Methods: The study is conducted at Kaiser Permanente Northern California (KPNC). The study design is an open cohort; KPNC members enter the study when they become age-eligible for the vaccine. Incident HZ is defined as a new HZ episode without evidence of HZ in the prior year. This preliminary analysis included HZ cases identified by having a diagnosis code of HZ with an antiviral prescription or a positive varicella viral test. VE by time since vaccination was estimated using Cox regression adjusted for sex, age, race/ethnicity, and several time-varying variables, including healthcare use, comorbid conditions and immune-compromise status. A variable was included in the model for each year since vaccination; risk sets were anchored to a calendar timeline. Average VE at 5 years was calculated as a weighted average of annual VE.
Results: From 2007 through 2013, a total of 303,828 of the ~1.3 million study participants received one dose of Zostavax, with 23,477 of those participants vaccinated at age 50-59. As of 2013, vaccine coverage was >40% in 60+ but only 4% in 50-59. In all age groups (50-59, 60-69, 70-79 and 80+ years at the time of vaccination), VE in preventing HZ was >60% during the 1st year following vaccination (70%, 73%, 65% and 64%, respectively), and decreased in the following years. For all ages combined, VE was 69% (95% CI 66% -71%) during the first year after immunization, then fell to 45% (42%-49%), 38% (33%-42%), 41% (36%-42%), and 38% (#2%-44%) in years 2, 3, 4, and 5, respectively. Overall, the average VE in preventing HZ over 5 years of follow-up was 50% (95%CI, 47%-52%), 45% (41%-48%) and 45% (38%-50%) among individuals vaccinated at 60-69, 70-79, and 80+ years, respectively. In 50-59, average VE was 62% over 3 years.
Conclusion: We found effectiveness of live zoster vaccine in routine use to be 69% during year one, with evidence of waning after that. Average VE of a single dose over 5 years following routine vaccination was between 45%-50% among people 60+.
GSK: Grant Investigator , Research grant
Pfizer: Grant Investigator , Research grant
Sanofi Pasteur: Grant Investigator , Research grant
B. Fireman, None
M. Marks, Merck Sharp & Dohme, Inc.: Employee and Shareholder , Salary
J. Hansen, None
N. Lewis, None
L. Aukes, None
Y. Chen, Merck & Co., Inc.: Employee and Shareholder , Salary
P. Saddier, Merck Sharp & Dohme, Corp.: Employee and Shareholder , Salary