Serological Response to Antipneumococcal Vaccination and Impact on Streptococcus Pneumoniae Nasal Carriage in HIV Adults (PCV13HIV2011)

Serological Response to Antipneumococcal Vaccination and Impact on Streptococcus Pneumoniae Nasal Carriage in HIV Adults

Serological Response to Antipneumococcal Vaccination and Consequent Impact on Streptococcus Pneumoniae Nasal Carriage in HIV Positive Adults: a Prospective Study Using 13-valent Conjugate Vaccine

S. pneumoniae is frequently isolated from nasal swabs of healthy subjects, but it can also cause severe diseases (pneumonia, bacteraemia, meningitis and sepsis).HIV-infected subjects are more sensitive to invasive diseases and recurrent infection than the general population. Nasal carriage is the main pathogenetic feature for invasive disease: bacteraemia is more frequent in carriers, HIV+ patients are constantly colonized by the same pneumococcal strain and their nasopharyngeal isolates have features similar to subsequent invasive strains. A 23-valent polysaccharide vaccine (PPV23) has long been available and recommended in the HIV+ population as prophylaxis for invasive disease. Studies regarding efficacy of PPV23 in HIV+ are controversial and highlight that immune response induced by PPV23 in HIV+ is poor and an hyporesponsiveness to repeated polysaccaridic antigens stimulation can occur. Moreover, PPV23 seems not to affect pneumococcal carriage status and could lead to emergence of non-vaccine serotypes. The conjugation of pneumococcal capsular polysaccharides to carrier proteins results in an improved T-cell dependent immune response, characterized by increased antibody concentrations and induction of T and B memory cells, with a demonstrated higher efficacy in children. A heptavalent vaccine conjugated with diphtheria toxoid (PCV7) is approved in Europe since 2001 and is effective in reducing incidence of invasive disease by vaccine serotypes (4, 6B, 9V, 14, 18C, 19F, 23F), in both children and adults, due to effect of herd immunity. A PCV13 formulation has recently been developed, covering PCV7 serotypes plus 1, 3, 5, 6A, 7F and 19A. PCV13 revealed the same safety profile as PCV7 in pediatric patients, that are the main target of conjugate vaccines licensure. Some trials showed a better antibody response in terms of quantity and quality in HIV + adults by using PCV7 as compared to PPV23. However these data were not unequivocally confirmed in further studies on the use of PCV7 alone or in combination with PPV23. The first trials of PCV13 use in adults showed the same or even better response compared to PPV23, with a safety and tolerability similar to PCV7. PCV13 in HIV+ adults is a promising candidate prophylactic measure for pneumococcal infections. The purpose of this study is to evaluate serological response and prevalence of nasopharyngeal colonization by S. pneumoniae in HIV+ non-hospitalized adults, following vaccination with 2 doses of PCV13.

HIV, Streptococcus pneumoniae, 13-valent conjugate pneumococcal vaccine, Vaccine, Immunological Response, Pneumococcal Carriage

Pneumococcal polysaccharide conjugate vaccine(13-valent adsorbed) conjugated to CRM197 carrier protein and adsorbed on aluminum phosphate (0.125 mg of aluminum). Pharmaceutical form: suspension for injection. Dosage: 0.5 ml, containing 2.2 g of polysaccharide for serotypes 1, 3, 4, 5, 6A, 7F, 9V, 14, 18C, 19A, 19F, 23F, and 4.4 micrograms for serotype 6B. Prevenar 13 is administered in two doses,each of 0.5 ml, with an interval of 2 months, injected intramuscularly in the deltoid muscle of the arm.

Measure of serological response after 2 doses of PCV13 vaccine (booster dose after 8 weeks) in HIV+ adults.

to determine the rate of nasopharyngeal colonization by different pneumococcal serotypes in HIV-positive adults, in relation to baseline antibody titers at T0

Molecular typing combining PFGE (Pulsed Field Gel Electrophoresis), MLST (MultiLocus Sequence Typing) and PCR analysis of bacterial isolates.

Inclusion Criteria: > 18 years old obtained informed consent outpatient CD4 ≥200 cells/µl in the last two evaluations before T0 Exclusion Criteria: > 65 years old presence of acute infectious disease antibiotic therapy (ongoing or in the previous <= 7 days) previous PPV23 or PCV7 vaccination Pregnancy Current immunomodulatory therapy Immunosuppression not HIV related

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