HPV16/18 Antibody Responses After a Single Dose of Nonavalent HPV Vaccine

Efficacy and immunogenicity of a single dose of human papillomavirus vaccine compared to multidose vaccination regimens or no vaccination: An updated systematic review of evidence from clinical trials

Objectives

This study systematically reviewed the published literature from clinical trials on the efficacy and immunogenicity of single-dose HPV vaccination compared to multidose schedules or no HPV vaccination.

Methods

Four databases were searched for relevant articles published from Jan-1999 to Feb-2023. Articles were assessed for eligibility for inclusion using pre-defined criteria. Relevant data were extracted from eligible articles and a descriptive quality assessment was performed for each study. A narrative data synthesis was conducted, examining HPV infection, other clinical outcomes and immunogenicity responses by dose schedule.

Results

Fifteen articles reporting data from six studies (all in healthy young females) were included. One article was included from each of three studies that prospectively randomised participants to receive a single HPV vaccine dose versus one or more comparator schedule(s). The other 12 articles reported data from three studies that randomised participants to receive multidose HPV vaccine (or control vaccine) schedules; in those studies, some participants failed to complete their allocated schedule, and evaluations were conducted to compare participants who actually received one, two or three doses. Across all efficacy studies, the incidence or prevalence of HPV16/18 infection was very low among HPV-vaccinated participants, regardless of the number of doses received; with no evidence for a difference between dose groups. In immunogenicity studies, HPV16/18 antibody seropositivity rates were high among all HPV-vaccinated participants. Antibody levels were significantly lower with one dose compared to two or three doses, but levels with one dose were stable and sustained to 11 years post-vaccination.

Conclusions

Results from this review support recent World Health Organization recommendations allowing either one- or two-dose HPV vaccination in healthy young females. Longer-term efficacy and immunogenicity data from ongoing studies are awaited. Randomised trials of single-dose HPV-vaccination are urgently needed in other populations, e.g. boys, older females and people with HIV.

Immunogenicity of 2-Dose HPV Vaccine Series for Postpartum Women: An Open-Label, Nonrandomized, Noninferiority Trial

Importance

Postpartum human papillomavirus (HPV) vaccination is a promising strategy to increase HPV vaccination uptake in the US, particularly for reaching vaccine-naive women and those who lack health insurance beyond the pregnancy period. However, completion of the 3-dose vaccine regimen is challenging.

Objective

To evaluate the immunogenicity of a 2-dose postpartum HPV vaccination regimen (0 and 6 months) and assess whether it is noninferior to a 3-dose postpartum HPV vaccination regimen (0, 1-2, and 6 months) administered to historical controls.

Design, Setting, and Participants

A noninferiority, open-label, nonrandomized immunogenicity trial was conducted from August 4, 2020, to June 23, 2022, of postpartum patients aged 15 to 45 years who delivered at 2 hospitals in Baltimore, Maryland. Historical controls were adolescents and young women aged 16 to 26 years.

Intervention

Two doses of the nonavalent HPV vaccine administered 6 months apart.

Main Outcomes and Measures

The primary outcome was noninferiority (90% CI, lower bound >0.67) of the geometric mean titer (GMT) ratio for HPV-16 among postpartum women compared with historical controls. Secondary outcomes were noninferiority of GMT ratios for the other 8 HPV types and percentage seroconversion for each HPV type. As a noninferiority trial, the primary analysis used the per-protocol analysis.

Results

Of 225 enrolled participants, the mean (SD) age at baseline was 29.9 (6.8) years, and 171 (76.0%) were HPV-16 seronegative at baseline. Of these 171 participants, 129 (75.4%) received a second vaccine dose and completed the subsequent 4-week serologic measurements. Relative to historical controls, the HPV-16 GMT ratio was 2.29 (90% CI, 2.03-2.58). At month 7, HPV-16 GMT was higher after the 2-dose regimen (7213.1 mMU/mL [90% CI, 6245.0-8331.4 mMU/mL]) than among historic controls after the 3-dose regimen (3154.0 mMU/mL [90% CI, 2860.2-3478.0 mMU/mL]). Similarly, the lower bound of the 90% CI of the GMT ratio was above 1 for the 8 HPV types 6, 11, 18, 31, 33, 45, 52, and 58. A total of 118 of 134 women (88.1%) seroconverted for HPV-16 after the first dose; 4 weeks after the second dose, the seroconversion rate was 99% or greater for all HPV types.

Conclusions and Relevance

This study suggests that immunogenicity of a 2-dose HPV vaccination regimen given 6 months apart among postpartum women was noninferior to a 3-dose regimen among young historical controls. Most women seroconverted after the first dose of the 2-dose regimen. These results demonstrate that postpartum vaccination using a reduced schedule may be a promising strategy to increase HPV vaccine series completion.

Trial Registration

ClinicalTrials.gov Identifier: NCT04274153.