Ans. b (Ref. OP Ghai 6th/pg.l94; Nelson paeds 17th /pg.908)PERTUSSISPreventionUniversal immunization of children <7 yr of age with pertussis vaccine, beginning in infancy, is central to the control ofpertussis. Current goals of immunization are protection of the individual from a significant coughing illness and controlof endemic and epidemic disease.ACELLULAR VACCINE# Multiple diphtheria and tetanus toxoids combined with acellular pertussis (DTaP) vaccines currently are preferred over those containing whole-cell pertussis (DTP) vaccines because of fewer adverse reactions.# Recommendations for use of DTaP are similar to recommendations for use of DTP, which continues to be given to infants and children in many other countries. Acellular pertussis vaccines all contain inactivated PT and may contain one or more other bacterial components (FHA, Pn, Fim 2 and 3).# Mild local and systemic adverse events as well as more serious events occur significantly less frequently among infants who receive DTaP compared with DTP vaccine.# DTaP containing vaccines can be administered simultaneously with any other vaccines used in standard schedules for children. Combination of vaccines that include DTaP in place of DTP can affect immunogenicity of products. Local reactions increase in rate and severity with successive doses of DTaP.# The same special considerations, precautions, contraindications, and reporting requirements for serious adverse events that exist for DTP vaccination apply to DTaP as well. Acellular pertussis vaccines are now licensed for use only among children through 6 yr of age.# Live virus vaccines should be avoided in immunocompromised patients. For patients without chronic GVHD, diphtheria and tetanus toxoids, acellular pertussis (in children <7 yr of age), inactivated polio, hepatitis B, Haemophilus influenzae type b, and Streptococcus pneumoniae immunizations may be given 12 mo after transplant, and measles- mumps-rubella immunizations after 24 mo. Influenza vaccines should be given every fall.# Currently available combinations are PRP-OMP combined with hepatitis B vaccine (Comvax) and a DtaP vaccine that can be combined with PRP-T for the fourth dose only.