To meet global cervical cancer elimination efforts, a wider range of affordable and accessible vaccines against human papillomavirus (HPV) are needed. We aimed to evaluate the immunogenicity and safety of a quadrivalent HPV vaccine (targeting HPV types 6, 11, 16, and 18), developed and manufactured by the Serum Institute of India (SIIPL). Here we report outcomes in the 9–14 years cohort.

This randomised, active-controlled, phase 2/3 trial was conducted at 12 tertiary care hospitals across India. Healthy participants aged 9–14 years or 15–26 years with no history of HPV vaccination were eligible for enrolment. Female participants were randomly assigned (1:1) with an interactive web response system, by use of a central computer-generated schedule and block randomisation (block sizes of 2, 4, 6, and 8), to receive the SIIPL quadrivalent HPV vaccine (Cervavac; SIIPL, Pune, India) or the comparator quadrivalent HPV vaccine (Gardasil; Merck Sharp & Dohme, Harleem, the Netherlands). Participants, investigators, laboratory technicians, and sponsors were masked to treatment allocation of female participants. Male participants were given the SIIPL quadrivalent HPV vaccine in an open-label manner. Study vaccines were administered intramuscularly with a two-dose schedule (at day 0 and 6 months) in the cohort aged 9–14 years, and with a three-dose schedule (at day 0, month 2, and month 6) in the cohort aged 15–26-years. Immunogenicity was assessed 30 days after the last dose by use of multiplexed ELISA. The primary outcome was the non-inferiority of immune response in terms of the geometric mean titre (GMT) of antibodies against HPV types 6, 11, 16, and 18 generated by the SIIPL quadrivalent HPV vaccine in girls and boys (aged 9–14 years) compared with the GMT generated by the comparator quadrivalent HPV vaccine in women aged 15–26 years at month 7 in the modified per-protocol population (ie, all participants who received all doses of study vaccines per assigned treatment group and had both day 0 and 1-month immunogenicity measurements after the last dose following protocol-defined window periods with no major protocol deviations). Non-inferiority was established if the lower bound of the 98·75% CI of the GMT ratio was 0·67 or higher. The co-primary outcome of occurrence of solicited adverse events (within 7 days of each dose) and unsolicited adverse events (up to 30 days after the last dose) was assessed in all participants who were enrolled and received at least one dose of study vaccine. The trial is registered with the Clinical Trials Registry – India (CTRI/2018/06/014601), and long-term follow-up is ongoing.

Between Sept 20, 2018, and Feb 9, 2021, 2341 individuals were screened, of whom 2307 eligible individuals were enrolled and vaccinated: 1107 (738 girls and 369 boys) in the cohort aged 9–14 years and 1200 (819 women and 381 men) in the cohort aged 15–26 years. No race or ethnicity data were collected. 350 girls and 349 boys in the SIIPL quadrivalent HPV vaccine group and 338 women in the comparator vaccine group were included in the modified per-protocol population for the primary endpoint analysis. The median follow-up for the analyses was 221 days (IQR 215–231) for girls and 222 days (217–230) for boys in the SIIPL quadrivalent HPV vaccine group, 223 days (216–232) for girls in the comparator vaccine group, and 222 days (216–230) for women in the comparator vaccine group. GMT ratios were non-inferior in girls and boys receiving the SIIPL quadrivalent HPV vaccine compared with women receiving the comparator vaccine: GMT ratios for girls were 1·97 …