Merck & Co, Inc announced today that it has submitted a Biologics License Application for ROTATEQ® (rotavirus vaccine, live, oral, pentavalent) to the U.S. Food and Drug Administration (FDA). ROTATEQ is Merck\'s investigational vaccine to protect against rotavirus gastroenteritis. ROTATEQ is an oral, liquid vaccine that contains five human serotypes - G1, G2, G3, G4 and P1. These serotypes cause most rotavirus disease worldwide.

Merck submitted the application to the FDA on April 5 and also announced that it has plans to file for licensure of ROTATEQ in Australia, Canada, the EU and Mexico, as well as countries in Asia and Latin America in 2005. Within the next 60 days, the FDA will determine whether it will accept for review Merck\'s application as submitted.

About Rotavirus Gastroenteritis

Rotavirus causes approximately one-third of diarrhea-associated hospitalizations in developing countries and nearly half a million deaths worldwide every year in children under five. In the United States, rotavirus accounts for approximately 50,000 hospitalizations, 500,000 visits to primary care offices and 20-40 deaths annually. Although symptoms may 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. 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 affect incidence.

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 changes from season to season. Children gradually develop immunity against different strains of the virus after several infections.

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 http://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 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.

ROTATEQ® is a registered trademark of Merck & Co., Inc.

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