NEW YORK (Reuters) -- Controversy surrounding the possibility of serious side effects from the pertussis vaccine has led to changes in immunization programs in some countries to halt routine vaccination against pertussis, or whooping cough. Researchers estimate that hundreds of thousands of children have suffered the effects of these policy changes by contracting pertussis, according to a report in The Lancet.
Complications such as pneumonia and severe neurological damage are common in children with pertussis, and treatment strategies remain largely ineffective. For these reasons, prevention of the childhood disease is "paramount," with immunization leading these efforts. Now that mass vaccination programs in many developed countries have caused dramatic drops in pertussis rates, people have started to wonder if the vaccine is doing more harm than good.
In countries such as Sweden, Japan, the UK, the Russian Federation, Ireland, Italy, the former West Germany and Australia, allegations that the vaccine itself may cause brain damage, sudden infant death syndrome (SIDS), infantile spasms, or Reye's syndrome have led to changes in national immunization policies.
Yet experts like Dr. E.J. Gangarosa of Emory University in Atlanta, Georgia, argue that such "side effects" are often unrelated to the vaccine, and those that are "...are so rare that they defy measurement." On the other hand, the complications of whooping cough are well-documented.
In a study reported in Saturday's issue of The Lancet, Gangarosa and colleagues examined the effects of anti-vaccination campaigns on pertussis rates in the countries listed above, as well as in Hungary, the former East Germany, Poland and the US, where vaccination programs were not disrupted.
The researchers found that anti-pertussis vaccination campaigns had a "dose-response" effect on each of the countries where vaccination policies were changed. For example, in Sweden and Hungary, which were at the extremes of these movements, cases of pertussis rose 10- to 100-fold. By contrast, vaccination rates in the US and Canada were almost untouched by the campaigns.
Many of the countries in which pertussis vaccination programs were halted as a result of anti-vaccination campaigns have since reinstated their vaccination programs, Gangarosa said in an interview. For example in the UK, after the vaccine program was disrupted, vaccine coverage dropped from 90% to as low as 30%. Within about 18 months an epidemic ensued, after which the country decided to reinstate its pertussis immunization program aggressively, bringing vaccination rates back up to 90% and higher.
"Cases among children deprived of vaccine may have exceeded hundreds of thousands, and disease-related clinical complications... may have numbered tens of thousands," Gangarosa and colleagues speculate. However, they point out that the anti-vaccine movements have also led to stricter surveillance of pertussis, research to develop better vaccines, and the development of pertussis injury-compensation programs -- all beneficial effects.
Gangarosa told Reuters that "...the whole-cell vaccine -- the one that has been used for many years -- is a good vaccine, one that has done a remarkable job of controlling pertussis." He said that there is a new acellular vaccine available, one with fewer side effects, but it is less effective and more expensive than the old vaccine, and simply may not be a practical choice for many countries. On the other hand, "...some countries, like the US, have already made the decision to adopt the new vaccine."
SOURCE: The Lancet (1998;351:356-361)
