BACKGROUND	We compared the safety and immunogenicity of two combined diphtheria-tetanus-pertussis-inactivated poliovirus vaccines containing either acellular ( Pa , SmithKline Beecham Biologicals ) or whole cell ( Pw , Pasteur Merieux Connaught ) pertussis components , mixed with a Haemophilus influenzae type b polysaccharide polyribosylribitol phosphate-tetanus conjugate vaccine in an open , randomized study in healthy infants .\