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In view of the need for a cost effective Haemophilus influenzae type b (Hib) conjugate vaccine, a lyophilized vaccine as capsular polysaccharide (PRP) conjugated to tetanus toxoid (Sii HibPRO) was indigenously developed by Serum Institute of India Ltd., Pune (SIIL). From 2004-07, this new vaccine underwent a series of clinical studies before its licensure by National Regulatory Authority (NRA). This paper discusses the results obtained during the clinical development of this vaccine. On finding the vaccine to be safe in animal toxicity studies, a Phase I single dose study was carried out to assess the safety profile of Sii HibPRO in healthy adult male volunteers. Subsequently, in Phase III pre-licensure study, immunogenicity and safety of Sii HibPRO was assessed and compared with Hib tetanus conjugate vaccine (Act-HIB) of Aventis, France. Immunogenicity was evaluated based upon serum anti-PRP IgG antibody concentrations by ELISA at prevaccination and one month each after the second and third dose. Safety was evaluated by recording details of adverse events after each dose of the vaccine. Postvaccination after the third dose, there was 100% seroprotection (anti PRP IgG titre >or= 0.15 microg/ml) in both the groups. Long term protection (>or=1 microg/ml) was achieved in 95.2% and 98.06% infants in Sii HibPRO and Act-HIB groups, respectively. At 15 months, prior to booster dose, 30 children in each group were evaluated and all were found to be seroprotected. Post booster, all of them responded with a strong boost response. Safety of Sii HibPRO was re-established in the post marketing surveillance in which 2,739 doses were administered to 1,029 infants, in 23 cities across India.

An open, comparative study was conducted at two tertiary care hospitals in India to assess immunogenicity and reactogenicity following administration of the DTwP/HB combination vaccine (Q-Vac) alone and DTwP and HB (Genevac B) vaccines at separate sites. These vaccines manufactured by Serum Institute of India, Ltd. (SIIL), Pune were compared with DTwP/HB vaccine (Tritanrix HB) manufactured by GlaxoSmithKline (GSK) in infants aged 6-14 weeks. The sample size comprised 447 infants who received DTwP/HB vaccine (Group A-150, SIIL) or DTwP and HB (Group B-147, SIIL) vaccines at separate sites or DTPw/HB vaccine (Group C-150, GSK), in a dose of 0.5 ml intra-muscularly. Pre and postvaccination IgG antibodies were determined by ELISA. Postvaccination, in Group A seroprotection was 99.3%, 100%, 96% and 100% to Diphtheria, Tetanus, Pertussis and HBs components respectively. In Group B (n = 147) it was 98.6%, 100%, 95.9% and 99.3% and in Group C (n = 150), it was 96%, 99.3%, 93.3% and 98.6% to D, T, P and HBs component of the vaccine. Postvaccination, geometric mean titres for each component were comparable across three groups by analysis of variance (ANOVA). Adverse events observed were within the range quoted in literature and no Serious Adverse Event (SAE) was observed. Reactogenicity profile in all three groups was comparable. Q-Vac vaccine manufactured by SIIL was found to be safe and immunogenic. Hepatitis B (HB) component did not interfere with the immune response to DTwP components of the vaccine.