major organizations will be endorsing it if they haven't already." Friedman was not involved in the study.
The American Academy of Pediatrics' (AAP) committee on infectious diseases, for one, has spoken out in favor of using the vaccine in older individuals. "The AAP board should accept it without any difficulty," said Dr. Joseph Bocchini, chairman of the committee and chief of pediatric infectious diseases at Louisiana State University Health Sciences Center in Shreveport. "This is a good step in attempting to control the spread of the organism among adolescents, to reduce the burden of disease in adolescents, as well as to protect younger children."
Two adult formulations of acellular pertussis vaccines combined with diphtheria and tetanus vaccines (dTap) are already licensed in North America. The adult pertussis vaccine contains only one-third the amount of acellular pertussis and diphtheria toxoids compared with the children's vaccine and shares its good safety record.
"It's not a big deal adding it. It's safe," said study author Dr. Joel I. Ward, a professor of pediatrics at UCLA School of Medicine. "We're hoping to get a big public health kick out of expanding its use because it is so safe."
Pertussis is a highly contagious, potentially fatal bacterial disease that affects the respiratory system. It produces coughing fits that may end in the signature "whooping" sound.
Before widespread vaccinations began about 50 years ago, pertussis was most common in infants and young children. Now that most children are immunized before school age, a higher percentage of cases are seen among teens and adults. In fact, during the 1990s, the number and proportion of pertussis cases in adolescents and adults more than doubled in the United States and Canada.
"The problem has been one of perception," Ward said. "People tend to think of whooping cough as a disease of young infants and children, but the reality is that most of the disease is now occurring in adolescents and adults because they didn't get the vaccine or because it wore off."
"Most of the disease that children get they get from adults," he added. "This is the one disease that works backward. Instead of kids infecting us, adults lose their immunity and infect kids."
But older individuals tend not to get as sick.
"Older people who get pertussis may think they have a bad cold with a cough and don't necessarily get treated," Friedman explained. "They don't even know what they have is contagious, and very often inadvertently give it to a baby who hasn't been immunized or a child who hasn't fully completed the series of shots and, in babies, it's deadly."
For this study, 2,781 participants aged 15 to 65 were given either a dose of tricomponent acellular pertussis vaccine or a hepatitis A vaccine (as a control) and followed for a median of 22 months.
In all, there were 10 cases of laboratory-confirmed pertussis -- nine in the control group and one in a person who had received the vaccine. This translated into a vaccine protection rate of 92 percent.
"We have a vaccine that's proven very safe and effective in children, and our study shows it works just as well, if not better, in adults, and two companies have come out with this new, improved adult vaccine," Ward said.
One complication in translating these findings into real-world practice is the fact that the study used a vaccine containing only a pertussis component, as opposed to the licensed vaccines that contain pertussis along with diphtheria and tetanus.
"If an adolescent has already gotten diphtheria and tetanus, because pertussis is only available as dTap, the recommendation is to wait at least five years to get the dTap," Bocchini said. "That will have an impact on how frequently the vaccine will be given."
More information
The U.S. Centers for Disease Control and Prevention has more on pertussis and pertussis vaccinations.
