What are the World Health Organization (WHO) recommendations on a single dose of the human papillomavirus (HPV) vaccine?

WHO Recommendations on Single Dose HPV Vaccination

The World Health Organization (WHO) currently recommends a single-dose schedule of HPV vaccine for individuals aged 9-20 years to prevent HPV infection. 1, 2

Current WHO Dosing Recommendations

• WHO has updated their dosing schedule recommendations to include a single-dose option for HPV vaccination for individuals aged 9-20 years 1, 2
• This recommendation is based on evidence showing that a single dose provides stable immune responses up to 5 years after vaccination 1
• For individuals initiating vaccination at age 21 or older, and for immunocompromised persons, a multi-dose schedule is still recommended 3

Evidence Supporting Single-Dose Efficacy

• A randomized controlled trial in Tanzania showed that single-dose seropositivity for HPV16 IgG antibodies at 60 months with either bivalent or nine-valent vaccine was more than 99% and non-inferior to two doses 1
• Although HPV16 and HPV18 antibody concentrations after one dose were lower than after two doses, they remained stable from month 12 to month 60 1
• There was no evidence of difference between one-dose and two-dose groups in HPV16 or HPV18 antibody avidity at 36 months for either vaccine 1

Implementation Status

• Several countries have already switched to or introduced HPV vaccination with a single-dose schedule following the WHO recommendation 2
• This approach may make equitable access to HPV vaccines more feasible, especially in resource-limited settings where the burden of cervical cancer is disproportionately high 4

Traditional Multi-Dose Recommendations

• Prior to the single-dose recommendation, the standard approach was:
  • A 2-dose schedule for individuals initiating vaccination before their 15th birthday, with doses at 0 and 6-12 months 5, 3
  • A 3-dose schedule for those initiating vaccination at age 15 years or older, with doses at 0,1-2, and 6 months 5, 6

Special Considerations

• Despite the single-dose recommendation, ongoing surveillance for potential waning immunity after a single dose is needed 1
• For adults aged 27-45 years, the Advisory Committee on Immunization Practices (ACIP) recommends shared clinical decision-making regarding HPV vaccination, as vaccine effectiveness might be lower among persons with risk factors for HPV infection or disease 6, 3
• A 3-dose schedule is still recommended for individuals with certain immunocompromising conditions, regardless of age at initiation 5

Clinical Implications

• The discovery that a single dose may be sufficient could significantly improve global vaccine coverage, particularly in regions with limited resources 4
• Single-dose vaccination could accelerate efforts to control cervical cancer worldwide 4
• Healthcare providers should emphasize the importance of HPV vaccination before potential exposure to HPV through sexual contact 7

Caveats and Pitfalls

• While single-dose vaccination shows promising results, some studies showed that HPV18 seropositivity at month 60 was 98% with bivalent vaccine and 93% with nine-valent vaccine, which did not meet non-inferiority criteria compared to two doses 1
• Cervical cancer screening recommendations have not changed for vaccinated individuals, as HPV vaccines do not protect against all cancer-causing HPV types 6
• The implementation of single-dose schedules should be accompanied by robust monitoring systems to evaluate long-term effectiveness 2, 4