Backgrounds:

HIV-infected patients are at increased risk of meningococcal infection. Conjugate meningococcal vaccines are recommended, but no studies have been conducted on the immunogenicity of MenACWY-TT in HIV-infected adolescents. Since HIV-infected adolescents may have impaired vaccine response, a two dose booster schedule might be needed.

Methods

Prospective observational study conducted in HIV-infected adolescents in Madrid with the administration of 2 doses of MenACWY-TT(2 months apart) and the assessment of serum bactericidal antibodies (SBA) assays using rabbit complement. Sera were scheduled to be assessed at baseline, one month and 10 months after second dose. A threshold of hSBA titres of>1:8 against C, W-135 and Y groups was considered protective. Vaccine response was defined as a postvaccination SBA titre of >1:32 in initially seronegative subjects (<1:8) and a 4-fold increase in titre from pre- to post-vaccination in initially seropositive subjects (>1:8). Most patients had been previously immunized with a primary series of MenC conjugate vaccine in the first year of life.

Results:

Twenty-eight HIV-infected adolescents were included (characteristics on figure 1). Overall, 7(25%), 7(25%) and 8(28.6%) patients had baseline protective antibodies against capsular groups C,W-135 and Y, respectively.

Most patients 21(75%) showed vaccine response to all vaccine serogroups. One month postvaccination, 20(71.4%) previously seronegative patients had hSBA titre >1:32 for each serogroup. Among initially seropositive patients, 4/7 had a 4-fold increase in hSBA titre against C, 4/7 against W-135 and 5/8 against Y group. After the second vaccine dose, the proportions achieving titres >1:1024 to groups C, W-135 and Y, were 9(32.1%), 21(75%) and 24(85.7%).

Conclusions/Learning Points:

HIV-infected adolescents with good immuno-virological status achieve appropriate antibody-mediated protection against serogroups C,W and Y after 2 booster doses of MenACWY-TT. Response at 12 months is under evaluation.