FDA Vaccines Advisory Committee Unanimously Agrees That Clinical Data from 70,000-Infant Phase III Trials Support the Efficacy and Safety of ROTATEQ®, Merck's Investigational Vaccine for Rotavirus Gastroenteritis

Business Wire, Dec 14, 2005

WHITEHOUSE STATION, N.J. -- Merck & Co., Inc. announced today that the U.S. Food and Drug Administration's (FDA) Vaccines and Related Biological Products Advisory Committee voted unanimously that the data from the Phase III clinical trials with 70,000 infants support the efficacy and safety of ROTATEQ(R) (rotavirus vaccine, live, oral, pentavalent), the Company's investigational vaccine developed to prevent rotavirus gastroenteritis. Rotavirus gastroenteritis is the most common cause of severe dehydrating diarrhea in infants and young children, causing an estimated 250,000 emergency department visits and 500,000 visits to physicians offices each year in the United States.

"Rotavirus is a common childhood disease that sends hundreds of thousands of children to the doctor's office every year in the United States alone," said Peter S. Kim, Ph.D., president, Merck Research Laboratories. "We are pleased that the Advisory Committee agreed that the data presented showed that ROTATEQ reduced the effects of this potentially serious disease. We look forward to working with the FDA on the next steps of the application review process."

The Advisory Committee also recommended that Merck continue to develop and conduct post-licensure studies to assess the safety and efficacy of ROTATEQ if it is approved for use. The Advisory Committee's recommendation was based on data presented from Phase III clinical trials including the Rotavirus Efficacy and Safety Trial (REST), one of the largest vaccine clinical trials ever conducted.

The committee's recommendation will be considered by the FDA in its review of the Biologics License Application (BLA) that Merck submitted for ROTATEQ on April 5, 2005. The FDA is not bound by the committee's recommendation but takes its advice into consideration when reviewing investigational vaccines seeking approval. Merck has also filed for licensure of ROTATEQ in more than 50 other countries worldwide.

About ROTATEQ

ROTATEQ is an investigational oral vaccine that targets the five strains of rotavirus - G1, G2, G3, G4 and P1 - that cause most rotavirus disease worldwide. ROTATEQ was studied in infants as a three-dose vaccine, given at four- to ten-week intervals with the first dose administered at age six to 12 weeks and compared to placebo.

About Rotavirus Gastroenteritis

Rotavirus causes approximately one-third of diarrhea-associated hospitalizations in developing countries and more than 500,000 deaths worldwide every year in children under five. In the United States, rotavirus accounts for an estimated 70,000 hospitalizations and 500,000 visits to primary care offices. Although symptoms vary, those typically associated with rotavirus gastroenteritis include vomiting, fever, abdominal pain and watery diarrhea which can persist for three to nine days. The severity of rotavirus gastroenteritis ranges from asymptomatic to dehydrating gastroenteritis that can be fatal. The incidence of rotavirus is similar in developed and developing countries, which suggests that differences in environment (e.g., clean water, hygiene or sanitation) do not prevent this disease.

During the first few years of life, a child typically has several rotavirus infections. The highest rates of gastroenteritis are generally in children under two years of age, who are also at the greatest risk for severe disease. Nearly all children will be infected with rotavirus by age five. There are several different serotypes of rotavirus and the prevalence of these serotypes varies by geographic region and can change from season to season. Children gradually develop immunity against different strains of the virus after several infections.

ROTATEQ is one of three Merck vaccines currently being evaluated by the FDA. The FDA and other regulatory agencies around the world are reviewing applications for ZOSTAVAX, Merck's investigational vaccine to prevent shingles and shingles-associated pain in adults, and GARDASIL, the Company's investigational HPV and cervical cancer vaccine.

About Merck

Merck & Co., Inc. is a global research-driven pharmaceutical company dedicated to putting patients first. Established in 1891, Merck discovers, develops, manufactures and markets vaccines and medicines in more than 20 therapeutic categories. The company devotes extensive efforts to increase access to medicines through far-reaching programs that not only donate Merck medicines but help deliver them to the people who need them. Merck also publishes unbiased health information as a not-for-profit service. For more information, visit www.merck.com.

Forward-Looking Statement

This press release contains "forward-looking statements" as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements are based on management's current expectations and involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements may include statements regarding product development, product potential or financial performance. No forward-looking statement can be guaranteed, and actual results may differ materially from those projected. Merck undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this press release should be evaluated together with the many uncertainties that affect Merck's business, particularly those mentioned in the cautionary statements in Item 1 of Merck's Form 10-K for the year ended Dec. 31, 2004, and in its periodic reports on Form 10-Q and Form 8-K, which the company incorporates by reference.