21.   But new vaccines could one day provide another way.

22.   But now health officials in Cuba say a new AIDS vaccine will be ready for use within two to five years.

23.   But some of the money also will be devoted to developing new vaccines and getting stalled products back on track.

24.   But the new vaccines will be made using more modern methods, and there will be slight differences between them.

25.   But the researchers hope they will soon be able to test new vaccines, drugs and diagnostic tools for smallpox.

26.   By contrast, he said, the new vaccine is developed from tissue cells grown in clean, modern conditions, where contamination is much less likely.

27.   Caldwell was principal investigator for clinical trials of the new vaccine, developed by SmithKline Beecham pharmaceuticals.

28.   Certiva is a combination diphtheria, tetanus, pertussis vaccine which contains a new safer vaccine component for pertussis, or whooping cough.

29.   Companies began developing the new acellular vaccines after several countries stopped using the whole cell vaccines due to side effects.