Varicella-Zoster Virus (Varicella and Shingles)

A live attenuated vaccine against varicella (later also used to prevent zoster) was developed in 1974 by Takahashi and colleagues. Varicella vaccine was licensed for universal immunization of healthy children in the United States in 1995. It is also now used for this purpose in at least 15 additional countries all over the world. Varicella is disappearing in the US. Varicella vaccine has proven extremely safe and side effects are unusual, mild, and less serious than varicella or its complications. 85% of children are protected completely after 1 dose; the 15% who develop varicella despite immunization usually (but not always) have mild infections. These 15%, however, can transmit the wild type virus to others. Therefore, for optimal effect, 2 doses are required, mostly to address children who did not have an optimal primary immune response after the first dose. Waning immunity does not seem to pose a serious problem, but surveillance of vaccinees is continuing. It was demonstrated in 2005 that at a high dose of vaccine – 15 times higher than that used for prevention of varicella in children - zoster in adults can also be safely prevented. The live attenuated zoster vaccine is effective in approximately 50% of healthy individuals over age 60 who have had varicella in the past, and therefore have latent infection with varicella-zoster virus. It is given as one dose, but its effect runs out about 8 years after vaccination. In 2017, a new vaccine against zoster was also introduced. This is a subunit vaccine which does not contain contagious virus. It is even more effective than the older zoster vaccine and is over 95% effective in adults 50–≥70 years of age in preventing zoster and post herpetic neuralgia.

07. Recombinant Zoster Vaccine (RZV) Second-Dose Completion in Adults Age 50‒64 Years in the United States

Background In 2018, CDC recommended a highly efficacious adjuvanted recombinant zoster vaccine (RZV, Shingrix) as a 2-dose series for prevention of herpes zoster (HZ) for immunocompetent persons age ≥50 years, with the 2nd dose recommended 2–6 months after the 1st dose. Among Medicare beneficiaries, 2-dose series completion 6 months and 12 months post initiation was 78% and 86%, respectively. Here we estimate the proportion of adults age 50–64 years who completed the 2-dose RZV series within 6 or 12 months after receiving their 1st dose, by using two administrative claims databases. Methods We used medical and pharmaceutical claims data from October 2017‒March 2020 IQVIA® PharMetrics Plus and October 2017‒October 2020 IBM® MarketScan® databases. RZV vaccination was defined using Current Procedural Terminology and National Drug Codes. We allowed for sufficient follow-up time by examining 1st doses given at least 6 or 12 months prior to the end of the study period in both databases. Place of administration was available in IQVIA data. Results Among persons age 50‒64 years, in IQVIA and MarketScan, 70% and 68% received their 2nd RZV dose within 6 months, respectively, and 79% and 81% received their 2nd dose within 12 months, respectively. The median age of 1st dose of RZV vaccination was 60 years and ~60% were female [Table 1]. When the 2nd dose was administered within 12 months, the median interval between 1st and 2nd doses was 104 and 98 days in the IQVIA and MarketScan databases, respectively. Characteristics by age, sex, or region were similar in persons who received 1 RZV dose vs. 2 RZV doses [Table 1]. Among those who received only 1 RZV dose with at least 12 months of follow-up time, 55% of vaccinations occurred at ambulatory medical provider offices and 40% at pharmacies; among 2 doses recipients, 33% of vaccinations occurred at provider offices and 62% at pharmacies. Conclusion Among 50‒64-year-olds, 2-dose RZV series completion was ~70% within 6 months and 80% within 12 months of initiation. The findings were similar across two administrative claims databases. Availability of RZV at pharmacies has potentially helped to increase RZV 2nd dose completion rates. Disclosures All Authors: No reported disclosures

20. Cost-Effectiveness of Recombinant Zoster Vaccine for Vaccinating Immunocompromised Adults Against Herpes Zoster in the United States

Background Individuals who are immunocompromised (IC) due to disease or therapy are at increased risk of herpes zoster (HZ), with HZ cases in IC populations also resulting in increased health care resource use and costs as compared with the immunocompetent population. This study assesses the cost-effectiveness of recombinant zoster vaccine (RZV) versus no vaccine for the prevention of HZ in IC adults aged ≥ 18 years in the United States (US). Methods A Markov model with a one-year cycle length was developed to follow a hypothetical cohort of one million IC individuals for a 30-year time horizon. The model estimates health and cost outcomes associated with RZV versus no vaccine. The base-case analysis considered hematopoietic stem cell transplant (HSCT) recipients who were assumed to remain IC for five years post-transplant. Second-dose compliance was assumed to be 100%, with efficacy and waning inputs based on clinical trial data. Epidemiological, cost, and utility inputs were obtained from standard US sources and published literature. Costs and quality-adjusted life-years (QALYs) were discounted at 3% per year. Sensitivity, threshold, and scenario analyses were conducted, including scenarios of four other IC conditions. Results In the modeled hypothetical cohort of one million HSCT recipients, RZV resulted in 116,790 fewer HZ cases and 21,446 fewer postherpetic neuralgia cases versus no vaccine, 5,545 fewer QALYs lost and a societal cost-savings of &5.4 million. The number needed to vaccinate to prevent one HZ case was estimated to be 9. HSCT population results were shown to be robust in sensitivity and threshold analyses. In scenario analyses, RZV was cost saving for renal transplant recipients. Incremental cost-effectiveness ratios for other IC populations were &33,268 per QALY gained for human immunodeficiency virus, &67,682 for breast cancer, and &95,972 for Hodgkin lymphoma. Conclusion Results suggest that RZV is a cost-effective option for vaccinating US IC adults for the prevention of HZ and associated complications. Disclosures Desmond Curran, PhD, The GSK group of companies (Employee, Shareholder) Ahmed Salem, MSc, The GSK group of companies (Employee) Stéphane Lorenc, NA, GSK group of companies (Consultant) Brandon Patterson, PharmD, PhD, GSK group of companies (Shareholder) Justin Carrico, BS, GSK group of companies (Consultant)RTI Health Solutions (Employee) Katherine A. Hicks, MS, BSPH, GSK group of companies (Consultant)RTI Health Solutions (Employee) Elizabeth M. La, PhD, The GSK group of companies (Employee, Shareholder) Sara Poston, PharmD, The GSK group of companies (Employee, Shareholder) Christopher F. Carpenter, MD, MHSA, GSK group of companies (Consultant)

Recombinant adjuvanted zoster vaccine and reduced risk of COVID-19 diagnosis and hospitalization in older adults

Background: Vaccines may elicit long-term boosting of innate immune responses that can help protect against COVID-19. We evaluated the association between recombinant adjuvanted zoster vaccine (RZV) and COVID-19 outcomes at Kaiser Permanente Southern California. Methods: In a cohort design, adults aged ≥50 years who received ≥1 RZV dose prior to 3/1/2020 were matched 1:2 to unvaccinated individuals and followed until 12/31/2020. Adjusted hazard ratios (aHR) and 95% confidence intervals (CIs) for COVID-19 outcomes were estimated using Cox proportional hazards regression. In a test-negative design, cases had a positive SARS-CoV-2 test and controls had only negative tests, from 3/1/2020-12/31/2020. Adjusted odds ratios (aOR) and 95% CIs for prior receipt of RZV were estimated using logistic regression. Results: In the cohort design, 149,244 RZV recipients were matched to 298,488 unvaccinated individuals. The aHRs (95% CI) for COVID-19 diagnosis and hospitalization were 0.84 (0.81-0.87) and 0.68 (0.64-0.74), respectively. In the test-negative design, 8.4% of 75,726 test-positive cases and 13.1% of 340,898 test-negative controls had received ≥1 RZV dose. The aOR (95% CI) was 0.84 (0.81-0.86). Conclusion: RZV vaccination was associated with a 16% lower risk of COVID-19 diagnosis and 32% lower risk of hospitalization, suggesting RZV elicits heterologous protection, possibly through trained immunity.