Abstract
Earlier publication from the ongoing multi-centric study of the International Agency for Research on Cancer to evaluate less than three doses of the quadrivalent Human Papillomavirus (HPV) vaccine in India amongst unmarried girls demonstrated non-inferior total antibody titres, neutralizing antibody titres and antibody avidity in 2-dose recipients compared to 3-dose recipients at 15–18 years of age (Bhatla et al., 2018) [7].The number of participants recruited at 15–18 years of age was 1515 and 1795 in the 3-dose and the 2-dose groups respectively. At a median follow-up of 7 years, incident HPV 16/18 infections were detected in 1.6% women receiving two doses and 0.8% women receiving three doses at 15–18 years. Frequency of incident infection was 7.0% in the age- and site-matched unvaccinated women (N = 1484). No persistent infection from HPV 16 was observed in the 2- or 3-dose recipients and one (0.2%) persistent HPV 18 infection was documented, each in the 3-dose and 2-dose cohorts. Among the unvaccinated women, the frequency of HPV 16/18 persistent infection was 1.7%.The protection offered by two doses of quadrivalent HPV vaccine against incident and persistent infections in recipients at 15–18 years is comparable to that seen in 3-dose recipients at 15–18 years.
Highlights
The Strategic Advisory Group of Experts (SAGE) of the World Health Organization (WHO) recommended a 2-dose schedule of the Human Papillomavirus (HPV) vaccine for girls below 15 years of age in the year 2014 [1]
In our earlier publication based on the ongoing study from India we reported that the immunogenicity in 15–18 year old recipients of two doses of the quadrivalent HPV vaccine was non-inferior to that in the 15–18 years old recipients of three doses for all the vaccine targeted types [7]
The WHO guidance recommending two doses for young adolescents below 15 years of age was based on the outcomes of the immunological bridging studies that traditionally selected 9–14 years age group to be compared with the older women with a broad age range of 15–26 years; the efficacy of the three doses of the vaccine being proven in the later age group [3,10,11,12,13]
Summary
The Strategic Advisory Group of Experts (SAGE) of the World Health Organization (WHO) recommended a 2-dose schedule of the Human Papillomavirus (HPV) vaccine for girls below 15 years of age in the year 2014 [1]. Several immunological bridging studies and their systematic reviews conclusively demonstrated that the antibody response following two doses (administered at an interval of at least six months) of the HPV vaccine in the girls below 15 years of age was non-inferior to that in older women receiving standard three doses of the vaccine, the efficacy of three doses having been already established in the second group [3,4]. In our earlier publication based on the ongoing study from India we reported that the immunogenicity in 15–18 year old recipients of two doses of the quadrivalent HPV vaccine was non-inferior to that in the 15–18 years old recipients of three doses (standard of care) for all the vaccine targeted types [7]. In the present manuscript we report the comparative protection offered against incident and persistent HPV infections in recipients of two and three doses of the quadrivalent vaccine at 15–18 years of age
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