Health technology assessment of varicella vaccine in the Armed Forces (original) (raw)
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An economic analysis of varicella immunization in the Singapore military
Military Medical Research, 2016
Background: Varicella outbreaks occur frequently in closed environments such as those of militaries. This paper compares the economic outcomes of varicella vaccination in enlisted servicemen without prior reported varicella infection or vaccination. Methods: We analyzed the economic outcomes of a varicella vaccination program on all enlisted servicemen without prior reported varicella infection or vaccination in the Singapore Armed Forces (SAF) between December 11, 2010 -December 20, 2013, compared with the previous program of varicella vaccination only for selected personnel between December 1, 2007 -December 10, 2010. Results: In the at-risk population of all active SAF servicemen, the program of varicella vaccination for all servicemen without prior reported varicella infection or vaccination upon enlistment would save 72.0 work days per 1000 (95 % CI: 61.2 -82.9), valued at SG$6,544 per 1000 (95 % CI: 6,524 -6,564), i.e., costing SG$91.5 per work day saved ). This also results in a reduction of 2.7 varicella cases per 1000 and 5.43 outbreaks per 10000, or a total savings of SG$1,695 per 1000 (95 % CI: -2,730 -6,834), taking into account the cost of work days lost over a three-year period, compared with the previous regime of vaccinations only for selected individuals. The varicella vaccination strategy targeting all enlisted servicemen without prior reported varicella infection or vaccination is able to prevent varicella infections and outbreaks, thus reducing absenteeism and days lost.
Vaccine, 2017
Infection with varicella zoster virus (VZV) produces lifelong immunity, but duration of post-vaccination immunity has not been established. The purpose of this study is to determine if a difference exists in the long-term seropositivity of anti-VZV antibodies in a cohort of young adults who were vaccinated against varicella as compared to a similar cohort with a history of chickenpox disease, and to determine which variables best predict waning seropositivity following varicella vaccination. This retrospective cohort study captures immunization and serology data from approximately 10,000 recruits who entered basic military training between January 1, 2008, and December 31, 2015, and who have childhood immunization records in the Air Force Aeromedical Services Information Management System. Varicella vaccine immunogenicity was determined relative to the immunogenicity of chickenpox disease, as measured by multiplex flow immunoassay. Among vaccine recipients, waning seroimmunity was m...
Journal of Nepal Medical Association
Introduction: Chickenpox is an acute, highly infectious disease. Outbreaks can occur in adults in closed institutional settings like hostels and barracks. This study aims to report varicella zoster outbreak among male military personnel in a military training centre. Methods: An outbreak investigation of chickenpox in a military training school and tertiary hospital was conducted. Ethical approval was taken from the Institutional Review Committee (Reference number: 267). Data was collected from February 5, 2020 to April 10, 2020 by questionnaire and clinical examination. Case definitions were prepared as per the Centre for Disease Control and Prevention criteria. Data was entered and analysed in Microsoft Excel 2010. Results: Out of the 167 male personnel in the training centre, 90 (53.89%) were susceptible to varicella and 84 (50.29%) were close contacts. The secondary attack rate of varicella zoster was 21.43% (18 cases). The mean age of the patients was 22.33±1.72 years. The mean...
Cost-effectiveness of varicella vaccination of healthcare workers
Vaccine, 2005
This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn. Health technology Four strategies for the management of future varicella cases among health care workers (HCWs) were examined. The do nothing strategy involved no testing or vaccination. Anamnestic screening consisted of screening by history of varicella, followed by antibody tests for those who are uncertain or report no prior varicella, and then vaccinating those who test negative for varicella antibody. Serotesting selection involved the vaccination of all serologically proven susceptible HCWs. Presumptive vaccination involved the mass vaccination of all eligible HCWs. Type of intervention Primary prevention (vaccination). Economic study type Cost-effectiveness analysis. Study population The study population comprised a cohort of physicians and nurses with at least 20 future potential work years (i.e. those aged younger than 45 years). Setting The setting was a hospital. The economic study was carried out in Israel. Dates to which data relate The effectiveness data and some resource use data were derived from studies published between 1990 and 2004. The price year appears to have been 2004. Source of effectiveness data The effectiveness evidence was derived from a synthesis of completed studies. Modelling A Markov model was constructed to assess the clinical and economic impact of the four strategies examined in the study. The model incorporated not only the efficacy of each intervention, but also compliance rates and accuracy of diagnostic tests. In the do nothing policy, a person could or could not already have natural protection against varicella depending on the
Varicella Susceptibility in Iran Military Conscripts: a Study Among Military Garrisons
Background: Promoting varicella vaccination for military personnel and conscripts, as one of the susceptible and high-risk groups, is an important governmental approach in every society. The present study aimed to address the seroprevalence of this infection and its immunization level among Iranian military conscripts. Objectives: This study was conducted to determine seroprevalence of varicella infection and its immunization level among Iranian military conscripts. Methods: Four hundred and sixty-four conscripts, using cluster-stratified sampling, were selected from all military garrisons in Tehran. Seroprevalence of infection among each participant was determined by measuring varicella IgG antibody level via the enzyme-linked immunosorbent assay (ELISA).
An economic analysis of varicella vaccination for health care workers
Epidemiology and Infection, 1997
A simulation model was constructed to assess the relative costs and cost-effectiveness of different screening and vaccination strategies for dealing with hospital incidents of varicella exposure, compared with current policies, using data from published sources and a hospital survey. The mean number of incidents per hospital year was 3n9, and the mean annual cost of managing these incidents was £5170. Vaccination of all staff would reduce annual incidents to 2n2 at a net cost of £48 900 per incident averted. Screening all staff for previous varicella, testing those who are uncertain or report no previous varicella, and vaccinating those who test negative for VZV antibodies, reduces annual incidents to 2n3 and gives net savings of £440 per incident averted. Sensitivity analyses do not greatly alter the ranking of the options. Some form of VZV vaccination strategy for health care workers may well prove a cost-effective use of health care resources.
Vaccine, 2013
In a cooperative agreement starting January 1995, prior to the FDA's licensure of the varicella vaccine on March 17, the Centers for Disease Control and Prevention (CDC) funded the Los Angeles Department of Health Services' Antelope Valley Varicella Active Surveillance Project (AV-VASP). Since only varicella case reports were gathered, baseline incidence data for herpes zoster (HZ) or shingles was lacking. Varicella case reports decreased 72%, from 2834 in 1995 to 836 in 2000 at which time approximately 50% of children under 10 years of age had been vaccinated. Starting in 2000, HZ surveillance was added to the project. By 2002, notable increases in HZ incidence rates were reported among both children and adults with a prior history of natural varicella. However, CDC authorities still claimed that no increase in HZ had occurred in any US surveillance site. The basic assumptions inherent to the varicella cost-benefit analysis ignored the significance of exogenous boosting caused by those shedding wild-type VZV. Also ignored was the morbidity associated with even rare serious events following varicella vaccination as well as the morbidity from increasing cases of HZ among adults. Vaccine efficacy declined below 80% in 2001. By 2006, because 20% of vaccinees were experiencing breakthrough varicella and vaccine-induced protection was waning, the CDC recommended a booster dose for children and, in 2007, a shingles vaccination was approved for adults aged 60 years and older. In the prelicensure era, 95% of adults experienced natural chickenpox (usually as children)-these cases were usually benign and resulted in long-term immunity. Varicella vaccination is less effective than the natural immunity that existed in prevaccine communities. Universal varicella vaccination has not proven to be cost-effective as increased HZ morbidity has disproportionately offset cost savings associated with reductions in varicella disease. Universal varicella vaccination has failed to provide long-term protection from VZV disease.
Successes and challenges in varicella vaccine
Therapeutic Advances in Vaccines, 2014
Varicella is a highly contagious disease caused by primary infection with varicella zoster virus (VZV). VZV infection, as well as varicella vaccination, induces VZV-specific antibody and T-cell-mediated immunity, essential for recovery. The immune responses developed contribute to protection following re-exposure to VZV. When cell-mediated immunity declines, as occurs with aging or immunosuppression, reactivation of VZV leads to herpes zoster (HZ). It has been almost 20 years since universal varicella vaccination has been implemented in many areas around the globe and this has resulted in a significant reduction of varicella-associated disease burden. Successes are reviewed here, whilst emphasis is put on the challenges ahead. Most countries that have not implemented routine childhood varicella vaccination have chosen to vaccinate high-risk groups alone. The main reasons for not introducing universal vaccination are discussed, including fear of age shift of peak incidence age and of...
Vaccine, 2005
Many models concur that universal varicella vaccination of children is beneficial from the perspective of reducing societal costs. Yet, the majority of such cost analyses have been modeled under the assumption that varicella vaccination has no adverse effect on the closely related herpes-zoster (HZ) epidemiology. Historical models have assumed that asymptomatic endogenous reactivation is the chief mechanism of boosting that suppresses the reactivation of HZ and that immunity wanes due to the aging process. Recent studies suggest instead that periodic exogenous exposures to wild-type varicella are the predominant factor influencing the curve of increasing HZ incidence rate with advancing age among individuals <50, after which an age-related decline dominates in the elderly. Based on a realistic age-structured model, we compare differences in outcomes of the number of HZ cases and direct medical costs associated with the population existing in 2000 and as it ages (according to the mortality given in the 2000 U.S. census) during the following 50 years with and without implementation of universal varicella vaccination. Under universal varicella vaccination, we assume that 15 years post-licensure, the boosting mechanism known as asymptomatic endogenous reactivation principally serves to limit HZ incidence to 550 per 100,000 person-years in unvaccinated individuals <50 with a previous history of natural varicella-since there has been a vaccine-induced decline in exogenous boosting. We estimate universal varicella vaccination has the impact of an additional 14.6 million (42%) HZ cases among adults aged <50 years during a 50 year time span at a substantial medical cost burden of US$ 4.1 billion or US$ 80 million annually utilizing an estimated mean healthcare provider cost of US$ 280 per HZ case.
Cost containment analysis of childhood vaccination against varicella in Israel
Journal of Infection, 2004
Objectives. The low cost of safe and effective vaccines prompted a costcontainment evaluation of a nationwide vaccination campaign against varicella. Methods. A model incorporating demographic, epidemiologic and economic data from Israeli sources (supplemented by data from International literature) was constructed to estimate the decrease in morbidity and the consequent reductions in treatment costs and time-off work of a nationwide programme vaccinating children at 12 months.