Merck to Present New Data Reinforcing Long-Term Efficacy of GARDASIL®9 and GARDASIL® at the EUROGIN International Multidisciplinary HPV Congress 2026

Data show long-term effectiveness of GARDASIL^®9 and GARDASIL^® 14 years and 18 years, respectively, following vaccination with 3 doses

Data on certain HPV-related oropharyngeal cancers reinforce the importance of vaccination for both females and males

Merck (NYSE:MRK), known as MSD outside of the United States and Canada, today announced it will present new clinical and real-world data reaffirming the long-term effectiveness of the company's 9-valent Human Papillomavirus (HPV) vaccine, GARDASIL^®9 (Human Papillomavirus 9-valent Vaccine, Recombinant) and its 4-valent HPV vaccine, GARDASIL^® (Human Papillomavirus 4-valent Vaccine, Recombinant) against certain HPV-related cancers and diseases at the EUROGIN International Multidisciplinary HPV Congress 2026 in Vienna, Austria, from March 18-21.

Data to be presented include results from studies evaluating the long-term effectiveness of HPV vaccination in women 16 to 26 years of age, showing vaccine effectiveness for at least 14 years following 3 doses of the 9-valent vaccine, and vaccine effectiveness up to 18 years after 3 doses of the quadrivalent vaccine against HPV 16/18-related high-grade cervical disease.

The company will share additional data on certain HPV-related oropharyngeal cancers, and adult- and juvenile-onset Recurrent Respiratory Papillomatosis (RRP) through studies done in the U.S., Denmark, Sweden, and the United Kingdom.

"Nearly two decades after the U.S. FDA approval of GARDASIL in June 2006, we are proud to present these data for GARDASIL 9 and GARDASIL that reinforce the long-term effectiveness and importance of HPV vaccination for females ages 9 to 45 years, beginning in adolescence," said Dr. Paula Annunziato, senior vice president, infectious diseases and vaccines, global clinical development, Merck Research Laboratories. "Additionally, data on certain HPV-related oropharyngeal cancers highlight the importance of HPV vaccination in helping to prevent these cancers, which impact both women and men."

Details on key abstracts for Merck:

GARDASIL, Merck's 4-valent HPV Vaccine, is not marketed in the United States.

Indication for GARDASIL and GARDASIL 9

GARDASIL 9 is a vaccine indicated in females 9 through 45 years of age. GARDASIL is a vaccine indicated in females 9 through 26 years of age. GARDASIL 9 is indicated for the prevention of cervical, vulvar, vaginal, anal, oropharyngeal and other head and neck cancers caused by human papillomavirus (HPV) Types 16, 18, 31, 33, 45, 52, and 58; and precancerous or dysplastic lesions caused by HPV Types 6, 11, 16, 18, 31, 33, 45, 52, and 58. GARDASIL is indicated for the prevention of cervical, vulvar, vaginal, and anal cancers caused by HPV Types 16 and 18, and precancerous or dysplastic lesions caused by HPV Types 6, 11, 16, and 18. Both are indicated for the prevention of genital warts caused by HPV Types 6 and 11.

GARDASIL 9 is indicated in males 9 through 45 years of age. GARDASIL is indicated in males 9 through 26 years of age. GARDASIL 9 is indicated for the prevention of anal, oropharyngeal and other head and neck cancers caused by HPV Types 16, 18, 31, 33, 45, 52, and 58; and precancerous or dysplastic lesions caused by HPV Types 6, 11, 16, 18, 31, 33, 45, 52, and 58. GARDASIL is indicated for the prevention of anal cancer caused by HPV Types 16 and 18, and precancerous or dysplastic lesions caused by HPV Types 6, 11, 16, and 18. Both are indicated for the prevention of genital warts caused by HPV Types 6 and 11.

The GARDASIL 9 oropharyngeal and head and neck cancer indication is approved under accelerated approval based on effectiveness in preventing HPV-related anogenital disease. Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.

GARDASIL 9 and GARDASIL do not eliminate the necessity for vaccine recipients to undergo screening for cervical, vulvar, vaginal, anal, oropharyngeal and other head and neck cancers as recommended by a health care provider.

GARDASIL 9 and GARDASIL have not been demonstrated to provide protection against diseases caused by:

• HPV types not covered by the vaccine
• HPV types to which a person has previously been exposed through sexual activity

Not all vulvar, vaginal, anal, oropharyngeal and other head and neck cancers are caused by HPV, and GARDASIL 9 and GARDASIL protect only against those vulvar, vaginal, anal, oropharyngeal and other head and neck cancers caused by HPV types contained in the vaccines.

GARDASIL 9 and GARDASIL are not a treatment for external genital lesions; cervical, vulvar, vaginal, anal, oropharyngeal and other head and neck cancers; or cervical intraepithelial neoplasia (CIN), vulvar intraepithelial neoplasia (VIN), vaginal intraepithelial neoplasia (VaIN), or anal intraepithelial neoplasia (AIN).

Vaccination with GARDASIL 9 or GARDASIL may not result in protection in all vaccine recipients.

Select Safety Information

GARDASIL 9 and GARDASIL are contraindicated in individuals with hypersensitivity, including severe allergic reactions to yeast, or after a previous dose of GARDASIL 9 or GARDASIL.

Because vaccinees may develop syncope, sometimes resulting in falling with injury, observation for 15 minutes after administration is recommended. Syncope, sometimes associated with tonic-clonic movements and other seizure-like activity, has been reported following HPV vaccination. When syncope is associated with tonic-clonic movements, the activity is usually transient and typically responds to restoring cerebral perfusion.

Safety and effectiveness of GARDASIL 9 and GARDASIL have not been established in pregnant women.

For GARDASIL 9, the most common (>10%) local and systemic adverse reactions in females were: injection-site pain, swelling, erythema, and headache. The most common (>10%) local and systemic reactions in males were injection-site pain, swelling, and erythema. For GARDASIL, the most common (>1.0%) adverse reactions were headache, fever, nausea, dizziness; and injection-site pain, swelling, erythema, pruritus, and bruising.

The duration of immunity of GARDASIL and a 2-dose schedule of GARDASIL 9 has not been established.

Dosage and Administration

Administer either GARDASIL 9 or GARDASIL intramuscularly in the deltoid or anterolateral area of the thigh.

For GARDASIL 9, a complete vaccination regimen consists of:

• For individuals 9 through 14 years of age, GARDASIL 9 can be administered using a 2- dose or 3-dose schedule. For the 2-dose schedule, the second dose should be administered 6–12 months after the first dose. If the second dose is administered less than 5 months after the first dose, a third dose should be given at least 4 months after the second dose. For the 3-dose schedule, GARDASIL 9 should be administered at 0, 2 months, and 6 months.
• For individuals 15 through 45 years of age, GARDASIL 9 is administered using a 3- dose schedule at 0, 2 months, and 6 months.

For GARDASIL, a complete vaccination regimen for individuals 9 through 26 years of age consists of 3 doses at the following schedule: 0, 2 months, 6 months.

About Merck

At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.merck.com and connect with us on X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn.

Forward-Looking Statement of Merck & Co., Inc., Rahway, N.J., USA

These statements are based upon the current beliefs and expectations of the company's management and are subject to significant risks and uncertainties. There can be no guarantees with respect to pipeline candidates that the candidates will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements.

Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; the company's ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of the company's patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions.

The company undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in the company's Annual Report on Form 10-K for the year ended December 31, 2025 and the company's other filings with the Securities and Exchange Commission (SEC) available at the SEC's Internet site (www.sec.gov).

Please see Prescribing Information for GARDASIL 9 (Human Papillomavirus 9-valent Vaccine, Recombinant) at https://www.merck.com/product/usa/pi_circulars/g/gardasil_9/gardasil_9_pi.pdf and Patient Information/Medication Guide for GARDASIL 9 at https://www.merck.com/product/usa/pi_circulars/g/gardasil_9/gardasil_9_ppi.pdf

Please see Prescribing Information for GARDASIL [Human Papillomavirus Quadrivalent (Types 6, 11, 16, and 18) Vaccine, Recombinant] at https://www.merck.com/product/usa/pi_circulars/g/gardasil/gardasil_pi.pdf and Patient Information/Medication Guide for GARDASIL at https://www.merck.com/product/usa/pi_circulars/g/gardasil/gardasil_ppi.pdf.

View source version on businesswire.com: https://www.businesswire.com/news/home/20260316267753/en/

Media Contacts:

Olivia Finucane

+44 7881 262476

[email protected]

Muchena Zigomo

+1 (267) 309-5591

[email protected]

Investor Contacts:

Peter Dannenbaum

+1 (732) 594-1579

[email protected]

Damini Chokshi

+1 (732) 594-1577

[email protected]