16 Acellular pertussis vaccines, now available in Australia and licensed for all age groups, may be better tolerated than whole cell vaccines, but few data are available on their use in preterm infants. PRP-T given on a 2,4,12 month schedule also produced a reduced response in preterm infants after 2 doses, although no difference was seen after the third dose. After administration of OPV the virus is excreted in the stool for about 6 weeks. Because of the theoretical risk of transmission to other infants, the vaccine should not be given to preterm infants until they are discharged from hospital. It is also the vaccine of choice for infants who have a disease, or are receiving treatment, which lowers immunity.
Limited data are available on the use of polio vaccines in preterm infants.
14 Sick preterm infants given 2 doses of IPV showed a poor response to all 3 serotypes. A number of studies have examined the response of preterm infants to hepatitis B vaccine with conflicting results. Several studies have shown a lower seroconversion rate and reduced antibody response in preterm infants immunised at birth. An improved response was seen if immunisation was delayed until the infants reached a weight of 2kg, or if it was given at about 1 month of age. 25,26,27 Other studies have demonstrated a satisfactory antibody response in preterm infants.