KIRKLAND, QC, Dec. 7, 2016 /CNW Telbec/ - Merck (NYSE: MRK), known as MSD outside Canada and the United States, today announced new data from an ongoing observational effectiveness study of single dose ZOSTAVAX® II (zoster vaccine live, attenuated [Oka/Merck], refrigerator-stable) being conducted by the Kaiser Permanente Vaccine Study Center (KPVSC) and sponsored by Merck. The study is slated to continue until 2024. The primary endpoint of the study is evaluating vaccine effectiveness and duration of protection against herpes zoster (also known as shingles). The secondary endpoint of the study is evaluating the effectiveness of the vaccine against postherpetic neuralgia (PHN), a chronic neuropathic pain complication of shingles.1 These data were the topic of a poster presentation made at the annual meeting of the Canadian Immunization Conference in Ottawa, Canada.
Results for the primary endpoint of the study analyzing effectiveness of a single dose of ZOSTAVAX II in adults 50 years of age and older in preventing shingles were presented at the ID Week 2015 conference. These data showed that vaccine effectiveness of ZOSTAVAX II against shingles was greater than 60 percent in all age groups in the first year after vaccination (65, 71, 65, and 64 percent in individuals vaccinated at 50-59, 60-69, 70-79 and ≥80 years of age, respectively); vaccine effectiveness decreased in all age groups in the second year post vaccination to an average of 47 percent across all age groups, and then decreased slowly to an average of 32 percent across all age groups in the eighth year following vaccination. The average 5-year vaccine effectiveness of a single dose of ZOSTAVAX II against shingles over the first 5 years following routine vaccination was between 44 and 49 percent among people vaccinated when 60 years of age or older (60-69, 70-79 and ≥80 years of age).
As for the secondary endpoint, the data showed that ZOSTAVAX II had a 68.7 percent (95 percent confidence interval, 64.6-72.3) overall effectiveness against PHN in the study. This overall effectiveness was calculated across all study individuals vaccinated at 50 years of age or older between 2007 and 2014, irrespective of their follow-up time up to 31 December 2014.
In the poster presented today, which included close to 49,000 shingles cases occurring between January 2007 and December 2014, the overall 68.7 percent effectiveness of ZOSTAVAX II against PHN was estimated by comparing, over time, the risk of PHN in vaccinated individuals with the risk in otherwise similar individuals who were unvaccinated at that time. Vaccine effectiveness against PHN by age at vaccination and by year since vaccination was estimated using Cox regression model adjusted for sex, year of birth, race/ethnicity, and several time-varying variables, including healthcare use, comorbid conditions and immune-compromise status. In the first year following vaccination, vaccine effectiveness against PHN was 82.4 percent for all ages combined. Vaccine effectiveness against PHN decreased to 66.1 percent in the second year for all ages combined, and then remained relatively stable through year 7, although numbers of PHN cases became small beyond 6 years following vaccination. The vaccine effectiveness over the entire study period, by age at vaccination, ranged approximately from 60 to 70 percent across the age groups evaluated; (it was 63, 71, 70 and 62 percent in individuals vaccinated at 50-59, 60-69, 70-79 and ≥80 years of age, respectively).
For each age group at vaccination, an average five-year vaccine effectiveness over the first five years following vaccination was also calculated as an average of the first five yearly vaccine effectiveness estimates from the Cox model. In the 2007-2014 study period, the average five-year vaccine effectiveness against PHN was 61 percent (95% confidence interval, 47-71 percent), 69 and 72 percent among those vaccinated at 80 years of age or older, 70-79 and 60-69 years of age, respectively.
"In this observational effectiveness study, ZOSTAVAX II showed vaccine effectiveness against shingles. The data also demonstrated effectiveness against postherpetic neuralgia in all age groups studied, and this continued for at least five years after vaccination, in those vaccinated at 60 years of age or older," said Eddy Bresnitz MD, CM, Executive Director, Global Health and Medical Affairs, Merck Vaccines. "These effectiveness data underscore the benefit of the vaccine in a real world setting".
1 Postherpetic neuralgia (PHN), the most common complication of herpes zoster, is pain persisting in the area of the rash after rash resolution. The duration of pain used to define PHN varies, ranging from any duration to more than 90 days after rash onset or resolution. PHN can last for weeks, months or even years. A person's risk of having PHN after herpes zoster increases with age. Older adults are also more likely to have longer lasting and more severe pain.
About the Study
The study is being conducted at Kaiser Permanente Northern California (KPNC) as an open cohort that KPNC members enter when they become age-eligible for ZOSTAVAX II. From January 2007 to December 2014, over 1.3 million study subjects 50 years of age and older, including close to 392,000 who received one dose of ZOSTAVAX II, contributed approximately 5.8 million person-years of follow-up and experienced approximately 49,000 shingles episodes and 3,538 PHN episodes. This is the largest observational effectiveness study of ZOSTAVAX II conducted to date.
Cases of shingles were identified using an algorithm based on information on zoster diagnosis and treatment from the study databases, after confirming the high positive predictive value (ability to accurately identify zoster cases) of the algorithm of 98% during the study pilot phase. Cases of PHN were identified using an algorithm requiring a PHN diagnosis for healthcare contact and/or treatment between 90 days and a year after the first zoster diagnosis. One subcategory of PHN cases, representing 1,551 (44%) of the 3,538 potential PHN cases identified by the algorithm, were accepted without further chart review based on a high positive predictive value of 96% in the study pilot phase. The other 1,987 (56%) potential PHN cases identified by the algorithm were all chart reviewed to confirm them as PHN cases (89% confirmation rate, resulting in an additional 1,765 cases). In this analysis, the evaluation of vaccine effectiveness against HZ and PHN was based on a comparison of the risk of HZ (or PHN) in vaccinated individuals with that in a reference group of individuals unvaccinated at that time but otherwise similar. Specifically, VE was estimated by age at vaccination (50-59, 60-69, 70-79 and ≥80 years of age groups) and by year since vaccination, using Cox proportional hazards regression models with calendar time as the timeline, stratified by birth year, and adjusted for sex, race/ethnicity, and several time-varying variables, including healthcare use, comorbid conditions and immune-compromise status at the time of risk.
In the study, PHN cases were identified based on PHN diagnosis codes between 90 days and a year following shingles onset and validated by chart review.
About ZOSTAVAX II
ZOSTAVAX II (zoster vaccine live, attenuated [Oka/Merck], refrigerator-stable) is a live attenuated virus vaccine (a lyophilized preparation of the Oka/Merck strain of varicella-zoster virus). ZOSTAVAX II is indicated for the prevention of herpes zoster (shingles). ZOSTAVAX II is indicated for immunization of individuals 50 years of age or older. ZOSTAVAX II is not a treatment for zoster or PHN. If an individual develops herpes zoster despite vaccination, active current standard of care treatment for herpes zoster should be considered.
Zostavax II is administered as a single dose, subcutaneously, preferably into the upper arm - deltoid region. ZOSTAVAX II is currently the only available preventative means against shingles.
To consult the full Canadian product monograph for complete prescribing information and contraindications, warnings, precautions, adverse reactions, interactions, dosing, and conditions of clinical use, please click here
About Herpes Zoster
Shingles (also known as herpes zoster) is a common and potentially debilitating disease caused by the reactivation of the chickenpox (varicella virus) that most people host in the nervous system since childhood. For reasons that still remain unknown, the virus can become active again in the form of shingles.
The vaccine works by boosting natural immunity to act specifically against the varicella-zoster virus. About 90% of Canadians have had chickenpox1, and it is estimated that nearly 1 out of 3 people will develop shingles in their lifetime2. The risk of getting shingles increases after the age of 50.3
1. Immunize Canada, 2014. Herpes Zoster (Shingles). Available online: http://www.immunize.ca/en/diseases-vaccines/herpeszoster.aspx (Accessed November 2015)
2. CPS, 2010. The Canadian Pain Society supports the NACI recommendations on shingles vaccination. Available online: http://www.newswire.ca/news-releases/the-canadian-pain-society-supports-the-naci-recommendations-on-shinglesvaccination-539273491.html (Accessed November 2015)
3. PHAC, 2013. Fact Sheet – Shingles (Herpes Zoster). Available online: http://www.phac-aspc.gc.ca/id-mi/shingles-zona-fs-eng.php (Accessed November 2015)
About Merck in Canada
For 125 years, Merck has been a global healthcare leader working to help the world be well. Merck is known as MSD outside Canada and the United States. Through our prescription medicines, vaccines, biologic therapies, and animal health products, we work with customers and operate in more than 140 countries to deliver innovative health solutions. We also demonstrate our commitment to increasing access to healthcare through far-reaching policies, programs and partnerships. For more information about our operations in Canada, visit www.merck.ca and connect with us on YouTube.
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