Vaccine effectiveness is not
assured, however. Several BMS-907351 supplier studies have evaluated the tetanus vaccine responsiveness of children and adolescents on HAART. Those who are immunosuppressed when starting HAART have reduced capacity to mount protective responses to toxoid antigens, especially during the first year on HAART . Achieving viral suppression may have limited effect on restoring memory responses to tetanus toxoid, and on-HAART antibody responses are reduced in magnitude and durability [31, 37]. Tetanus-specific lymphocyte proliferation and antibody responses seem to be suppressed in the longer term, but this is possibly independent of the timing of vaccination  or HAART initiation . One study determined that anti-tetanus antibody titres declined from 27 times the baseline level to
3 times baseline within 32 weeks in HIV-infected children, whereas HIV-uninfected children used as historical controls achieved higher peak responses (180 times baseline), which were then sustained for 12 months post-vaccination (29 times baseline) . Another small study of pre- and post-tetanus booster responses in complete versus incomplete HAART responders showed modest cellular selleck chemicals llc and humoral responses in both groups, with poor durability , the antibody titres decaying rapidly within 1 year. So, despite numerical reconstitution over the first year on HAART, reimmunization rather than a single booster may be necessary to achieve durable protective anti-tetanus titres. Diphtheria is a weaker antigen than tetanus, and immunity wanes more rapidly in healthy children. In one study of children on HAART , 40–65% achieved protective vaccine-induced diphtheria antibodies, with some correlation with the degree of viral suppression achieved. Monitoring both tetanus- and diphtheria-specific titres can guide the need for reinforcing doses of vaccine. HIV-infected children should receive booster tetanus
vaccination (as a combined tetanus and diphtheria vaccine) much at least 10-yearly and antibody titres should be measured 5-yearly to guide additional boosting requirements. Given their favourable safety profile, acellular pertussis vaccines rather than whole-cell preparations are recommended for both the primary course in infancy and reinforcing doses. Studies on pertussis vaccine responsiveness are hampered by a lack of standardized functional assays and clinically relevant correlates of protection. Available data on HIV-positive children indicate that low CD4 cell count is associated with poor responsiveness in those not receiving HAART , while treated children mounted better responses to a reinforcing dose if their previous antibody titres were high, and if the degrees of CD4 recovery and viral suppression were greater.