Merck,  known as MSD outside the United States and Canada, announced that the US Food and Drug Administration (FDA) has approved an expanded age indication for Zostavax (Zoster Vaccine Live) for the prevention of herpes zoster, commonly known as shingles, in adults 50 years of age and older. In a large clinical study, Zostavax significantly reduced the risk of developing shingles by nearly 70 per cent in adults ages 50 to 59, compared with placebo. Zostavax is the only shingles vaccine licensed for use in the US.

According to the US Centers for Disease Control and Prevention (CDC), in the US approximately 1 in 3 people will experience shingles in their lifetime and nearly one million cases of shingles occur each year. The incidence and severity of shingles increase with age. Once a person has had chickenpox the varicella-zoster virus (VZV) stays inside the body and can resurface later as shingles.

“This expanded indication is important for the health of people who are 50 and older because nearly everyone in that age group is at risk for developing shingles," said Jeffrey Silber, M.D., vice president, Merck Research Laboratories. “Zostavax can help to prevent this disease that can be painful and potentially debilitating for some people."

Zostavax is not indicated for the treatment of shingles or postherpetic neuralgia (PHN) or for the prevention of chickenpox. Zostavax is contraindicated for individuals who are allergic to any of its ingredients, including gelatin or neomycin, have a weakened immune system, take high doses of steroids, or are pregnant or plan to become pregnant. Vaccination with Zostavax may not result in protection of all vaccine recipients.

"Merck is investing more than $1 billion to enhance manufacturing so that as many people as possible may have access to Zostavax and our other varicella-containing vaccines," said Julie L. Gerberding, M.D., president, Merck Vaccines. "Merck remains committed to this important vaccine and to our customers who continue to support Zostavax and the critical role of adult vaccination in public health."

Customers can order Zostavax, but the product is currently on backorder. Merck will continue to release doses of Zostavax as supply becomes available, but as inventory is building, back orders will still occur.

The CDC currently recommends a single dose of Zostavax for all appropriate people 60 years of age and older, regardless of whether they have had a prior case of shingles, noting that persons with chronic medical conditions may be vaccinated unless their condition constitutes a contraindication.

Following FDA approval the next step is a vote by the CDC’s Advisory Committee on Immunization Practices (ACIP) on whether to recommend administration of Zostavax for use in people ages 50 to 59. Merck anticipates that the ACIP will vote on use of Zostavax in this population later this year. Some managed care companies may decide to provide reimbursement for Zostavax for adults ages 50 to 59 prior to the ACIP's vote; however, many insurance companies typically await the ACIP's vote before making a coverage determination.

Based on historical coverage information, Merck estimates that over 90 per cent of people 60 and older in the U.S. who have private health insurance are in plans that have approved reimbursement of Zostavax, and Medicare Part D plans covering over 90 percent of Part D enrollees in the US have included Zostavax on formulary. Whether a patient has coverage, and the amount of reimbursement, depends on the patient's benefit design, including any applicable co-pays, coverage limitations, co-insurance and/or deductibles and the reimbursement rate adopted by each plan. Zostavax is also a covered medical benefit for people 60 and older under the U.S. Veterans Health Administration and TRICARE, the health plan for the US Department of Defense Military Health System.

In Merck's Zostavax Efficacy and Safety Trial (ZEST), a randomized, double-blind, placebo-controlled study in adults who were 50 to 59 years of age at the time of vaccination, 11,184 volunteers received  Zostavax and 11,212 received placebo. Study participants were monitored for the development of shingles for a median of 1.3 years (range 0 to 2 years) after receiving vaccination. Participants also were followed for adverse events (AEs) for 42 days postvaccination and for serious adverse events (SAEs) through six months postvaccination.

In this study, 30 cases of shingles occurred in the vaccine group versus 99 cases of shingles in the placebo group: efficacy of the vaccine was 69.8 percent (95 percent Confidence Interval [CI]: 54.1 per
cent, 80.6 per cent), which met the study’s pre-specified criterion for success. Varicella-zoster virus antibody levels (Geometric Mean Titers, GMT), as measured by glycoprotein enzyme-linked immunosorbent assay (gpELISA) six weeks after vaccination, were increased 2.3-fold (95 per cent CI: 2.2 per cent, 2.4 per cent) in the group of subjects who received Zostavax compared to subjects who received placebo, meeting the pre-specified success criterion for this endpoint.

There was an overall higher incidence of AEs in the vaccine group versus the placebo group; this difference was primarily due to different rates of injection-site AEs (63.6 percent for vaccine vs. 14.0 per cent for placebo). The overall incidence of systemic adverse experiences reported within 42 days of vaccination was higher for Zostavax than for placebo (35.4 per cent for vaccine vs. 33.5 per cent for placebo); however, no significant differences were observed between the two study groups for any individual systemic AEs with the exception of pain in the extremity and headache. Serious adverse events (SAE) occurred at a similar rate in subjects vaccinated with Zostavax or placebo within 42 days of vaccination (0.6 per cent for vaccine vs. 0.5 per cent for placebo) and 182 days of vaccination (2.1 per cent  for vaccine vs. 1.9 per cent for placebo). An anaphylactic reaction was reported for one study participant who received Zostavax.

Zostavax is a live attenuated virus vaccine indicated for prevention of herpes zoster (shingles) in individuals 50 years of age and older. Zostavax is not indicated for the treatment of zoster or postherpetic neuralgia (PHN). Zostavax should not be used for prevention of primary varicella infection (Chickenpox).

Today's Merck is a global healthcare leader working to help the world be well. Merck is known as MSD outside the United States and Canada. Through our prescription medicines, vaccines, biologic therapies, and consumer care and animal health products, we work with customers and operate in more than 140 countries to deliver innovative health solutions.