A randomized, active-controlled, multi-centric, phase-II clinical study to assess safety and immunogenicity of a fully liquid DTwP-HepB-IPV-Hib hexavalent vaccine (HEXASIIL®) in Indian toddlers

Combination vaccines are effective in simplifying complex vaccination schedules involving multiple vaccines. A fully liquid hexavalent diphtheria (D)-tetanus (T)-whole-cell pertussis (wP)- hepatitis B (HepB)-inactivated poliovirus (IPV)-Haemophilus influenzae b (Hib) vaccine (HEXASIIL®), manufactured by Serum Institute of India Pvt. Ltd. was tested for safety and immunogenicity following booster vaccination. This was a phase-II/III, open label, multicentric, controlled trial in toddlers (phase II) and infants (phase III) in India. This manuscript presents results of phase II. Healthy toddlers aged 12–24 months were randomized (1:1) to receive a 0.5 ml booster dose of HEXASIIL® or comparator Pentavac SD + Poliovac, intramuscularly and followed for 28 days for safety assessment. Blood samples were collected pre-vaccination and 28 days post-vaccination to assess immunogenicity. Descriptive summary statistics were provided for safety and immunogenecity analyses. A total of 223 subjects were randomized. One subject droped out prior to dosing, due to consent withdrawal. Thus, 222 subjects received study vaccine (110 HEXASIIL® and 112 comparator). Frequency of solicited adverse events was comparable between HEXASIIL® and comparator (85.5 % vs 90.2 %). Most local and systemic solicited AEs were mild to moderate in severity. All events resolved completely without any sequelae and none led to subject discontinuation. No vaccine related serious AE was reported. Post vaccination, seroprotection rates against tetanus, Hib and polio type 1 and 3 were 100 % in both the groups. Seroprotection rates for diphtheria (99.1 % vs 100 %) and polio type 2 (98.2 % vs 100 %) were observed in HEXASIIL® and comparator group, respectively. For Hepatitis B, seroprotection was >99 % in both groups. Seroconversion observed for Bordetella Pertussis (94.5 % vs 95.4 %) and Pertussis Toxin (77.1 % vs 87.2 %) in HEXASIIL® and comparator group, respectively. HEXASIIL® vaccine was found to be safe and immunogenic in toddlers and supported its further clinical development in infants. Clinical Trial Registration – CTRI/2019/11/022052. •Combination vaccines simplify vaccination schedules and improve compliance.•HEXASIIL® vaccine was compared to licensed DTwP-HepB-Hib + IPV vaccines.•HEXASIIL® had good safety and immunogenicity profile.•The data supported further evaluation of HEXASIIL® in infants.