Background

The World Health Organization (WHO) Western Pacific Region, which is where the US-affiliated Pacific Islands (USAPI) are located, accounts for one quarter of all estimated cervical cancer cases. Cervical cancer is the 4th-most common cancer among women across the globe, part of the reason why human papillomavirus (HPV) vaccines are recommended for girls aged 11 to 12 years, as they prevent most cervical cancers, according to a new publication of the Centers for Disease Control and Prevention's (CDC) Morbidity and Mortality Weekly Report (MMWR).¹

The report is the first comprehensive one of trends in HPV vaccination coverage among adolescent girls since the vaccines were introduced in USAPI jurisdictions, to get a better understanding if coverage is on track to meet the 2030 WHO goal of ≥90% completion of the HPV vaccination series among girls by age 15 years.¹

The WHO strategy recommends that HPV vaccination be included in all national immunization programs, as the age-standardized rate of cervical cancer in the Marshall Islands is the highest in the world (74 per 100,000 women). The HPV vaccines, which have been licensed for use since 2006, are estimated to "have the potential to prevent approximately 75% of all cervical cancers," according to the MMWR authors.¹

Overall, the CDC states HPV vaccination is recommended for routine vaccination at age 11 or 12 years, though vaccination can be started at age 9 years. If not adequately vaccinated when younger, the Advisory Committee on Immunization Practices recommends vaccination for everyone through age 26 years.²

"Assessment of vaccination coverage among adolescent girls can help immunization programs monitor progress toward regional goals and identify populations and areas with low coverage, stated the investigators, who added, "These data can be used to guide evidence-based interventions, adapted to the local context, to improve vaccination coverage."¹

Study details and results

Predominantly provided through school-located vaccination programs, HPV vaccines were introduced to the USAPI during 2007 to 2016. The report highlighted HPV vaccination coverage among adolescent girls in 5 of the 6 USAPI jurisdictions from 2013 to 2023.¹

Individuals were included in the retrospective analysis of data from the immunization information systems (IISs) if they¹:

• Were adolescent girls aged 13–17 years as of January 1 of the assessment year
• Had an active patient status in the IIS through the end of the assessment year
• Had received any vaccine within the most recent 5 years

Completion of the HPV vaccination series was defined as receipt of 3 or more HPV vaccine doses, or receipt of 2 doses if the series was initiated at younger than 15 years of age, and if ≥5 months minus 4 days have elapsed between receipt of the first and second dose.¹

Vaccination series completion status varied by jurisdiction, as of December 2023, coverage with 1 or more dose among adolescent girls aged 13 to 17 years ranged from 58% in Palau to 97.2% in the Northern Mariana Islands. Series completion ranged from 43.3% in Palau to 91.8% in the Northern Mariana Islands, which as of 2023, is the only jurisdiction to have already met the WHO 2030 90% vaccination coverage goal.¹

Across all jurisdictions, from 2013 to 2023, coverage with ≥1 HPV vaccine dose increased by 35.2–72.8 percentage points. For series completion, coverage increased by 35.3-72.9 percentage points in the same time period. The percentage of girls who had received 1 or more dose and among those who completed the vaccination series increased each year from 2013 to 2023 in all jurisdictions except Palau.¹

In Palau, ≥1-dose coverage and HPV vaccination series completion coverage peaked in 2020 at 71.6% and 59.0%, respectively, and have since declined to 58.0% and 43.4%, respectively, in 2023, wrote the investigators.¹

Series completion coverage increased from 78% to 82.8% from 2022 to 2023 in American Samoa, which would meet the WHO 2030 goal by 2025 if vaccination trends continue to increase at the same rate.¹

Conclusion

As only 2 of the 5 USAPI have met or are on track to meet the WHO 2030 goal of ≥90% completion of the HPV vaccination series among girls by age 15 years, "Identifying and implementing evidence-based strategies to increase vaccine access and coverage would benefit jurisdictions with lagging coverage," stated the authors of the MMWR report.¹

"Vaccination coverage data can support development of their activities by providing performance indicators and data for modeling health outcomes related to HPV vaccination, promoting health equity, and attaining the WHO 2030 goal of 90% HPV vaccination series completion coverage," the authors concluded.¹

References:

1. Tippins A, Mutamba G, Boyd EM, Coy KC, Kriss JL. Human papillomavirus vaccination coverage among adolescent girls aged 13–17 years — US-affiliated pacific islands, 2013–2023. MMWR Morb Mortal Wkly Rep. 2024;73. doi:10.15585/mmwr.mm7333a2
2. HPV vaccination recommendations. CDC. May 22, 2023. Accessed August 23, 2024. https://www.cdc.gov/vaccines/vpd/hpv/hcp/recommendations.html