MBN, Monte Bubbles Network

 Merck & Co., Inc. today announced that the U.S. Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices (ACIP) unanimously voted to recommend that children 4 to 6 years of age receive a second dose of varicella vaccine for the prevention of chickenpox.  The Committee also recommended that children, adolescents and adults who received only one dose of varicella vaccine receive a second, "catch-up" dose, which can be accomplished through routine health-care visits and school- and college-entry requirements. 

Merck's VARIVAX® [varicella vaccine live (Oka/Merck)] and PROQUAD® [measles, mumps, rubella, varicella (Oka/Merck) virus vaccine live] are the only vaccines to protect against chickenpox in the United States.  VARIVAX is indicated for vaccination against varicella in individuals 12 months of age and older and PROQUAD is indicated for simultaneous vaccination against measles, mumps, rubella, and varicella in children 12 months to 12 years of age.  Chickenpox is highly contagious, easily spread, and sometimes can have serious complications - such as severe skin infections, pneumonia and encephalitis (swelling of the brain) that may result in hospitalization, or in rare cases, death. 

"While use of the one-dose regimen of the chickenpox vaccine has significantly reduced cases of chickenpox, we believe we can still do more," said Keith Reisinger, M.D., medical director, Primary Physicians Research.  "Because clinical data has shown that a two-dose regimen can potentially further lower the risk of infection, the ACIP's recommendation that children receive a second dose of the varicella vaccine makes it more likely that most American children can have even greater protection against this potentially serious disease."

Chickenpox Remains a Serious Health Concern
Prior to the introduction of VARIVAX in 1995, an estimated four million people¹ were infected with the chickenpox virus each year in the U.S., with 11,000 requiring hospitalization.² In 1996, the ACIP and the CDC added the varicella vaccine to the list of recommended childhood vaccinations.   PROQUAD was licensed in 2005 and provides an opportunity to administer simultaneous vaccination against measles, mumps, rubella and varicella, thus reducing the number of injections children receive and increasing varicella vaccination coverage to the national levels of coverage against measles, mumps and rubella, which is currently estimated to be 93 percent for children 19 to 35 months of age.  Vaccination coverage rates for varicella still vary widely across states, from 70 to 94 percent in children age 19 to 35 months; in 2004, an estimated 12.5 percent of children were not vaccinated.  Vaccination with VARIVAX or PROQUAD may not result in protection of all healthy, susceptible children, adolescents, and adults.

"Merck is proud that the use of our vaccines has contributed to the reduction in the incidence of chickenpox over the past 11 years," said Mark Feinberg, M.D., Ph.D., vice president of Policy, Public Health and Medical Affairs, Merck Vaccines.  "With widespread use of two doses of varicella vaccine, we hope to see fewer chickenpox outbreaks, especially in schools, and to we hope to see additional decreases in the number of children susceptible to the disease." 

The ACIP also voted to recommend that a second dose of varicella vaccine be included in the CDC Vaccines for Children (VFC) program.  Since 1994, the VFC program has provided vaccines to children who are Medicaid-eligible, uninsured, underinsured or Native American. 

Eligible children may receive recommended vaccines through VFC once the CDC contracts for the purchase of the vaccine.

Two Doses of Varicella Vaccine Lowered Risk of Developing Chickenpox in Clinical Studies 
In a randomized, controlled study in 2,216 children 12 months to 12 years of age that compared one dose of varicella vaccine (VARIVAX) to two doses over a 10-year observation period, the estimated vaccine efficacy was 94.4 percent for one dose and 98.3 percent for two doses.  During the 10-year observation period, this translates into a 3.3-fold lower risk of developing chickenpox more than 42 days after vaccination in children receiving two doses than in those who received one dose (2.2 percent vs. 7.5 percent, respectively).  In this trial, 99.6 percent of children 12 months to 12 years of age who received two doses of varicella vaccine (VARIVAX) three months apart achieved a protective level of antibodies six weeks after vaccination compared to 85.7 percent of those who received only one dose.   The duration of protection of VARIVAX is unknown.

Among 981 children who received two doses of VARIVAX three months apart and who were followed for 42 days after each dose, the two-dose regimen was generally well tolerated, with a safety profile generally comparable to that of the one-dose regimen.  The incidence of injection-site complaints (primarily redness and swelling) observed in the first four days following vaccination was slightly higher post second dose (overall incidence 25.4 percent) than post first dose (overall incidence 21.7 percent), whereas the incidence of systemic complaints in the 42-day follow up period was lower post second dose (66.3 percent) than post first dose (85.8 percent).

Since 1964, the ACIP, a panel of 15 immunization experts, has provided guidance and counsel to the U.S. Department of Health and Human Services and the CDC on the most effective means to prevent vaccine-preventable diseases.  The Committee writes recommendations regarding vaccine use among the pediatric population along with schedules regarding the appropriate periodicity, dosage, and contraindications applicable to the vaccines.  In addition to varicella and human papillomavirus as recommended by ACIP earlier today, the ACIP currently recommends vaccines for routine use in children to prevent diphtheria, Haemophilus influenza type b, hepatitis A, hepatitis B, influenza, measles, meningococcal disease, mumps, pertussis, pneumococcal disease, polio, rotavirus, rubella and tetanus.  Merck makes vaccines to help protect against nine of these 16 diseases.

Select Important Information about VARIVAX
VARIVAX is indicated for vaccination against varicella in individuals 12 months of age and older.  Children 12 months to 12 years of age should receive a 0.5-mL dose administered subcutaneously.  If a second 0.5-mL dose is administered, it should be given a minimum of three months later.  Adolescents and adults 13 years of age and older should receive a 0.5-mL dose administered subcutaneously at elected date and a second 0.5-mL dose 4 to 8 weeks later.

VARIVAX is contraindicated in certain individuals, including those with: a history of hypersensitivity to any component of the vaccine, including gelatin; a history of anaphylactoid reaction to neomycin; blood dyscrasias, leukemia, lymphomas of any type, or other malignant neoplasms affecting the bone marrow or lymphatic systems; an immunodeficient condition or receiving immunosuppressive therapy; active, untreated tuberculosis; active febrile illness; or those who are pregnant.

In children, adolescents, and adults monitored for up to 42 days, the adverse effects most frequently reported were as follows: fever, injection-site complaints, varicella-like rash (injection site), and varicella-like rash (generalized).

There are insufficient data to assess the rate of protection of VARIVAX against the complications of chickenpox (e.g. encephalitis, hepatitis, pneumonia) in children.

In a study in which children received two doses of VARIVAX three months apart, the two-dose regimen of VARIVAX was generally well tolerated, with a safety profile generally comparable to that of the one-dose regimen.  The duration of protection from varicella infection after vaccination with VARIVAX is unknown; however, long-term efficacy studies have demonstrated continued protection up to 10 years after vaccination.  Vaccination with VARIVAX may not result in protection of all healthy, susceptible children, adolescents, and adults.

Select Important Information about PROQUAD
PROQUAD is a combined attenuated live virus vaccine indicated for simultaneous vaccination against measles, mumps, rubella and chickenpox in children 12 months to 12 years of age.  No clinical data are available on the safety, immunogenicity and efficacy of PROQUAD in children less than 12 months of age.  PROQUAD may be used in children 12 months to 12 years of age if a second dose of measles, mumps and rubella vaccine is to be administered.

At least one month should elapse between a dose of a measles-containing vaccine, such as M-M-R® II (Measles, Mumps, and Rubella Virus Vaccine Live), and a dose of PROQUAD.  If for any reason a second dose of varicella-containing vaccine is required, at least three months should elapse between administration of the two doses.

PROQUAD should not be administered to certain individuals, including those with: a history of anaphylactic reactions to neomycin; a history of hypersensitivity to gelatin or any other component of the vaccine; blood dyscrasias, leukemia, lymphomas of any type, or other malignant neoplasms affecting the bone marrow or lymphatic system; an immunodeficient condition or receiving immunosuppressive therapy; active untreated tuberculosis; an active febrile illness (>101.3°F); or those who are pregnant.

In clinical trials with PROQUAD involving children 12 to 23 months of age, the most frequently reported injection-site adverse experiences (>1% of children) were pain/tenderness/soreness, erythema, swelling, ecchymosis, and rash. The most frequently reported systemic vaccine-related adverse experiences (>1% of children) were fever (>102°F), irritability, measles-like rash, varicella-like rash, rash (not otherwise specified), upper respiratory infection, viral exanthema, and diarrhea.

In a clinical trial involving 799 healthy 4- to 6- year-old-children who had received M-M-R II and VARIVAX at least one month prior to entry, 399 received PROQUAD and placebo, while 205 received M-M-R II and placebo concomitantly at separate injection sites.  Another 195 healthy children were administered M-M-R II and VARIVAX concomitantly at separate injection sites.  In the clinical trial described above, the rates of adverse experiences of injection-site reactions, nasopharyngitis, and cough, were generally similar among the three treatment groups.

Vaccination with PROQUAD may not offer 100 percent protection from measles, mumps, rubella and chickenpox (varicella) infection.

The duration of protection from measles, mumps, rubella, and varicella infection after vaccination with PROQUAD is unknown.

About Merck
Merck & Co., Inc. is a global research-driven pharmaceutical company dedicated to putting patients first. Established in 1891, Merck currently discovers, develops, manufactures and markets vaccines and medicines to address unmet medical needs. The Company devotes MMR® II is a registered trademark of Merck & Co., Inc., Whitehouse Station, N.J., U.S.A. 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, 2005, and in its periodic reports on Form 10-Q and Form 8-K, which the Company incorporates by reference.

PROQUAD® and VARIVAX® are registered trademarks of Merck & Co., Inc., Whitehouse Station, N.J., U.S.A.

MMR® II is a registered trademark of Merck & Co., Inc., Whitehouse Station, N.J., U.S.A.

¹ Centers for Disease Control and Prevention. Decline in annual incidence of varicella-selected states 1990-2001. Morbidity and Mortality Weekly Report. 2003;52(37);884-885, page 884.

² Galil K, Brown C, Lin F, Seward J. Hospitalizations for varicella in the Unites States, 1988 to 1999. Pediatric Infectious Disease Journal. 2002;21(10):931-935, page 932