Sir, - Kathryn Holmquist's otherwise excellent article (September 30th) on the new whooping cough vaccine included some misleading information on the level of protection conferred with "current vaccines". Most clinicians and scientists working in the field agree that the efficacy of the pertussis (whooping cough) component of the current 3 in 1 vaccine used in this country and in many other European countries is around 90 and 95 percent.

The figure of 36 per cent protection quoted in the article refers to an inferior, old type North American vaccine recently tested, in a comparison with the new vaccines (84-85 efficacy), in clinical trials in Italy and Sweden sponsored by the US National Institute of Allergy and Infectious Diseases.

The new vaccines, called a cellular vaccines, are composed of highly purified components of the bacteria, whereas the traditional vaccines, called whole cell vaccines, are composed of killed whole bacteria. While they may not be as fully efficacious as the old, because of their simplicity and refinement the new vaccines are less likely to be accompanied by mild to severe side effects sometimes associated with their predecessors.

Nevertheless, it still remains that the benefits of either vaccine still outweigh any risks; whooping cough is a very severe disease, which can be accompanied by serious complications. Poor public acceptance of the vaccine and reduced coverage can result in a high level of morbidity from the infection in the population as a whole.

At least 16 European countries have licensed the new vaccine, and many already have introduced it into their routine childhood immunisation programme. I look forward to a decision by the Department of Health on the introduction of a safer, new generation vaccine that is the culmination of 10-15 years' research and development by vaccine manufacturers and enthusiastic academic scientists alike. - Yours, etc.,

Infection and Immunity Group,

Department of Biology.

St. Patrick's College,