Use Of Varicella Vaccine Research Articles

Cost-effectiveness of varicella vaccine against herpes zoster and post-herpetic neuralgia for elderly in Japan

BackgroundThe extended use of varicella vaccine in adults aged 50 and older against herpes zoster (HZ) was recently approved in Japan, which has raised the need to evaluate its value for money. MethodsWe conducted a cost-effectiveness analysis with Markov modelling to evaluate the efficiency of varicella vaccine immunisation programme for the elderly in Japan. Four strategies with different ages to receive a shot of vaccine were set, namely: (1) 65–84, (2) 70–84, (3) 75–84 and (4) 80–84years old (y.o.). Incremental cost-effectiveness ratios (ICERs) compared with no programme from societal perspective were calculated. The health statuses following the target cohort are as follows: without any HZ-related disease, acute HZ followed by recovery, post-herpetic neuralgia (PHN) followed by recovery, post HZ/PHN, and general death. The transition probabilities, utility weights to estimate quality-adjusted life year (QALY) and disease treatment costs were either calculated or cited from literature. Costs of per course of vaccination were assumed at ¥10,000 (US$91). The model with one-year cycle runs until the surviving individual reached 100 y.o. ResultsICERs ranged from ¥2,812,000/US$25,680 to ¥3,644,000/US$33,279 per QALY gained, with 65–84 y.o. strategy having the lowest ICER and 80–84 y.o. strategy the highest. None of the alternatives was strongly dominated by the other, while 80–84 y.o. and 70–84 y.o. strategy were extendedly dominated by 65–84 y.o. strategy. Probabilistic sensitivity analyses showed that the probabilities that ICER is under ¥5,000,000/US$45,662 per QALY gained was at 100% for 65–84 y.o., 70–84 y.o., 75–84 y.o. strategy, respectively, and at 98.4% for 80–84 y.o. strategy. ConclusionWe found that vaccinating individuals aged 65–84, 70–84, 75–84, and 80–84 with varicella vaccine to prevent HZ-associated disease in Japan can be cost-effective from societal perspective, with 65–84 y.o. strategy as the optimal alternative. Results are supported by one-way sensitivity analyses and probabilistic sensitivity analyses.

Epidemiological situation of chickenpox in Qatar (2012-2014)

Background: Chickenpox is a contagious viral disease that affects any age group. Chickenpox is the most common infectious disease in Qatar. Most affected age groups in Qatar in the last three years are children. Chickenpox vaccination has been included in Qatar National Immunization Program in 2000. Aim: To describe the epidemiological characteristics of chickenpox in Qatar in the year 2012–2014. Methods: Descriptive analysis based on data retrieved from routine surveillance system, Qatar Information Exchange, Ministry Of Development Planning And Statistics and National Immunization Program. Incidence rate was calculated for each year by gender and age groups. Results: Total number of chickenpox cases registered in Qatar in 2014 was 574 with the incidence (259.1 per 100,000) which was higher than 2012 (244.5) and 2013 (237.4). Most affected age groups in 2012 and 2013 were 5–9 years old (105.6 per 10,000) and (82.7 per 10,000) respectively while in 2014 age group 0–4 was most affected one (87.9 per 10,000). There was a remarkable increase in the incidence rate of chickenpox in the age groups 15–19, 45–49 and 50+ in 2014 comparing to 2012 and 2013. Although the number of affected cases was higher among men comparing to women, the incidence rate in men was lower. Conclusion: Increase of incidence rate in 2014 comparing to 2012 and 2013 influenced by the increase of the incidence rate in middle and older age groups. Our results indicate that more evidence is needed to recommend use of varicella vaccine in adults and not only in children.

Update on Incidence of Herpes Zoster Among Children and Adolescents After Implementation of Varicella Vaccination, Antelope Valley, CA, 2000 to 2010.

Changes in herpes zoster (HZ) epidemiology are expected with childhood varicella vaccination. We reported previously that during 2000 to 2006 HZ incidence decreased 55% in children <10 years of age, while among 10- to 19-year olds it increased by 63%. We update the analysis with 4 additional years of data. Population-based active surveillance was conducted for HZ in Antelope Valley, California. Structured telephone interviews and medical chart reviews collected data on demographics, varicella vaccinations, disease histories and clinical information. We calculated HZ incidence for 2007 to 2010 and assessed trends since 2000. Among children <10 years of age, HZ incidence continued the decreasing trend previously reported. During 2007 to 2010, the average incidence was 12.8 cases/100,000 children compared with 41.6 cases/100,000 children during 2000 to 2006, a 69% decline (P < 0.0001). For the 10- to 19-year olds, during 2007 to 2010 HZ incidence did not continue the increasing trend reported from 2000 to 2006; lower rates than in 2006 were observed in 3 of the 4 additional years evaluated. During 2007 to 2010 the average incidence was 78.2 cases/100,000 children compared with 68.0 cases/100,000 children during 2000 to 2006, a 13% increase (P = 0.123), with substantial fluctuation in annual rates throughout the 11 years of surveillance. During the mature varicella vaccination program, declines in HZ incidence among children <10 years of age continued through 2010. Among the 10- to 19-year olds, the increase reported through 2006 did not continue further and lower rates than in 2006 were observed through 2010. Widespread use of varicella vaccine could reduce HZ incidence among vaccinated populations. Ongoing monitoring of HZ incidence is needed to detect and understand changes in HZ epidemiology in the varicella vaccine era.

Varicella and herpes zoster vaccines: WHO position paper, June 2014 – Recommendations

This article presents the World Health Organization's (WHO) recommendations for the use of varicella and herpes zoster vaccination from the WHO position paper on varicella and herpes zoster vaccines – June 2014, published in the Weekly Epidemiological Record [1]. This position paper summarizes the WHO position on the use of varicella and herpes zoster vaccines. The current document replaces the position paper on the use of varicella vaccines published in 1998 [2].Footnotes to this paper provide a number of core references. In accordance with its mandate to provide guidance to Member States on health policy matters, WHO issues a series of regularly updated position papers on vaccines and combinations of vaccines against diseases that have an international public health impact. These papers are concerned primarily with the use of vaccines in large-scale immunization programmes; they summarize essential background information on diseases and vaccines, and conclude with WHO's current position on the use of vaccines in the global context. This paper reflects the recommendations of WHO's Strategic Advisory Group of Experts (SAGE) on immunization. These recommendations were discussed by SAGE at its April 2014 meeting. Evidence presented at the meeting can be accessed at http://www.who.int/immunization/sage/previous/en/index.html.

Live attenuated herpes zoster vaccine for HIV-infected adults.

Multiple guidelines exist for the use of live viral vaccines for measles-mumps-rubella (MMR), varicella and yellow fever in people with HIV infections, but these guidelines do not make recommendations regarding live attenuated herpes zoster vaccine (LAHZV), which is approved for people over 50 years in the general population. LAHZV is made with the same virus used in varicella vaccine. The incidence of herpes zoster remains increased in people with HIV infection, even when on suppressive antiretroviral therapy, and a growing proportion of HIV-infected patients are over 50 years of age. The purpose of this article is to review the use of varicella vaccine and LAHZV in people with HIV infection and to make recommendations about the use of LAHZV in adults with HIV infection. A PubMed search was undertaken using the terms 'herpes zoster AND HIV' and 'varicella AND HIV'. Reference lists were also reviewed for pertinent citations. Varicella vaccine is recommended in varicella-susceptible adults, as long as they have a CD4 count > 200 cells/μL, the same CD4 threshold used for MMR and yellow fever vaccines. No transmission of vaccine strain Varicella zoster virus has been documented in people with HIV infections with a CD4 count above this threshold. LAHZV was administered to 295 HIV-infected adults with a CD4 count > 200 cells/μL, and was safe and immunogenic with no cases of vaccine strain infection. It is recommended that LAHZV be administered to HIV-infected adults with a CD4 count above 200 cells/μL, the same CD4 threshold used for other live attenuated viral vaccines.

Vaccines for post-exposure prophylaxis against varicella (chickenpox) in children and adults.

The prevention of varicella (chickenpox) using live attenuated varicella vaccines has been demonstrated both in randomised controlled trials (RCTs) and in population-based immunisation programmes in countries such as the United States and Australia. Many countries do not routinely immunise children against varicella and exposures continue to occur. Although the disease is often mild, complications such as secondary bacterial infection, pneumonitis and encephalitis occur in about 1% of cases, usually leading to hospitalisation. The use of varicella vaccine in persons who have recently been exposed to the varicella zoster virus has been studied as a form of post-exposure prophylaxis (PEP). To assess the efficacy and safety of vaccines for use as PEP for the prevention of varicella in children and adults. We searched CENTRAL (2014, Issue 1), MEDLINE (1966 to March week 1, 2014), EMBASE (January 1990 to March 2014) and LILACS (1982 to March 2014). We searched for unpublished trials registered on the clinicaltrials.gov and WHO ICTRP websites. RCTs and quasi-RCTs of varicella vaccine for PEP compared with placebo or no intervention. The outcome measures were efficacy in prevention of clinical cases and/or laboratory-confirmed clinical cases and adverse events following vaccination. Two review authors independently extracted and analysed data using Review Manager software. We identified three trials involving 110 healthy children who were siblings of household contacts. The included trials varied in study quality, vaccine used, length of follow-up and outcomes measured and, as such, were not suitable for meta-analysis. We identified high or unclear risk of bias in two of the three included studies. Overall, 13 out of 56 vaccine recipients (23%) developed varicella compared with 42 out of 54 placebo (or no vaccine) recipients (78%). Of the vaccine recipients who developed varicella, the majority only had mild disease (with fewer than 50 skin lesions). In the three trials, most participants received PEP within three days following exposure; too few participants were vaccinated four to five days post-exposure to ascertain the efficacy of vaccine given more than three days after exposure. No included trial reported on adverse events following immunisation. These small trials suggest varicella vaccine administered within three days to children following household contact with a varicella case reduces infection rates and severity of cases. We identified no RCTs for adolescents or adults. Safety was not adequately addressed.

Impact of Varicella Vaccination on Varicella-related Hospitalizations Among American Indian/Alaska Native People

Routine childhood varicella vaccination, implemented in 1995, has resulted in significant declines in varicella-related hospitalizations in the United States. Varicella hospitalization rates among the American Indian (AI) and Alaska Native (AN) population have not been previously documented. We selected varicella-related hospitalizations, based on a published definition, from the Indian Health Service inpatient database for AI/ANs in the Alaska, Southwest and Northern Plains regions (1995-2010) and from the Nationwide Inpatient Sample for the general US population (2007-2010). We analyzed average annual hospitalization rates prevaccine (1995-1998) and postvaccine (2007-2010) for the AI/AN population, and postvaccine for the general US population. From 1995-1998 to 2007-2010, the average annual varicella-related hospitalization rate for AI/ANs in the 3 regions decreased 95% (0.66-0.03/10,000 persons); the postvaccine rate appears lower than the general US rate (0.06, 95% confidence interval: 0.05-0.06). The rate declined in all AI/AN pediatric age groups. Infants experienced the highest prevaccine (14.07) and postvaccine (0.83) hospitalization rates. Adults experienced low rates in both periods. Varicella vaccination rates in 19- to 35-month-old AI/AN children during fiscal years 2008-2010 were 88.1-91.0%. Widespread use of varicella vaccine in AI/AN children was accompanied by substantial declines in varicella-related hospitalizations consistent with high varicella vaccine effectiveness in preventing severe varicella outcomes.

Varicella After the Perinatal Period

1. Molly C. Berkoff, MD, MPH 2. Wallace D. Brown, MD 1. Department of Pediatrics, Division of General Pediatrics and Adolescent Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC. 1. Acyclovir for Treating Varicella in Otherwise Healthy Children and Adolescents. Klassen TP, Hartling L. Cochrane Database Syst Rev. 2005;(4):CD002980 2. FDA Approval of an Extended Period for Administering VariZIG for Postexposure Prophylaxis of Varicella. MMWR Morb Mortal Wkly Rep . 2012;61(12):212 3. Prevention of Varicella: Recommendations for Use of Varicella Vaccines in Children, Including a Recommendation for a Routine 2-Dose Varicella Immunization Schedule. American Academy of Pediatrics Committee on Infectious Diseases. Pediatrics. 2007;120(1):221–231 [OpenUrl][1][Abstract/FREE Full Text][2] 4. Changing Varicella Epidemiology in Active Surveillance Sites-United States, 1995–2005. Guris D, Jumaan AO, Mascola L, et al. J Infect Dis. 2008:197(suppl 2):S71–S75 Formerly a common childhood infection that affected almost all children, varicella (chickenpox) is now relatively uncommon because of successful prevention with universal vaccination. Before available immunization, approximately 4 million cases of varicella disease were reported annually. By 2005, active surveillance sites documented a decrease in the incidence of varicella of approximately 90%. Varicella is the primary clinical manifestation of infection with varicella-zoster virus. The initial infection with the virus occurs from exposure to an infected person, and transmission occurs through contact with the respiratory tract, conjunctiva, and skin lesions. Approximately 80% to 90% of susceptible individuals will acquire the infection after exposure to an infected individual. After an incubation period of 10 to 21 days, an infected individual may experience a brief prodrome, including fever and malaise, for 2 days before the development of a pruritic rash containing 250 to 500 lesions in an unimmunized person. Lesions appear in crops and contain vesicles on an erythematous base, which eventually scab. Children who have been immunized and have breakthrough varicella typically will have fewer lesions (<50 … [1]: {openurl}?query=rft.jtitle%253DPediatrics%26rft.stitle%253DPediatrics%26rft.issn%253D0031-4005%26rft.aulast%253DCommittee%2Bon%2BInfectious%2BDiseases%26rft.auinit1%253D%2B%26rft.volume%253D120%26rft.issue%253D1%26rft.spage%253D221%26rft.epage%253D231%26rft.atitle%253DPrevention%2Bof%2BVaricella%253A%2BRecommendations%2Bfor%2BUse%2Bof%2BVaricella%2BVaccines%2Bin%2BChildren%252C%2BIncluding%2Ba%2BRecommendation%2Bfor%2Ba%2BRoutine%2B2-Dose%2BVaricella%2BImmunization%2BSchedule%26rft_id%253Dinfo%253Adoi%252F10.1542%252Fpeds.2007-1089%26rft_id%253Dinfo%253Apmid%252F17606582%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [2]: /lookup/ijlink?linkType=ABST&journalCode=pediatrics&resid=120/1/221&atom=%2Fpedsinreview%2F34%2F11%2F537.atom

Association of asthma and herpes zoster in children

The incidence of asthma and herpes zoster (HZ) rose concurrently at the end of the 20th century. Investigators took advantage of the setting of Olmstead County, Minnesota, where medical care is “virtually self-contained,” to perform a population-based epidemiologic study to explore whether HZ was associated with asthma. The study was performed before substantial use of varicella vaccine, and no case had received systemic corticosteroid in the three months prior to HZ. Twenty-three percent of cases of HZ had asthma compared with 12.6% of matched controls (aOR: 2.09, 95% CI 1.24-3.52; P = .006). The authors provide arguments about why detection bias is likely not responsible for their finding. They conclude that asthma may be an unrecognized risk factor for reactivation of non—airway-related latent VZV infection and speculate that altered cell-mediated innate immune response could be the biologic link.Article page 816▶ The incidence of asthma and herpes zoster (HZ) rose concurrently at the end of the 20th century. Investigators took advantage of the setting of Olmstead County, Minnesota, where medical care is “virtually self-contained,” to perform a population-based epidemiologic study to explore whether HZ was associated with asthma. The study was performed before substantial use of varicella vaccine, and no case had received systemic corticosteroid in the three months prior to HZ. Twenty-three percent of cases of HZ had asthma compared with 12.6% of matched controls (aOR: 2.09, 95% CI 1.24-3.52; P = .006). The authors provide arguments about why detection bias is likely not responsible for their finding. They conclude that asthma may be an unrecognized risk factor for reactivation of non—airway-related latent VZV infection and speculate that altered cell-mediated innate immune response could be the biologic link. Article page 816▶ Increased Risk of Herpes Zoster in Children with Asthma: A Population-Based Case-Control StudyThe Journal of PediatricsVol. 163Issue 3PreviewTo determine the risk of herpes zoster (HZ) in children with and without asthma. Full-Text PDF

Varicella-Zoster Virus

Widespread use of varicella vaccine in the United States has drastically changed the epidemiology of the disease. Although chickenpox is no longer a ubiquitous childhood infection, varicella-zoster virus continues to circulate in the community and nonimmune pregnant women remain at risk. Varicella can cause severe infection in pregnant women, often complicated by viral pneumonia. Maternal varicella occurring in the first half of pregnancy can cause the rare but devastating congenital varicella syndrome, whereas infection in the late stages of pregnancy may cause neonatal varicella. The best approach to avoiding the morbidity and mortality associated with chickenpox in pregnancy is to screen and vaccinate susceptible reproductive-age women.

Varicella-zoster virus infections in immunocompromised patients - a single centre 6-years analysis

BackgroundInfection with varicella-zoster virus (VZV) contemporaneously with malignant disease or immunosuppression represents a particular challenge and requires individualized decisions and treatment. Although the increasing use of varicella-vaccines in the general population and rapid initiation of VZV-immunoglobulins and acyclovir in case of exposure has been beneficial for some patients, immunocompromised individuals are still at risk for unfavourable courses.MethodsIn this single center, 6-year analysis we review incidence, hospitalization and complication rates of VZV-infections in our center and compare them to published data. Furthermore, we report three instructive cases.ResultsHospitalization rate of referred children with VZV-infections was 45%, among these 17% with malignancies and 9% under immunosuppressive therapy. Rate of complications was not elevated in these two high-risk cohorts, but one ALL-patient died due to VZV-related complications. We report one 4-year old boy with initial diagnosis of acute lymphoblastic leukemia who showed a rapidly fatal outcome of his simultaneous varicella-infection, one 1.8-year old boy with an identical situation but a mild course of his disease, and an 8.5-year old boy with a steroid-dependent nephrotic syndrome. This boy developed severe hepatic involvement during his varicella-infection but responded to immediate withdrawl of steroids and administration of acyclovir plus single-dose cidofovir after nonresponse to acyclovir after 48 h.ConclusionOur data show that patients with malignant diseases or immunosuppressive therapy should be hospitalized and treated immediately with antiviral agents. Despite these measures the course of VZV-infections can be highly variable in these patients. We discuss aids to individual decision-making for these difficult situations.

Chickenpox at Ninety Four: A Case for Extending the Use of Varicella Vaccine in the UK

A case of chickenpox in a 94-year-old female is described. Serological tests for Varicella zoster virus (VZV) performed on early and late serum samples confirmed primary VZV infection. The patient recovered but seventeen days after presentation she developed a stroke from which she subsequently died. Chickenpox in older people is relatively rare—this case may be the oldest case of laboratory-proven chickenpox described—but it is a life-threatening illness. The varicella vaccine is licensed for use in immunocompetent persons of 12 months of age or older but in the UK is only offered to susceptible healthcare workers and close contacts of immunocompromised patients. In the US, the vaccine is recommended for all susceptible adolescents and adults. The same recommendation should be made in the UK.

The Incidence and Clinical Characteristics of Herpes Zoster Among Children and Adolescents After Implementation of Varicella Vaccination

The varicella-zoster virus (VZV) vaccine strain may reactivate to cause herpes zoster. Limited data suggest that the risk of herpes zoster in vaccinated children could be lower than in children with naturally acquired varicella. We examine incidence trends, risk and epidemiologic and clinical features of herpes zoster disease among children and adolescents by vaccination status. Population-based active surveillance was conducted among <20 years old residents in Antelope Valley, California, from 2000 through 2006. Structured telephone interviews collected demographic, varicella vaccination and disease histories, and clinical information. From 2000 to 2006, the incidence of herpes zoster among children<10 years of age declined by 55%, from 42 cases reported in 2000 (74.8/100,000 persons; 95% confidence interval [95% CI]: 55.3-101.2) to 18 reported in 2006 (33.3/100,000; 95% CI: 20.9-52.8; P<0.001). During the same period, the incidence of herpes zoster among 10- to 19-year-olds increased by 63%, from 35 cases reported in 2000 (59.5/100,000 persons; 95% CI: 42.7-82.9) to 64 reported in 2006 (96.7/100,000; 95% CI: 75.7-123.6; P<0.02). Among children aged<10 years, those with a history of varicella vaccination had a 4 to 12 times lower risk for developing herpes zoster compared with children with history of varicella disease. Varicella vaccine substantially decreases the risk of herpes zoster among vaccinated children and its widespread use will likely reduce overall herpes zoster burden in the United States. The increase in herpes zoster incidence among 10- to 19-year-olds could not be confidently explained and needs to be confirmed from other data sources.

Varicella Vaccination of Immunocompromised Children

Exposure of immunocompromised children to varicella often requires postexposure prophylaxis. Exposures requiring this management are often not recognized. Varicella can be a severe disease when it occurs in immunocompromised children, in spite of antiviral therapy. Varicella exposure and varicella in these children can also disrupt scheduled therapy for their underlying illness. Both postexposure prophylaxis and treatment of varicella are likely to be expensive and use significant medical resources. Numerous trials have been undertaken to vaccinate children who are immunocompromised by a variety of conditions and therapies that depress their immune function. Clinical trials of varicella vaccine administration to immunocompromised children that were reported since 1975 were identified in the Ovid medical database. Reports were selected for analysis and discussion on the basis of their completeness and the utility of their conclusions. Vaccination before immune compromise is discussed as a strategy for some settings. The obstacles, potential opportunities, and success in varicella vaccination for immunocompromised children are separately analyzed for (1) children with leukemia and other malignancies, (2) human immunodeficiency virus-infected children, and (3) children with hematopoietic stem cell or solid-organ transplantation. Vaccination before immune compromise is often successful, and the vaccine-induced response is usually partially or fully protective. In many treatment settings, it is possible to safely vaccinate once the level of immune suppression has been reduced. Targets for future research are outlined. A consensus conference should be undertaken to develop guidelines for the use of varicella vaccine in immunocompromised children.

Varicella Vaccination in Japan, South Korea, and Europe

The most extensive use of varicella vaccine has been in the United States and Canada, where it is universally recommended. However, a number of other countries now have recommendations for use of the vaccine, which has been expanding in Europe and Latin America. In this article, we review information concerning varicella vaccination in Japan, where the vaccine was first developed, and in South Korea and parts of Europe. Despite the worldwide availability of an efficient vaccine, varicella vaccination policy is highly variable from country to country. The recent development of a tetravalent vaccine against measles, mumps, rubella, and varicella could modify this variability in the future. It is evident that efforts to control varicella will spread gradually to all continents.

Safety of Varicella Vaccine after Licensure in the United States: Experience from Reports to the Vaccine Adverse Event Reporting System, 1995–2005

Widespread use of varicella vaccine in the United States could enable detection of rare adverse events not identified previously. We reviewed data from 1995 to 2005 from the Vaccine Adverse Event Reporting System, including data from laboratory analyses, to distinguish adverse events associated with wild-type varicella-zoster virus (VZV) versus those associated with vaccine strain. Almost 48 million doses of varicella vaccine were distributed between 1995 and 2005. There were 25,306 adverse events reported (52.7/100,000 doses distributed); 5.0% were classified as serious (2.6/100,000 doses distributed). Adverse events associated with evidence of vaccine-strain VZV included meningitis in patients with concurrent herpes zoster. Patients with genetic predispositions may rarely have disease triggered by receipt of varicella vaccine. Overall, serious adverse events reported after varicella vaccination continue to be rare and must be considered relative to the substantial benefits of varicella vaccination. Ongoing safety surveillance and further studies may shed light on some of the hypothesized associations.

Varicella vaccination in HIV-positive individuals – a time to act

Purpose of the study Primary varicella infection in the HIV population can have serious sequelae. The HIV non-VZV immune population is at risk of attack rates of up to 90% from infected household contacts, who are predominantly children. Universal childhood varicella vaccination is currently under review in Ireland. New recommendations of the Advisory Committee on Immunisation Practices (MMWR) 2007 include expanding the use of varicella vaccine for HIV-infected adults and adolescents with CD4 >200, with vaccination of household contacts of those with CD4<200. These guidelines prompted us to review our HIV patient cohort, 30% of whom are from sub-Saharan Africa (SSA), reflecting the changing demographics of the Irish population. VZV non-immunity is known to be higher in the SSA population.

Prevention of Varicella: Recommendations for Use of Varicella Vaccines in Children, Including a Recommendation for a Routine 2-Dose Varicella Immunization Schedule

National varicella immunization coverage using the current 1-dose immunization strategy has increased among vaccine-eligible children 19 through 35 months of age from 27% in 1997 to 88% by 2005. These high immunization rates have resulted in a 71% to 84% decrease in the reported number of varicella cases, an 88% decrease in varicella-related hospitalizations, a 59% decrease in varicella-related ambulatory care visits, and a 92% decrease in varicella-related deaths in 1- to 4-year-old children when compared with data from the prevaccine era. Despite this significant decrease, the number of reported cases of varicella has remained relatively constant during the past 5 to 6 years. Since vaccine effectiveness for prevention of disease of any severity has been 80% to 85%, a large number of cases of varicella continue to occur among people who already have received the vaccine (breakthrough varicella), and outbreaks of varicella have been reported among highly immunized populations of schoolchildren. The peak age-specific incidence has shifted from 3- to 6-year-old children in the prevaccine era to 9- to 11-year-old children in the postvaccine era for cases in both immunized and unimmunized children during these outbreaks. Outbreaks of varicella are likely to continue with the current 1-dose immunization strategy. After administration of 2 doses of varicella vaccine in children, the immune response is markedly enhanced, with > 99% of children achieving an antibody concentration (determined by glycoprotein enzyme-linked immunosorbent assay) of > or = 5 U/mL (an approximate correlate of protection) and a marked increase in geometric mean antibody titers after the second vaccine dose. The estimated vaccine efficacy over a 10-year observation period of 2 doses for prevention of any varicella disease is 98% (compared with 94% for 1 dose), with 100% efficacy for prevention of severe disease. Recipients of 2 doses of varicella vaccine are 3.3-fold less likely to have breakthrough varicella, compared with those who are given 1 dose, during the first 10 years after immunization. To achieve greater levels of immunity with fewer serosusceptible people, greater protection against breakthrough varicella disease, and reduction in the number of outbreaks that occur nationwide among school-aged populations, a 2-dose varicella immunization strategy is now recommended for children > or = 12 months of age.

Varicella-Related Hospitalization and Emergency Department Visit Rates, Before and After Introduction of Varicella Vaccine, Among White and Black Children in Hamilton County, Ohio

The American Academy of Pediatrics recommended routine use of varicella vaccine in pediatric practice in 1995. We examined the impact of varicella immunization on population-based rates of pediatric varicella-related hospitalizations and emergency department (ED) visits in the years before and after introduction of varicella vaccine. Discharge data for hospitalizations and ED encounters from 1990 through 2003 were queried for patients <20 years of age with varicella International Classification of Diseases, Ninth Revision, Clinical Modification codes (052.0-052.9) in any diagnostic position. Addresses were geocoded for identification of Hamilton County, Ohio, residents. Rates were calculated according to year, age, and race, with census estimates. During the 14-year study period, there were 3983 incident varicella cases; 335 patients were hospitalized and 3833 were treated only in the ED. The rate of varicella-related hospitalizations decreased from 15.7 cases per 100,000 population to 5.5 cases per 100,000 population between the prevaccine period (1990-1995) and the postvaccine period (1996-2003); varicella-related ED use decreased from 178.2 cases per 100,000 population to 61.2 cases per 100,000 population. In the prevaccine period, hospitalization and ED visit rates were significantly higher for black children than for white children. In the postvaccine period, hospitalization rates did not differ according to race but ED visit rates remained significantly higher for black children, compared with white children. Varicella-related hospitalization and ED visit rates decreased significantly for both white and black children in Hamilton County, Ohio, after the introduction of varicella vaccine, and the racial disparity found before licensure decreased after licensure.

Commentary: The Case for Universal Varicella Immunization

The article in this month’s issue on immunity to the varicella-zoster virus (VZV) in France highlights the fact that varicella is primarily a childhood disease and that prevention of varicella and its attendant morbidity and mortality require the universal vaccination of children. Yet despite the availability of a safe and effective vaccine, many countries in Europe and the industrialized world, at present, have not included varicella vaccine in their routine immunization programs. 1 Considered by many physicians to be a benign disease, varicella can result in serious complications, sequelae and death. In the United States, before use of varicella vaccine, there were an average of 4 million cases of varicella that resulted in 10,500 –15,000 hospitalizations and 100 –150 deaths every year. 2– 6 Although the risk of severe disease was higher in adults, children bore the brunt of the health burden with 90% of varicella cases, 67% of the varicella hospitalizations and one-half the varicella deaths occurring in this age group. 2– 4 It was recognition of this health burden and the knowledge that children were the primary transmitters of infection that led the United States to adopt a program of universal vaccination of children in 1995. Germany is the only country in Europe with routine childhood immunization. Varicella vaccine was incorporated into the routine immunization schedule in July 2004, as a