New Pertussis Vaccine Offers Prevention Alternative
by Rebecca D. Williams

As school bells ring this fall, the country's 3.3 million first-graders will  
clutch new Ninja Turtle lunch boxes and brightly colored backpacks. But       
before they enter classrooms, many will receive something new at the          
doctor's office as well--a safer pertussis vaccination.

Approved by the Food and Drug Administration last December, the new vaccine   
for pertussis, or whooping cough, offers immunity with fewer side effects     
than the older version, which caused some concern among physicians and        
parents.

"I think most physicians would like to see all of the reactions eliminated    
completely," says Donald Schiff, M.D., a spokesman for the American Academy   
of Pediatrics and a pediatrician at Denver Children's Hospital.

Developed in Japan about 10 years ago, the new vaccine is distributed by      
Lederle Laboratories of Wayne, N.J.

The pertussis vaccine is given in combination with diphtheria and tetanus     
vaccines in a series of five DTP shots between 2 months and 6 years of age.

The new vaccine is approved for the last two doses of the
series. Children getting it must be at least 15 months old because it has     
not yet been tested adequately in younger children.

It is younger children, however, who most often react severely to the old     
vaccine.

"The new vaccine does not relieve those who are most anxious about it--the    
parents of infants," says Schiff.

Fewer Side Effects

In about half of all children, especially infants, the traditional pertussis  
vaccine causes some uncomfortable side effects, such as swelling and          
soreness at the site of the shot, fever, and inconsolable crying several      
hours later.

For a very few others, however, the side effects are much worse. They         
include shock, convulsions and seizures. The vaccine has even been blamed     
for some cases of brain damage, but this association has not been proven.

The new vaccine has fewer common side effects. The incidence of severe side   
effects is still not known, however, since they occur so rarely. Hundreds of  
thousands of children will have to be vaccinated before doctors can document  
these.

In theory, the new vaccine should be much safer. Instead of being made like   
the old vaccine from whole pertussis bacterial cells that have been killed,   
the new acellular vaccine is made only from parts of pertussis bacteria that  
evoke protective immune responses.

Although the new acellular vaccine is available, not all eligible children    
need it. Many children tolerate the whole-cell vaccine just fine, and it is   
less expensive than the new one. Parents should check with their children's   
doctor about which vaccine is right for them.

In any case, children younger than 15 months should still be given the old    
vaccine unless their doctors recommend otherwise.

"It's important to realize that while there is a new vaccine, the old         
vaccine is very good, too," says Drusilla Burns, Ph.D., a research chemist    
in FDA's Laboratory of Pertussis who is involved in pertussis research and    
helped review the new vaccine.

"The whole-cell vaccine has served us very well," she adds. "It has some      
relatively minor adverse reactions, but the more severe reactions are still   
a matter of discussion."

The American Academy of Pediatrics and pediatric societies in Canada and      
Great Britain have stated that the vaccine is not a proven cause of brain     
damage.

And, while the risk of seizures from the whole-cell vaccine is about 1 in     
1,750, numerous studies have shown there's no evidence those seizures will    
permanently harm the child or increase his or her chance of developing other  
seizure disorders, such as epilepsy, later.

For most children, the benefits of the whole-cell pertussis vaccine far       
outweigh its risks.

Deadly Disease

Whooping cough is highly contagious and deadly. It causes mucus to build up   
in the lungs, making the child gasp and "whoop" for air every few minutes     
for two to three weeks.

The spasms may bring on vomiting, pneumonia, and sometimes brain              
hemorrhages. Spreading through droplets of moisture expelled by coughing,     
whooping cough bacteria will infect up to 90 percent of unvaccinated people   
exposed, especially young children. Both the old and new vaccines protect     
about 80 percent of children exposed to the disease, and the remainder have   
mostly mild cases.

Before the first vaccines were developed in the mid-1940s, whooping cough     
struck about 265,000 children annually in the United States and killed 7,500  
of them, more than all other contagious diseases combined.

Since then, pertussis cases have dropped drastically in the United States to  
about 4,500 cases and 10 deaths in 1990, according to the national Centers    
for Disease Control.

If this country stopped requiring pertussis vaccination, whooping cough       
would undoubtedly become epidemic again. This happened in the 1970s in Great  
Britain, Sweden and Japan, where vaccination was either suspended or slowed   
because of safety concerns.

No completely effective treatment for pertussis exists. According to CDC,     
about 1 percent of whooping cough victims under 2 months old will die,        
especially if pneumonia develops.

The key to protecting children from pertussis, then, is vaccination. Studies  
are under way in several countries to test the new acellular vaccines in      
younger children and infants.

The hope is that, not too far in the future, when a new school season opens,  
all children will be vaccinated against pertussis without any ill effects.    
And whooping cough, once thought of as a common childhood disease, will be    
remembered only in history books. n

Rebecca D. Williams is a staff writer for FDA Consumer.
FDA Leads Research

FDA's Laboratory of Pertussis is a world leader in research on pertussis,     
also known as whooping cough. Its scientists have made major contributions    
to the development of new "acellular" pertussis vaccines, so-named because    
they're made from soluble components, rather than whole pertussis bacterial   
cells that have been killed.

Through basic research, the laboratory has isolated and characterized         
virulence factors (the disease-causing substances) from Bordetella            
pertussis, the bacterium responsible for pertussis. These factors are         
important components of the various acellular vaccines.

Laboratory of Pertussis scientists have proposed vaccine formulations and     
developed manufacturing methods and laboratory models to evaluate potential   
vaccines before they are tested in children. They have contributed            
significantly to clinical studies and to the methods used to measure          
immunity in vaccinated patients.

"Scientists conducting research basic to the development of the vaccines are  
better able to advise manufacturers and train public health authorities and   
employees of vaccine producers," says Charles R. Manclark, Ph.D., chief of    
the Laboratory of Pertussis. "In so doing, these scientists expedite the      
steps to clinical use of new vaccines. But most important of all, basic       
pertussis research provides tools and knowledge that permit us to reexamine   
and understand the disease. These studies, for instance, provide information  
on the role played by older children and adults as reservoirs of disease and  
sources of infection for the very vulnerable infant."

Related research may help develop vaccines that prevent infection as well as  
disease, says Manclark, and may change how new vaccines are used. Currently   
being considered are the use of vaccines in adolescents and adults and the    
use of maternal antibodies to protect newborns.

Another area under intensive study in the Laboratory of Pertussis is the      
concept of oral immunization with living microbial vectors and                
microencapsulation vectors, substances that carry vaccine components in       
microspheres and release them gradually. Oral immunization--besides being     
more acceptable to patients--doesn't require syringes, needles, or highly     
trained personnel.

"New vaccines used in ways that more effectively disrupt the natural routes   
to infection, coupled with maternal passive immunity to protect newborns,     
will probably reduce occurrence of pertussis and may even eradicate the       
disease," concludes Manclark.

FDA scientists share their knowledge with other researchers by publishing     
their findings in the scientific literature and by hosting international      
conferences and workshops on pertussis. The research by Laboratory of         
Pertussis scientists has resulted in numerous patents, which, because they    
are held by the federal government, are available to vaccine manufacturers    
and others who are interested.

--R.D.W.