With the availability of the nonavalent human papillomavirus vaccine (9vHPV), parents, vaccinees, and vaccinators will be faced with questions on how to complete an immunization course started with the bi- or quadrivalent vaccine and whether to revaccinate individuals who have completed a full immunization course with the bi- or quadrivalent vaccine.
To address the questions raised on an individual level, four scenarios are proposed based on the age at the start of vaccination (9 to 14 years of age versus 15 years and older, the cut-off for 2 or 3 doses schedule), the number of doses already received and the time interval between those doses. Such individual guidelines are based on the European Summary of Product Characteristics (SmPC), available scientific data, and take into consideration guidelines made already by recommending bodies as well as expert opinions.
As an example, the scenario for completing partially vaccinated girls, 9-14 years of age is shown (Table 1).
Table 1. Scenario sequential doses administration, for girls 9-14 years of age.
Month 0 | Month 6 | Month 12 | Expected protection* |
2vHPV | Incomplete | ||
2vHPV | 9vHPV | 2 types | |
2vHPV | 9vHPV | 9vHPV | 2 types and likely protection for the 7 extra types |
4vHPV | Incomplete | ||
4vHPV | 9vHPV | 4 types | |
4vHPV | 9vHPV | 9vHPV | 4 types and likely protection for the 5 extra types |
*: Expected according to currently available data and expert judgment; role of cross-protection is not taken into consideration
Although a single dose of vaccine may provide some protection[1], so far robust clinical data is lacking.
On an individual basis, the 9-valent vaccine can be used to complete an incomplete vaccination regimen or might be added to a previously completed schedule to extend protection. Finally, this position can also be applied to the vaccination of boys.
[1] Kreimer AR, Struyf F, Del Rosario-Raymundo MR, Hildesheim A, Skinner SR, Wacholder S, et al. Efficacy of fewer than three doses of an HPV-16/18 AS04-adjuvanted vaccine: combined analysis of data from the Costa Rica Vaccine and PATRICIA trials. Lancet Oncol. 2015;16:775-86.