Long-term HPV vaccine efficacy: 10-year study reveals protection in youth

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A decade-long study confirms significant protection against human papillomavirus remains in patients vaccinated up to age 20, reinforcing the World Health Organization's single-dose vaccination recommendation for adolescents.

Long-term HPV vaccine efficacy: 10-year study reveals protection in youth | Image Credit: © Chinnapong - © Chinnapong - stock.adobe.com.

Long-term HPV vaccine efficacy: 10-year study reveals protection in youth | Image Credit: © Chinnapong - © Chinnapong - stock.adobe.com.

Protection against human papillomavirus (HPV) 10 years following vaccination is present in patients aged up to 20 years at the time of vaccination, according to a recent study published in Human Vaccines & Immunotherapeutics.

Takeaways

  1. The study found that 10 years after receiving a single dose of the HPV vaccine, significant antibody responses against HPV types 16 and 18 were present in both younger (aged 10-14 years) and older (aged 15-20 years) age groups.
  2. While the antibody levels in those who received a single dose were lower than those who received 2 or 3 doses, they were still deemed significant, especially for the younger age group.
  3. The findings support the World Health Organization's recommendation of a single-dose HPV vaccination for individuals up to 20 years old. This approach may help in reaching a larger portion of the adolescent female population.
  4. There was a noted difference in antibody levels based on the age at which the vaccine was administered. Individuals vaccinated at a younger age (10-14 years) had higher antibody levels compared to those vaccinated at an older age (15-20 years).
  5. The study emphasized the importance of monitoring the long-term effectiveness of HPV vaccinations, especially with the extension of the recommended age range and the use of single-dose regimens.

In 2022, the World Health Organization (WHO) recommended patients aged 9 to 20 years receive an off-label, single dose HPV vaccine to significantly reduce lifetime cervical cancer risk. With the upper age for the vaccine extended to 20 years, it is vital to understand the durability of immune response following a single dose.

Research has indicated antibody titers after 2 bivalent vaccine doses in female individuals aged 18 to 25 years is approximately half of those in female individuals aged 10 to 17 years. This has led to a question of whether protective immune responses would last for a women’s lifetime following a single dose vaccination after 15 years of age.

Investigators conducted a study to determine long-term immunogenicity outcomes in younger and older patients at 10-years postvaccination. The study included longitudinal follow-up of participants receiving 3 doses, 2 doses, or 1 dose of HPV vaccination.

There were 2 groups of participants receiving 2 doses, a 2-dose group receiving doses at days 1 and 180 or greater, and a 2-dose default group receiving doses at days 1 and 60. There were 4,348 participants in the 3-dose group, 4,979 in the 2-dose, 3,452 in the 2-dose default, and 4,950 in the 1-dose. A comparison group consisted of 1,484 unvaccinated married women.

Follow-up was expected to continue until at least 2016. Blood samples were obtained at 10 years post-vaccination, while cervical samples were obtained each year for 4 consecutive years. A Luminex assay was used to evaluate cervical samples.

A blood sample collected at day 1 was reported in all groups, month 2 in the 2-dose and 3-dose groups only, months 12 and 24 in the 2-dose default and 1-dose groups only, and months 18, 26, 48, and 60 in all groups. In the 1-dose cohort, a blood sample at 10 years was collected in patients who had a baseline and 12-month sample collected.

Samples were evaluated for HPV 16 and 18 binding antibodies, with a parallel line value obtained to measure the number of antibodies present. A high throughput pseudovirion-based neutralization assay was also used to measure neutralizing antibodies against the HPV-L1 protein of HPV 16 and 18.

Of participants, over 60% were vaccinated when aged 10 to 14 years. Being aged 26 years or older at serology sample collection was reported by 32.6% of unvaccinated patients, 24.7% of 1-dose recipients, 31.1% 2-dose recipients, and 30.5% 3-dose recipients. Being married was reported in 100%, 71%, 61.1%, and 69.5%, respectively.

Detectable binding antibody titers against HPV types 16 and 18 were found in a significant proportion of 1-dose recipients in both age groups 10 years following vaccination. For HPV 16, the rates were 97.7% in the younger group and 92.3% in the older group. For HPV 18, these rates were 98.2% and 94.2%, respectively.

A 2.1-fold increase in the HPV 16 geometric mean titers (GMT) for binding antibodies was observed in patients vaccinated when aged 10 to 14 years compared to a 1.9-fold increase in those aged 15 to 18 years at 10 years after vaccination. An 11% reduction in HPV 15 GMT was observed in 1-dose recipients aged 15 to 18 years compared to those aged 10 to 14 years.

Similar patterns were observed for binding antibody GMT kinetics against HPV types 18, with a 3.7-fold increase in a 10-year GMT against HPV 18 observed among 1-dose recipients aged 10 to 14 years compared to a 3.1-fold increase in those aged 15 to 18 years. For both HPV types 16 and 18, 1-dose recipients had significantly lower mean GMTs compared to matched 2-dose and 3-dose recipients.

These results supported the WHO’s recommendation to receive a single dose vaccination when aged up to 20 years. Investigators concluded a single dose vaccine regiment may reach a greater proportion of the adolescent female population.

Reference

Bhatla N, Muwonge R, Malvi SG, et al. Impact of age at vaccination and cervical HPV infection status on binding and neutralizing antibody titers at 10 years after receiving single or higher doses of quadrivalent HPV vaccine. Human Vaccines & Immunotherapeutics. 2023;19(3). doi:10.1080/21645515.2023.2289242

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