Merck issued a statement on May 23, 2025, defending its current dosing recommendations for GARDASIL 9 (Human Papillomavirus 9-valent Vaccine, Recombinant) amid ongoing discussions about potential single-dose regimens. The pharmaceutical giant emphasized that existing 2- and 3-dose schedules should remain the standard until regulatory agencies approve alternative approaches based on sufficient clinical evidence.
FDA Sets High Bar for Single-Dose Approval
The company revealed that the FDA has established stringent requirements for any potential single-dose regimen approval. During pre-clinical trial discussions, the agency specified three critical evidence standards: comparable effectiveness data between single-dose and approved three-dose regimens, demonstration that single-dose efficacy is not reduced for HPV disease endpoints beyond cervical persistent infection, and efficacy data in men, where no single-dose data currently exists.
"The FDA was clear about the high standard of evidence that would be required for the licensure of single dose regimens," Merck stated, highlighting the regulatory complexity surrounding dosing modifications for established vaccines.
Current Approved Regimens Show Established Efficacy
GARDASIL 9 is currently approved for individuals aged 9-45 years for prevention of cervical, vulvar, vaginal, anal, oropharyngeal and other head and neck cancers caused by HPV types 16, 18, 31, 33, 45, 52, and 58. The vaccine also prevents precancerous lesions and genital warts caused by various HPV types.
The approved dosing schedule varies by age: individuals 9-14 years can receive either a 2-dose schedule (with the second dose 6-12 months after the first) or a 3-dose schedule, while those 15-45 years receive a 3-dose regimen at 0, 2, and 6 months. These regimens were evaluated in large clinical studies that met regulatory standards and have accumulated over 10 years of real-world experience since GARDASIL 9's 2014 approval.
Manufacturing Investment Supports Global Access
Merck has made substantial investments to ensure adequate global vaccine supply, committing over $2 billion to expand manufacturing capacity. This investment enabled the company to nearly double HPV vaccine supply from 2017-2020, then double it again between 2020-2024 to address increasing global demand.
The company currently supplies HPV vaccines to over 150 National Immunization Programs worldwide and continues supporting program expansions. Merck expects to maintain sufficient supply to meet anticipated demand while continuing capacity expansion efforts.
Safety Profile and Contraindications
The most common adverse reactions for GARDASIL 9 include injection-site pain, swelling, and erythema, along with headache in females. The vaccine is contraindicated in individuals with hypersensitivity to yeast or previous allergic reactions to GARDASIL vaccines. Healthcare providers are advised to observe patients for 15 minutes post-administration due to potential syncope.
The oropharyngeal and head and neck cancer indication operates under accelerated approval based on effectiveness in preventing HPV-related anogenital disease, with continued approval contingent upon confirmatory trial results that are currently ongoing.
