Varicella disease after introduction of varicella vaccine in the United States, 1995-2000

Effectiveness of post-exposure prophylaxis during varicella outbreaks among primary and middle school students in Shanghai: An analysis of three-year surveillance data

OBJECTIVES

To evaluate the effectiveness of post-exposure prophylaxis conducted during varicella outbreaks among students in Shanghai.

METHODS

Surveillance data were collected from September 1, 2013 to December 31, 2016 involving 3524 susceptible students in 109 primary and middle school classes where emergency vaccinations (EVs) had been administered. Students were divided into two groups according to their prior vaccination (PV) varicella vaccine status. A secondary attack rate was used to compare EV and non-EV groups using a chi-squared test. Stratification analyses were performed, adjusting for the EV administration date, the vaccination coverage rate, and the number of cases prior to the EV.

RESULTS

The effectiveness rate was 92.2% (95% confidence interval (CI): 37.1-99.0%) when EV was applied within 3 days following the outbreak onset date, and 95.2% (95% CI: 79.9-98.8%) when vaccination coverage was ≥80% among students with PV. When students with PV received an EV for varicella within 3 days, the effectiveness rate was 100%.

CONCLUSIONS

EV showed high protective effectiveness for varicella during outbreaks, especially if administered within 3 days of an outbreak and in conjunction with a high coverage rate.

Congenital Viral Infection: Traversing the Uterine-Placental Interface

Why certain viruses cross the physical barrier of the human placenta but others do not is incompletely understood. Over the past 20 years, we have gained deeper knowledge of intrauterine infection and routes of viral transmission. This review focuses on human viruses that replicate in the placenta, infect the fetus, and cause birth defects, including rubella virus, varicella-zoster virus, parvovirus B19, human cytomegalovirus (CMV), Zika virus (ZIKV), and hepatitis E virus type 1. Detailed discussions include ( a) the architecture of the uterine-placental interface, ( b) studies of placental explants ex vivo that provide insights into the infection and spread of CMV and ZIKV to the fetal compartment and how these viruses undermine early development, and ( c) novel treatments and vaccines that limit viral replication and have the potential to reduce dissemination, vertical transmission and the occurrence of congenital disease.

Varicella infections in patients with end stage renal disease: a systematic review

BACKGROUND

End stage renal disease (ESRD) is on the rise globally. Varicella infection among adult patients with ESRD has been reported to lead to multiple complications and even death. While varicella vaccination has been recommended in paediatric renal patients; recommendation on varicella vaccination among adult patients with ESRD remained sparse. This review is aimed at evaluating the impact of varicella infection among adult patients with ESRD and make a recommendation for vaccination.

METHODS

Three databases (PubMed, Embase and Cumulative Index to Nursing and Allied Health Literature (CINAHL)) were searched in April 2018 with keywords 'varicella, chronic kidney failure, chronic kidney disease, renal replacement therapy, kidney transplantation, end stage renal disease, end stage renal failure, chicken pox, vaccine, vaccination and complications'.

RESULTS

29 articles were selected for review. The studies were mainly case reports, and they included measured outcomes: prevalence of seronegativity, impact (morbidity, length of stay, and mortality) of varicella among patients with ESRD, seroconversion rates and safety of varicella vaccination. The prevalence of seronegativity among varicella-infected ESRD adults was found to be at 42 to 100%. Nineteen deaths were reported. At least 54 patients have had complications from varicella infection. Seroconversion rate post vaccination was found to be around 64-94%.

CONCLUSION

Varicella is associated with significant morbidity and mortality rates in adult patients with ESRD. Varicella vaccination should be considered for the vulnerable, seronegative patients.

[Decrease in the incidence of chickenpox in the Community of Madrid after universal childhood immunization. Years 2001-2015]

OBJECTIVE

Varicella vaccine was recommended in the Community of Madrid (CM) at 15months of age between November 2006 and December 2013. The objective was to describe the impact of vaccination on the incidence of varicella in the CM during the period 2001-2015.

DESIGN

A descriptive study of cases of varicella reported to the Sentinel Physician Network of the CM and the cases recorded in the Minimum Basic Data Set at hospital discharge was carried out. Total incidence of cases and of hospital admissions were calculated, as well as specific incidence by age and sex.

RESULTS

The incidence was 94.0% lower between 2012 and 2013 than between 2001 and 2003. Between 2014 and 2015 the incidence was 61.8% higher than between 2012 and 2013. The highest incidence was observed in children aged 0 to 4years except for 2010-2014, which was exceeded by the incidence in children aged 5 to 9. The trend in hospital admissions was also decreasing, with the highest incidence in children aged 0 to 1year, followed by 1-4years.

CONCLUSIONS

There has been a significant decrease in the incidence of cases and of hospital admissions by varicella in all age groups after the recommendation to vaccinate at 15months of age, which is compatible with the effectiveness of a dose and its ability to produce immunity group. The withdrawal of this recommendation between 2014 and 2015 has led to an increase in the incidence.

Analysis of the Protective Immunity Induced by Herpes Simplex Virus 1 Strain M3 with an Attenuated Phenotype Due to Mutations in the Viral ul7, ul41, and LAT Genes

Herpes simplex virus 1 (HSV1) is an important pathogen with a worldwide epidemic trend that affects populations of various ages. It has a high morbidity, particularly in juveniles, but a successful HSV1 vaccine is not currently available. Thus, our study systematically observed the immune responses induced in mice immunized with the attenuated HSV1 M3 mutant strain, which has mutations in the genes encoding the UL7 and Vhs tegument proteins and the latency-associated transcript. The immunity induced by the M3 mutant strain can control acute viral infection during HSV1 wild-type strain infection. Moreover, this immunity exerts a potent effect on controlling viral entry into the trigeminal neurons. These data encourage further studies investigating the development of M3 as a potential vaccine candidate, and much work is necessary to evaluate the safety and improve the immunogenicity of this strain.

Varicella infection in a non-universally vaccinated population: Actual epidemiology in Bulgaria (2013-2015)

BACKGROUND

Varicella is a common and usually mild disease but it has great importance in regard to general infectious morbidity. The current study aimed to characterize possible risk factors of varicella epidemiology in Bulgaria, a country where infection follows its natural epidemiological pattern as no mandatory or recommended vaccine is currently applied.

METHODS

Administrative regions of Bulgaria were used as units of observation and a set of sociodemographic and economic determinants, as well as geographic location (south or north) were tested for associations with the mean 3-year varicella incidence rates (2013-2015).

RESULTS

The proportion of urban population, proportion of females, number of health care units and proportion of urban population aged <10 years were the four sociodemographic variables most strongly and significantly correlated (p<0.05) with varicella frequency (Spearman's rank correlation coefficients of 0.62, 0.47, 0.43, and 0.38, respectively). After reducing the number of intercorrelated factors to a few principal components and accounting for confounders, the demographic component and geographic location remained most robustly associated with varicella incidence in Bulgaria (adjusted R² of 0.51, p<0.001).

CONCLUSIONS

The results obtained identify important determinants in the local epidemiology of varicella and show that community characteristics should be considered, to improve our understanding of varicella distribution.

[Clinical, epidemiological and etiological studies of adult aseptic meningitis: Report of 11 cases with varicella zoster virus meningitis]

We treated 11 cases (52.7 ± 14.9 years, all male) with varicella zoster virus (VZV) meningitis and 437 cases with adult aseptic meningitis from 2004 to 2016. The incidence rate of adult VZV meningitis in the cases with aseptic meningitis was 2.5%. Herpes zoster infections are reported to have occurred frequently in summer and autumn. VZV meningitis also occurred frequently in the similar seasons, in our patients. The diagnoses were confirmed in 9 cases with positive VZV-DNA in the cerebrospinal fluid and in 2 cases with high VZV-IgG indexes (> 2.0). For diagnosis confirmation, the former test was useful for cases within a week of disease onset, and the latter index was useful for cases after a week of disease onset. Zoster preceded the meningitis in 8 cases, while the meningitis preceded zoster in 1 case, and 2 cases did not have zoster (zoster sine herpete). Two patients were carriers of the hepatitis B virus, 1 patient was administered an influenza vaccine 4 days before the onset of meningitis, and 1 patient was orally administered prednisolone for 2 years, for treatment. Their immunological activities might have been suppressed. The neurological complications included trigeminal neuralgia, facial palsy (Ramsay Hunt syndrome), glossopharyngeal neuralgia, and Elsberg syndrome. Because the diseases in some patients can become severe, they require careful treatment.

Evaluating the effectiveness of the universal immunization program against varicella in Japanese children

OBJECTIVE

Matched case control study was conducted to elucidate the effectiveness of the Oka/Biken vaccine immediately after implementation of the universal immunization program in Japan.

METHODS

Cases were laboratory confirmed varicella patient under 15years of age diagnosed at 14 designated pediatric clinics between September 2015 and September 2016. Controls were selected from patients who visited the same practice for different reasons as the varicella case within 2weeks. Swab samples were collected from varicella suspected patients and molecular diagnostic assays were used to confirm varicella cases. Matched odds ratio were used to calculate vaccine effectiveness (VE).

RESULTS

Varicella zoster virus DNA was detected in 183 (81.3%) of 225 suspected cases. One sample was excluded because it was positive for the Oka vaccine strain (182/225, 80.9%). Three hundred twenty-three control subjects were enrolled. The effectiveness of 1 dose of the Oka/Biken vaccine compared with no vaccine was 76.7% (95% confidence interval [CI]: 58.6-86.9%; P<0.001). The effectiveness of 2 doses of the Oka/Biken vaccine was 94.2% (95% CI: 85.7-97.6%; P<0.001). After adjusting for potential confounding effects, the adjusted VE of 1 and 2 doses of varicella vaccine were 76.9% (95% CI: 58.1-87.3%; P<0.001) and 94.7% (95% CI: 86.0-98.0%; P<0.001), respectively.

CONCLUSIONS

VE of one dose of Oka/Biken varicella vaccine was insufficient to control varicella. Therefore, two doses of Oka/Biken varicella vaccine is significant for controlling varicella in Japan.

Preparing to introduce the varicella vaccine into the Italian immunisation programme: varicella-related hospitalisations in Tuscany, 2004-2012

A universal immunisation programme against varicella in the form of the measles-mumps-rubella-varicella (MMRV) vaccine for toddlers aged 13-15 months was introduced in Tuscany in July 2008. An assessment of the impact of this programme on varicella-related hospitalisations 4 years after its introduction could further support its adoption at a national level. The hospitalisation data were analysed in two periods: pre-vaccination (2004-2007) and vaccination period (2009-2012). The high coverage of the vaccines (84% in 2012) resulted in a significant decline in notifications, from 33,114 (2004-2007) to 13,184 cases (2009-2012), and also of hospitalisations, from 584 (pre-vaccination period) to 325 (vaccination period). The hospitalisation rate was 4.1 per 100,000 (95% confidence intervals (CI): 3.4-4.7) before the introduction of vaccination, which dropped to 2.2 per 100,000 (95% CI: 1.7-2.7) in the vaccination period (hospitalisation risk ratios: 0.54; 95% CI:  0.472-0.619). The reduction was most significant in the youngest age groups. The introduction of universal vaccination has already led to a significant decline in hospitalisations due to varicella after just 4 years of implementation. Hospitalisation rates fell noticeably among younger individuals involved in the vaccination programme. The decrease in hospitalisation rate in the older age groups suggests a possible indirect protection.

Safety of Second-Dose Single-Antigen Varicella Vaccine

BACKGROUND AND OBJECTIVE

In 2006, routine 2-dose varicella vaccination for children was recommended to improve control of varicella. We assessed the safety of second-dose varicella vaccination.

METHODS

We identified second-dose single-antigen varicella vaccine reports in the Vaccine Adverse Event Reporting System during 2006 to 2014 among children aged 4 to 18 years. We analyzed reports by age group (4-6 and 7-18 years), sex, serious or nonserious status, most common adverse events (AEs), and whether other vaccines were administered concomitantly with varicella vaccine. We reviewed serious reports of selected AEs and conducted empirical Bayesian data mining to detect disproportional reporting of AEs.

RESULTS

We identified 14 641 Vaccine Adverse Event Reporting System reports after second-dose varicella vaccination, with 494 (3%) classified as serious. Among nonserious reports, injection site reactions were most common (48% of children aged 4-6 years, 38% of children aged 7-18 years). The most common AEs among serious reports were pyrexia (31%) for children aged 4 to 6 years and headache (28%) and vomiting (27%) for children aged 7 to 18 years. Serious reports of selected AEs included anaphylaxis (83), meningitis (5), encephalitis (16), cellulitis (52), varicella (6), herpes zoster (6), and deaths (7). One immunosuppressed adolescent was reported with vaccine-strain herpes zoster. Only previously known AEs were reported more frequently after second-dose varicella vaccination compared with other vaccines.

CONCLUSIONS

We identified no new or unexpected safety concerns for second-dose varicella vaccination. Robust safety monitoring remains an important component of the national varicella vaccination program.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Microbiology laboratory and the management of mother-child varicella-zoster virus infection

Varicella-zoster virus, which is responsible for varicella (chickenpox) and herpes zoster (shingles), is ubiquitous and causes an acute infection among children, especially those aged less than six years. As 90% of adults have had varicella in childhood, it is unusual to encounter an infected pregnant woman but, if the disease does appear, it can lead to complications for both the mother and fetus or newborn. The major maternal complications include pneumonia, which can lead to death if not treated. If the virus passes to the fetus, congenital varicella syndrome, neonatal varicella (particularly serious if maternal rash appears in the days immediately before or after childbirth) or herpes zoster in the early years of life may occur depending on the time of infection. A Microbiology laboratory can help in the diagnosis and management of mother-child infection at four main times: (1) when a pregnant woman has been exposed to varicella or herpes zoster, a prompt search for specific antibodies can determine whether she is susceptible to, or protected against infection; (2) when a pregnant woman develops clinical symptoms consistent with varicella, the diagnosis is usually clinical, but a laboratory can be crucial if the symptoms are doubtful or otherwise unclear (atypical patterns in immunocompromised subjects, patients with post-vaccination varicella, or subjects who have received immunoglobulins), or if there is a need for a differential diagnosis between varicella and other types of dermatoses with vesicle formation; (3) when a prenatal diagnosis of uterine infection is required in order to detect cases of congenital varicella syndrome after the onset of varicella in the mother; and (4) when the baby is born and it is necessary to confirm a diagnosis of varicella (and its complications), make a differential diagnosis between varicella and other diseases with similar symptoms, or confirm a causal relationship between maternal varicella and malformations in a newborn.

A double blind, randomized, active controlled study to assess the safety, tolerability and immunogenicity of measles, mumps rubella, and varicella vaccine (MMRV) manufactured using an alternative process

Vaccination against measles, mumps, rubella, and varicella is recommended for all children in the US. Limitations manufacturing Oka/Merck strain varicella-zoster virus have hampered the availability of the combination vaccine (MMRV) against these 4 viruses, which drove the need to investigate an alternative manufacturing process. Healthy children 12-to-23 months of age at 71 US sites were randomized (1:1) to receive MMRV manufactured using an alternative process (MMRVAMP) or the currently licensed MMRV. Subjects received 2 0.5 mL doses 3 months apart. Sera were collected before and 6 weeks after Dose-1. Adverse experiences (AEs) were collected for 42 d after each dose and serious AEs and events of special interest for 180 d after Dose-2. Overall, 706 subjects were randomized to MMRVAMP and 706 to MMRV and 698 and 702 received at least 1 dose of study vaccine, respectively. The risk difference in response rates and geometric mean concentrations of antibody to measles, mumps, rubella, and varicella viruses 6 weeks after Dose-1 met non-inferiority criteria for MMRVAMP versus, MMRV. Response rates met acceptability criteria for each virus, and the seroconversion rate to varicella-zoster virus was 99.5% in both groups. Vaccine-related AEs were mostly mild-to-moderate in intensity and somewhat more common after MMRVAMP. Febrile seizures occurred at similar rates in both groups during the first 42 d after each vaccine dose. MMRVAMP is non-inferior to MMRV and represents an important advancement in maintaining an adequate supply of vaccines against these diseases.

Digital epidemiology reveals global childhood disease seasonality and the effects of immunization

Public health surveillance systems are important for tracking disease dynamics. In recent years, social and real-time digital data sources have provided new means of studying disease transmission. Such affordable and accessible data have the potential to offer new insights into disease epidemiology at national and international scales. We used the extensive information repository Google Trends to examine the digital epidemiology of a common childhood disease, chicken pox, caused by varicella zoster virus (VZV), over an 11-y period. We (i) report robust seasonal information-seeking behavior for chicken pox using Google data from 36 countries, (ii) validate Google data using clinical chicken pox cases, (iii) demonstrate that Google data can be used to identify recurrent seasonal outbreaks and forecast their magnitude and seasonal timing, and (iv) reveal that VZV immunization significantly dampened seasonal cycles in information-seeking behavior. Our findings provide strong evidence that VZV transmission is seasonal and that seasonal peaks show remarkable latitudinal variation. We attribute the dampened seasonal cycles in chicken pox information-seeking behavior to VZV vaccine-induced reduction of seasonal transmission. These data and the methodological approaches provide a way to track the global burden of childhood disease and illustrate population-level effects of immunization. The global latitudinal patterns in outbreak seasonality could direct future studies of environmental and physiological drivers of disease transmission.

Immunisation led to a major reduction in paediatric patients hospitalised because of the varicella infection in Israel

AIM

The varicella-zoster virus causes infections that are often mild but can cause substantial morbidity and mortality in otherwise healthy children. We examined trends in varicella-related hospitalisations before and after the implementation of a national two-dose varicella vaccination programme in Israel in September 2008.

METHODS

This retrospective chart review, performed at three tertiary care paediatric hospitals in greater Tel Aviv, compared data from 2004 to 2008 and 2009 to 2012, before and after the varicella programme was launched. It included all children to the age of 18 who were hospitalised for conditions associated with the varicella infection.

RESULTS

After the vaccination programme was introduced, the number of children hospitalised for varicella fell by 63% (p < 0.5), from 38.9 to 14.5 per 10 000, and there was a 75% reduction in children aged one to six. During the same period, the percentage of hospitalised children who were immunocompromised rose from 9.7% to 18.4% (p < 0.05). The most common complications were soft-tissue infections (60%), and the most prevalent pathogens were Group A β-haemolytic streptococcus (53%) and Staphylococcus aureus (32%).

CONCLUSION

The introduction of a two-dose immunisation programme dramatically decreased the varicella burden in Israel, leading to a major reduction in hospitalisation admissions linked to the infection.

Varicella Vaccine Effectiveness in Preventing Community Transmission in the 2-Dose Era

OBJECTIVES

We examined overall and incremental effectiveness of 2-dose varicella vaccination in preventing community transmission of varicella among children aged 4 to 18 years in 2 active surveillance sites. One-dose varicella vaccine effectiveness (VE) was examined in those aged 1 to 18 years.

METHODS

From May 2009 through June 2011, varicella cases identified during active surveillance in Antelope Valley, CA and Philadelphia, PA were enrolled into a matched case-control study. Matched controls within 2 years of the patient's age were selected from immunization registries. A standardized questionnaire was administered to participants' parents, and varicella vaccination history was obtained from health care provider, immunization registry, or parent records. We used conditional logistic regression to estimate varicella VE against clinically diagnosed and laboratory-confirmed varicella.

RESULTS

A total of 125 clinically diagnosed varicella cases and 408 matched controls were enrolled. Twenty-nine cases were laboratory confirmed. One-dose VE (1-dose versus unvaccinated) was 75.6% (95% confidence interval [CI], 38.7%-90.3%) in preventing any clinically diagnosed varicella and 78.1% (95% CI, 12.7%-94.5%) against moderate or severe, clinically diagnosed disease (≥50 lesions). Among subjects aged ≥4 years, 2-dose VE (2-dose versus unvaccinated) was 93.6% (95% CI, 75.6%-98.3%) against any varicella and 97.9% (95% CI, 83.0%-99.7%) against moderate or severe varicella. Incremental effectiveness (2-dose versus 1-dose) was 87.5% against clinically diagnosed varicella and 97.3% against laboratory-confirmed varicella.

CONCLUSIONS

Two-dose varicella vaccination offered better protection against varicella from community transmission among school-aged children compared with 1-dose vaccination.

Global Varicella Vaccine Effectiveness: A Meta-analysis

CONTEXT

Several varicella vaccines are available worldwide. Countries with a varicella vaccination program use 1- or 2-dose schedules.

OBJECTIVE

We examined postlicensure estimates of varicella vaccine effectiveness (VE) among healthy children.

DATA SOURCES

Systematic review and descriptive and meta-analysis of Medline, Embase, Cochrane libraries, and CINAHL databases for reports published during 1995-2014.

STUDY SELECTION

Publications that reported original data on dose-specific varicella VE among immunocompetent children.

DATA EXTRACTION

We used random effects meta-analysis models to obtain pooled one dose VE estimates by disease severity (all varicella and moderate/severe varicella). Within each severity category, we assessed pooled VE by vaccine and by study design. We used descriptive statistics to summarize 1-dose VE against severe disease. For 2-dose VE, we calculated pooled estimates against all varicella and by study design.

RESULTS

The pooled 1-dose VE was 81% (95% confidence interval [CI]: 78%-84%) against all varicella and 98% (95% CI: 97%-99%) against moderate/severe varicella with no significant association between VE and vaccine type or study design (P > .1). For 1 dose, median VE for prevention of severe disease was 100% (mean = 99.4%). The pooled 2-dose VE against all varicella was 92% (95% CI: 88%-95%), with similar estimates by study design.

LIMITATIONS

VE was assessed primarily during outbreak investigations and using clinically diagnosed varicella.

CONCLUSIONS

One dose of varicella vaccine was moderately effective in preventing all varicella and highly effective in preventing moderate/severe varicella, with no differences by vaccine. The second dose adds improved protection against all varicella.

Diagnosis, antiviral therapy, and prophylaxis of varicella-zoster virus infections

Varicella-zoster virus (VZV), an important member of the Herpesviridae family, is the etiological agent of varicella as primary infection and zoster as recurrence. An outstanding feature is the lifelong viral latency in dorsal root and cranial nerve ganglia. Both varicella and zoster are worldwide widespread diseases that may be associated with significant complications. However, there is a broad spectrum of laboratory methods to diagnose VZV infections. In contrast to many other viral infections, antiviral treatment of VZV infections and their prevention by vaccination or passive immunoprophylaxis are well established in medical practice. The present manuscript provides an overview about the basic knowledge of VZV infections, their laboratory diagnosis, antiviral therapy, and the prevention procedures, especially in Germany.

Efficacy of varicella (VZV) vaccination: an update for the clinician

Varicella-zoster virus (VZV) infection causes two distinct clinical conditions. Primary varicella infection results in chickenpox, a contagious rash illness typically seen among children. VZV can reactivate years after the initial infection to cause herpes zoster (HZ) and lead to post-herpetic neuralgia, a common complication resulting in persistent pain that may last for years after the zoster rash resolves. A person's risk of having longer lasting and more severe pain associated with HZ increases with age. Since the introduction of VZV vaccines, the rates of infection, hospitalizations, and mortality have declined. In this review, we discuss in detail current VZV vaccines available for the prevention of VZV and HZ infections. Varilrix (GSK Biologicals, UK), Varivax (Merck, USA) and the combined measles, mumps, rubella, and varicella (MMRV) vaccine contain the live attenuated Oka strain of VZV for routine varicella vaccination. While Zostavax is the only HZ vaccine currently approved for use in the United States and the European Union [EMEA, 2011], a subunit vaccine candidate called HZ/su has recently shown improved efficacy for zoster prevention in two clinical trial phase III studies. VariZIG, a post-exposure prophylactic, uses zoster immune globulin to prevent VZV infection in those who have recently been in contact with VZV but lack evidence of varicella immunity and are contraindicated to receive the varicella vaccine. Further, we discuss the skin tropic and neurotropic factor VZV ORF7 gene and its involvement in varicella infection, reactivation and latency in ganglia. Ultimately, these studies can contribute to the development of a neuroattenuated vaccine candidate against varicella or a vector for delivery of other virus antigens.

Varicella paediatric hospitalisations in Belgium: a 1-year national survey

BACKGROUND

Varicella universal vaccination (UV) has been implemented in many countries for several years. Nevertheless, varicella UV remains debated in Europe and few data are available on the real burden of infection. We assessed the burden of varicella in Belgium through analysis of hospitalised cases during a 1-year period.

METHODS

Data on children admitted to hospital with varicella were collected through a national network from November 2011 to October 2012. Inclusion criteria were either acute varicella or related complications up to 3 weeks after the rash.

RESULTS

Participation of 101 hospitals was obtained, covering 97.7% of the total paediatric beds in Belgium. 552 children were included with a median age of 2.1 years. Incidence of paediatric varicella hospitalisations reached 29.5/10(5) person-years, with the highest impact among those 0-4 years old (global incidence and odds of hospitalisation: 79/10(5) person-years and 1.6/100 varicella cases, respectively). Only 14% (79/552) of the cohort had an underlying chronic condition. 65% (357/552) of children had ≥1 complication justifying their admission, 49% were bacterial superinfections and 10% neurological disorders. Only a quarter of children (141/552) received acyclovir. Incidence of complicated hospitalised cases was 19/10(5) person-years. Paediatric intensive care unit admission and surgery were required in 4% and 3% of hospitalised cases, respectively. Mortality among Belgian paediatric population was 0.5/10(6) and fatality ratio 0.2% among our cohort.

CONCLUSIONS

Varicella demonstrated a substantial burden of disease in Belgian children, especially among the youngest. Our thorough nationwide study, run in a country without varicella UV, offers data to support varicella UV in Belgium.

Antibody induced by one-dose varicella vaccine soon became weak in children: evidence from a cross-sectional seroepidemiological survey in Beijing, PRC

BACKGROUND

Numerous post-licensure studies, mostly from field epidemiological evidences such as outbreak surveys, have demonstrated the effectivenesss and insufficiency of one-dose varicella vaccine in outbreak control. Serological evidence of immunization failure is, however, relatively less reported in contrast. A cross-sectional seroepidemiological survey of Beijing residents was performed in 2012 in the People's Republic of China, after the one-dose varicella vaccine had been widely used for several years.

METHODS

Multistage stratified random sampling method was designed to recruit 2 144 subjects. The ELISA method was used to test the present blood samples collected and the reserve samples collected in 2008 to assess the trends of anti-VZV seroprevalence in the past 5 years and to determine the risk factors for varicella infection.

RESULTS

The age- and sex- adjusted overall anti-VZV seropositivity of Beijing residents in 2012 was 84.5%. Two groups' adjusted overall anti-VZV seroprevalence in 2012 showed obvious growth compared with 2008 (<1 yr old: from 6.3% to 16.9%; 1-4 yr old: from 27.6% to 57.2%). Reported one-dose vaccination history was 71.6% (149/208), 80.9% (182/225) and 82.2% (180/219) in the 1-4 yr, 5-9 yr, 10-14 yr age groups, respectively. Of subjects who had received the one-dose vaccine, 36% (216/603) showed negative anti-VZV concentrations (<110 mIU/mL); additionally 15.9% (96/603) of such subjects' anti-VZV concentrations were in the lowest positive concentration group (110-299 mIU/mL). Seropositivity in permanent residents of 1-9 yr old with verified vaccination was merely 61.8%. Various age groups (1-3 yr, 4-6 yr, and 7-9 yr) all showed seropositivity that gradually decreased with increasing of the interval between vaccination and blood sampling.

CONCLUSION

Mass varicella vaccination significantly improved the immunity of younger Beijing residents. However, vaccine-induced anti-VZV antibody soon became weak in children with high coverage (approximately 80%) after vaccination for several years which is significantly higher than reported in pre-licensure studies. A government-funded 2-dose immunization program with mandatory vaccination schedule for Beijing residents may need consideration in the near future.

The impact of demographic changes on the epidemiology of herpes zoster: Spain as a case study

Varicella zoster virus (VZV) causes varicella upon first exposure and may reactivate later in life into herpes zoster (HZ), with a risk that is thought to be reduced by re-exposures to VZV. Given the decades-long time scales of reactivation and its dependence on the accumulation of re-exposure episodes, adopting a long-term perspective may be useful to correctly interpret current epidemiological trends of VZV. In this study, we investigate the possible impact of demographic changes on varicella and HZ in Spain, using an age-structured mathematical model informed with historical demographic data and calibrated against age-specific profiles of varicella seroprevalence and HZ incidence data. The model qualitatively reproduces the remarkable growth of HZ incidence observed in Spain between 1997 and 2004, before the introduction of varicella vaccination programmes. We demonstrate that this growth may be partially ascribed to the reduction of varicella circulation that followed the overall decline of the birth rate in the twentieth century. Model predictions further suggest that, even under the most optimistic projections, HZ incidence will continue its rise until at least 2040. Considering the effect of demographic changes can help interpreting variations in epidemiological trends of HZ, contributing to a more accurate evaluation of vaccination programmes against VZV.

Continuing Decline in Varicella Incidence After the 2-Dose Vaccination Recommendation-Connecticut, 2009-2014

Background. Varicella is a highly contagious vaccine-preventable illness. In 1996, the Advisory Committee for Immunization Practices recommended 1 dose of vaccine for children, and in 2006 it recommended 2 doses; Connecticut required 1 dose for school entry in 2000 and 2 doses for school entry starting in 2011. Connecticut varicella incidence overall and among persons aged 1–14 years declined during 2005–2008. We analyzed varicella surveillance data for 2009–2014 to characterize overall and age group-specific trends in the setting of the 2-dose requirement.

Methods. Passive surveillance was used to collect data and identify incidence trends and changes in proportions, and these were assessed by χ² tests for trend and proportion, respectively.

Results. Varicella incidence decreased from 13.8 cases/100 000 persons during 2009 to 5.1 cases/100 000 persons during 2014 (P < .001); significant declines in incidence occurred among children aged 1–4, 5–9, and 10–14 years (P < .01 for each age group). Cases classified as preventable decreased from 44% during 2009 to 25% during 2014 (P < .01); significant declines in percentages of preventable cases occurred only among those aged 5–9 years (P < .05) and 10–14 (P < .01) years.

Conclusions. Varicella incidence continued to decline in Connecticut in the setting of the 2-dose school-entry program. Continued surveillance is needed to assess the full influence of the 2-dose recommendation.

A spot of bother: Why varicella vaccine programs matter

Objective

To evaluate Ontario's provincial varicella vaccination program through analysis of aggregate varicella cases in order to determine whether there has been a decrease in reportable disease burden; and to assess varicella vaccine adverse events following immunization (AEFIs).

Methods

Aggregate varicella cases (1993-2013) were extracted from the reportable disease databases. Pre-program (1993-2004) and post-program (2007-2013) periods were chosen according to implementation of the publicly funded vaccination program. AEFIs following administration of varicella vaccines (2010-2013) were also extracted. Reporting rates were calculated using net doses distributed as the denominator. Serious AEFIs were defined using World Health Organization standards.

Results

The incidence of aggregate varicella reports decreased significantly over the study period (from 311.4 to 22.2 cases per 100,000 population in 1993 and 2013, respectively). Incidence also decreased significantly in all age groups between the pre- and the post-program periods with a shift in age distribution towards older individuals in the post-program period. A total of 162 AEFIs following varicella vaccine were reported between 2010 and 2013 for an annualized reporting rate of 14.6 per 100,000 doses distributed. The most common events were rash (37.3%), including eight reports of varicella-like rash (0.7 per 100,000 doses distributed). Ten serious events were reported (0.9 per 100,000 doses distributed), and all vaccine recipients recovered.

Conclusion

Significant reductions in varicella disease incidence and low AEFI reporting rates were observed with the introduction of the publicly funded varicella vaccine program in Ontario. Continued surveillance is indicated to further assess trends in varicella disease and vaccine safety.

Varicella zoster virus infection

Infection with varicella zoster virus (VZV) causes varicella (chickenpox), which can be severe in immunocompromised individuals, infants and adults. Primary infection is followed by latency in ganglionic neurons. During this period, no virus particles are produced and no obvious neuronal damage occurs. Reactivation of the virus leads to virus replication, which causes zoster (shingles) in tissues innervated by the involved neurons, inflammation and cell death - a process that can lead to persistent radicular pain (postherpetic neuralgia). The pathogenesis of postherpetic neuralgia is unknown and it is difficult to treat. Furthermore, other zoster complications can develop, including myelitis, cranial nerve palsies, meningitis, stroke (vasculopathy), retinitis, and gastroenterological infections such as ulcers, pancreatitis and hepatitis. VZV is the only human herpesvirus for which highly effective vaccines are available. After varicella or vaccination, both wild-type and vaccine-type VZV establish latency, and long-term immunity to varicella develops. However, immunity does not protect against reactivation. Thus, two vaccines are used: one to prevent varicella and one to prevent zoster. In this Primer we discuss the pathogenesis, diagnosis, treatment, and prevention of VZV infections, with an emphasis on the molecular events that regulate these diseases. For an illustrated summary of this Primer, visit: http://go.nature.com/14xVI1.

Systematic review of models assessing the economic value of routine varicella and herpes zoster vaccination in high-income countries

BACKGROUND

A systematic review was conducted to assess the cost-effectiveness of routine varicella and herpes zoster (HZ) vaccination in high-income countries estimated by modelling studies.

METHODS

A PubMed search was performed to identify relevant studies published before October 2013. Studies were included in the review if they (i) evaluated the cost-effectiveness of routine childhood or adolescent varicella vaccination and/or HZ vaccination targeting the elderly, and if they (ii) reported results for high-income countries.

RESULTS

A total of 38 model-based studies were identified that fulfilled the inclusion criteria. Routine childhood or adolescent varicella vaccination was cost-effective or cost-saving from a payer perspective and always cost-saving from a societal perspective when ignoring its potential impact on HZ incidence due to reduced or absent exogenous boosting. The inclusion of the potential impact of childhood varicella vaccination on HZ led to net quality-adjusted life-year (QALY) losses or incremental cost-effectiveness ratios exceeding commonly accepted thresholds. Additional HZ vaccination could partially mitigate this effect. Studies focusing only on the evaluation of HZ vaccination reported a wide range of results depending on the selected target age-group and the vaccine price, but most found HZ vaccination to be a cost-effective or marginally cost-effective intervention. Cost-effectiveness of HZ vaccination was strongly dependent on the age at vaccination, the price of the vaccine, the assumed duration of protection and the applied cost per QALY threshold.

CONCLUSIONS

While HZ vaccination is mostly considered cost-effective, cost-effectiveness of varicella vaccination primarily depends on the in- or exclusion of exogenous boosting in the model. As a consequence, clarification on the role of exogenous boosting is crucial for decision-making regarding varicella vaccination.

A monoclonal antibody-based VZV glycoprotein E quantitative assay and its application on antigen quantitation in VZV vaccine

Varicella-zoster virus (VZV) is a highly infectious agent that causes varicella and herpes zoster (HZ), which may be associated with severe neuralgia. Vaccination is the most effective way to reduce the burden of the diseases. VZV glycoprotein E (gE) is the major and most immunogenic membrane protein that plays important roles in vaccine efficacy. A quantitative assay for gE content is desirable for the VZV vaccine process monitoring and product analysis. In this study, 70 monoclonal antibodies (mAbs) were obtained after immunizing mice with purified recombinant gE (rgE). The collection of mAbs was well-characterized, and a pair of high-affinity neutralization antibodies (capture mAb 4A2 and detection mAb 4H10) was selected to establish a specific and sensitive sandwich enzyme-linked immunosorbent assay (ELISA) to quantify the native and recombinant gE. The detection limit of this assay was found to be 1.95 ng/mL. Furthermore, a reasonably good correlation between the gE content (as measured by the mAb-based quantitative ELISA) and the virus titer (as measured by the "gold standard" plaque assay) was observed when both assays were performed for tracking the kinetics of virus growth during cell culture. A total of 16 batches of lyophilized VZV vaccine were tested using the newly developed quantitative ELISA and classical plaque assay, demonstrating reasonably good correlation between gE content and virus titer. Therefore, this mAb-based gE quantitative assay serves as a rapid, stable, and sensitive method for monitoring viral antigen content, one additional quantitative method for VZV vaccine process and product characterization. This quantitative ELISA may also serve as a complementary method for virus titering.

Burden of varicella in Italy, 2001-2010: analysis of data from multiple sources and assessment of universal vaccination impact in three pilot regions

Varicella represents the most widespread vaccine-preventable childhood infectious disease in Italy. The purpose of this retrospective study was to assess the burden of varicella in Italy and in three regions that first implemented universal varicella vaccination. Four data sources were analysed: statutory notification data, the National Hospital Discharge Database, mortality data, and the vaccination coverage reached in Sicilia, Veneto and Apulia. The incidence rates per 100,000 population were calculated using the Italian resident population provided by the Italian Institute of Statistics in 2001-2010. In 2001-2010, the mean annual incidence of notifications of varicella was 150.7 cases per 100,000 population, reaching 948.6 cases per 100,000 population in the paediatric age group. The annual incidence declined to 102.6 per 100,000 population in 2010. During the period considered, 20,295 hospitalizations for varicella were observed. The mean annual incidence was 3.4 per 100,000 population, reaching a minimum of 2.5 per 100,000 in 2009 and 2010. Of the hospitalizations, 68.4% occurred in the paediatric age group. The median length of hospital stay was 4 days. During 2001-2003 and 2006-2010, 33 deaths were reported. In the three regions considered, vaccination coverage increased steadily, reaching 81.5% in Sicily, 79.4% in Veneto and 75.6% in Apulia in 2010. During the same period, hospitalization and notification rates decreased significantly. This study demonstrated that varicella continues to represent a relevant health problem in Italy, especially in the paediatric age group. Data obtained from the three Italian regions that first introduced universal vaccination demonstrated that vaccination reduces the incidence of varicella and hospitalization rates.

The role of temperature in reported chickenpox cases from 2000 to 2011 in Japan

Annual periodicities of reported chickenpox cases have been observed in several countries. Of these, Japan has reported a two-peaked, bimodal annual cycle of reported chickenpox cases. This study investigated the possible underlying association of the bimodal cycle observed in the surveillance data of reported chickenpox cases with the meteorological factors of temperature, relative humidity and rainfall. A time-series analysis consisting of the maximum entropy method spectral analysis and the least squares method was applied to the chickenpox data and meteorological data of 47 prefectures in Japan. In all of the power spectral densities for the 47 prefectures, the spectral lines were observed at the frequency positions corresponding to the 1-year and 6-month cycles. The optimum least squares fitting (LSF) curves calculated with the 1-year and 6-month cycles explained the underlying variation of the chickenpox data. The LSF curves reproduced the bimodal and unimodal cycles that were clearly observed in northern and southern Japan, respectively. The data suggest that the second peaks in the bimodal cycles in the reported chickenpox cases in Japan occurred at a temperature of approximately 8·5 °C.

An evaluation of voluntary 2-dose varicella vaccination coverage in New York City public schools

OBJECTIVES

We assessed coverage for 2-dose varicella vaccination, which is not required for school entry, among New York City public school students and examined characteristics associated with receipt of 2 doses.

METHODS

We measured receipt of either at least 1 or 2 doses of varicella vaccine among students aged 4 years and older in a sample of 336 public schools (n = 223 864 students) during the 2010 to 2011 school year. Data came from merged student vaccination records from 2 administrative data systems. We conducted multivariable regression to assess associations of age, gender, race/ethnicity, and school location with 2-dose prevalence.

RESULTS

Coverage with at least 1 varicella dose was 96.2% (95% confidence interval [CI] = 96.2%, 96.3%); coverage with at least 2 doses was 64.8% (95% CI = 64.6%, 64.9%). Increasing student age, non-Hispanic White race/ethnicity, and attendance at school in Staten Island were associated with lower 2-dose coverage.

CONCLUSIONS

A 2-dose varicella vaccine requirement for school entry would likely improve 2-dose coverage, eliminate coverage disparities, and prevent disease.

Varicella vaccination programs do not seem to shift the age of disease to older age groups

The paper of Baxter et al., recently published in Pediatrics show through five cross-sectional studies, a high impact of vaccination in the decline of varicella incidence and hospitalizations in all age groups in the United States between 1995 and 2009. As a consequence of herd immunity, varicella incidence has also diminished in those non vaccinated, which indicates no shift in the burden of varicella to older age groups.

Central nervous system complications of varicella-zoster virus

OBJECTIVE

To describe the spectrum of central nervous system complications of varicella-zoster virus (VZV) in children admitted to The Hospital for Sick Children between January 1999 and December 2012.

STUDY DESIGN

Children aged 1 month to 18 years (n = 84) admitted with neurologic manifestations associated with a characteristic VZV rash or a confirmatory laboratory test (positive lesion scraping or cerebrospinal fluid polymerase chain reaction) were included in the study. Acute neurologic complications were included if they occurred within 4 weeks of VZV infection. Stroke was considered related to VZV if it occurred within 6 months of VZV infection, the neuroimaging was characteristic, and other causes were excluded.

RESULTS

Clinical syndromes included acute cerebellar ataxia (n = 26), encephalitis (n = 17), isolated seizures (n = 16), stroke (n = 10), meningitis (n = 10), Guillain-Barré syndrome (n = 2), acute disseminated encephalomyelitis (n = 2), and Ramsay Hunt syndrome (n = 1). In those with acute complications (nonstroke), neurologic symptoms occurred a median of 5 days after rash onset (range -6 to +16). The time between rash onset and stroke ranged from 2 weeks to 26 weeks (median 16.0 weeks). Three children with encephalitis died. Residual neurologic sequelae at one year occurred in 9 of 39 (23%) of children with follow-up data. Only 4 children were reported to have received the varicella vaccine.

CONCLUSION

Neurologic complications of VZV infection continue to occur despite the availability of an effective vaccine. Neurologic symptom onset can predate the appearance of the VZV exanthem and in rare cases may occur in the absence of an exanthem.

Varicella hospitalizations in Los Angeles during the varicella vaccination era, 2003-2011: are they preventable?

Characteristics of varicella-related hospitalizations in the mature varicella vaccination era, including the proportion vaccinated and the severity of disease, are not well described. We present the vaccination status, severity and reasons for hospitalization of the hospitalized varicella cases reported to the Los Angeles County Health Department from 2003 to 2011, the period which includes the last 4 years of the mature one-dose program and the first 5 years after introduction of the routine two-dose program. A total of 158 hospitalized varicella cases were reported overall, of which 52.5% were potentially preventable and eligible for vaccination, 41.8% were not eligible for vaccination, and 5.7% were vaccinated. Most hospitalizations (72.2%) occurred among healthy persons, 54.4% occurred among persons ≥20 years of age, and 3.8% of hospitalizations resulted in death. Our data suggest that as many as half of the hospitalized varicella cases, including half of the deaths, may have been preventable given that they occurred in persons who were eligible for vaccination. More complete implementation of the routine varicella vaccination program could further reduce the disease burden of severe varicella.

Impact of vaccination on the epidemiology of varicella: 1995-2009

BACKGROUND

When varicella vaccine was licensed in the United States in 1995, there were concerns that childhood vaccination might increase the number of adolescents susceptible to varicella and shift disease toward older age groups where it can be more severe.

METHODS

We conducted a series of 5 cross-sectional studies in 1994 to 1995 (prevaccine), 2000, 2003, 2006, and 2009 in Kaiser Permanente of Northern California to assess changes in varicella epidemiology in children and adolescents, as well as changes in varicella hospitalization in people of all ages. For each study, information on varicella history and varicella occurrence during the past year was obtained by telephone survey from a sample of ∼8000 members 5 to 19 years old; varicella hospitalization rates were calculated for the entire membership.

RESULTS

Between 1995 and 2009, the overall incidence of varicella in 5- to 19-year-olds decreased from 25.8 to 1.3 per 1000 person-years, a ∼90% to 95% decline in the various age categories (5-9, 10-14, and 15-19 years of age). The proportion of varicella-susceptible children and adolescents also decreased in all age groups, including in 15- to 19-year-olds (from 15.6% in 1995 to 7.6% in 2009). From 1994 to 2009, age-adjusted varicella hospitalization rates in the general member population decreased from 2.13 to 0.25 per 100,000, a ∼90% decline.

CONCLUSIONS

In the 15 years after the introduction of varicella vaccine, a major reduction in varicella incidence and hospitalization was observed with no evidence of a shift in the burden of varicella to older age groups.

Successes and challenges in varicella vaccine

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 HZ incidence increase. Possible reasons for not observing the predicted increase in HZ incidence are explored. The advantages and disadvantages of universal vs targeted vaccination as well as different vaccination schedules are discussed.

The epidemiology of varicella cases among children in Beijing's Fengtai District from 2008 to 2012

In recent years, the number of breakthrough cases of varicella (onset >42 days after vaccination) increased each year, and varicella outbreaks continue to occur in Beijing. Data from the Immunization Information System and the Infectious Disease Reporting System demonstrated that in Beijing's Fengtai District, the varicella breakthrough rate increased from 0.7% in 2008 to 2.5% in 2012 and showed an increased trend (P<0.001). Among the varicella cases in children (age of 3-15 years), the number of breakthrough cases increased from 167 in 2008 to 622 in 2012, which was 45.2% (n=1735) of the total child cases (n=3842). From 2008 to 2012, a total of 62 outbreaks occurred; among the 787 affected child outbreak cases, 61% were vaccinated. Altogether, the results from this study indicated that 1-dose vaccination cannot sufficiently prevent the occurrence of breakthrough cases of varicella or control varicella outbreaks in Beijing's Fengtai District.

Varicella outbreak in a daycare: challenges and opportunities for preventing varicella outbreaks in this setting

As a result of single-dose varicella vaccination, daycare outbreaks have become rare. We investigated a daycare outbreak resulting from a misdiagnosed varicella case in an unvaccinated attendee. Of 25 attendees aged 12-32 months without evidence of immunity, 7 (28%) were unvaccinated due to religious/philosophical opposition or recent 1st birthday. Single-dose vaccination reduced disease by 92% compared with no vaccination.

Live vaccine use and safety in DiGeorge syndrome

OBJECTIVE

Live vaccines are generally contraindicated in patients with DiGeorge syndrome (DGS), a congenital disorder characterized by cellular immune deficiency. Vaccine utilization and safety in this population are not well described. This study examined vaccination patterns and adverse events following live immunization (AEFLI) in these individuals.

METHODS

A multicenter retrospective cohort study was conducted in subjects with DGS confirmed by fluorescence in situ hybridization assay (chromosome 22q11.2 microdeletion). Live vaccine-preventable illnesses, vaccination coverage and timeliness, and AEFLIs in the 56-day window after live vaccination were examined. Bivariate and multivariable analyses assessed the impact of demographics medical history, timing of diagnostic confirmation, and preceding immune function on vaccination patterns and AEFLIs.

RESULTS

Of 194 subjects, 77% and 75% received measles-mumps-rubella (MMR) and varicella vaccines, respectively; 58% completed recommended vaccinations by age 19 to 35 months. Adverse events occurred after 14% and 20% of MMR and varicella vaccine doses, respectively. Most events were minor, few were serious, and no deaths were reported in post-live vaccination windows. Although early diagnostic confirmation negatively affected live vaccination coverage and timeliness (P < .001), baseline CD4% did not differ between subjects who did or did not receive live vaccines by 12 to 18 months. Among varicella vaccine recipients, those with a subsequent adverse event had a lower preceding CD4% (24.8% ± 7.3%) than those without (35.5% ± 11.7%) (P < .05); no CD4% differences were observed with MMR vaccination. Fourteen unvaccinated subjects experienced live vaccine-preventable illnesses.

CONCLUSIONS

Live vaccines were frequently given and generally well-tolerated among patients with DGS with mild-to-moderate immunosuppression.

Varicella-zoster vaccine in the USA: success for control of disease severity, but what next?

In the period from 1990 to 1994, before the introduction of a varicella vaccine to the USA, approximately 100 deaths in otherwise healthy individuals, children and adolescents under 20 years of age, were attributable to varicella complications. The administration of a single-dose vaccine has now been widespread in the USA for nearly 10 years; however, since the effectiveness of a single dose in children under 13 years of age in an outbreak situation is approximately 80%, consideration of a second booster dose is in progress although not yet recommended. Licensure of a measles-mumps-rubella-varicella vaccine may hasten the recommendation.

Successes and remaining challenges after 10 years of varicella vaccination in the USA

Beginning in 1995, universal varicella vaccination was recommended in the USA for all children aged 12-18 months, and all susceptible adolescents and adults. Many physicians were initially sceptical about the need to prevent primary varicella. However, with passage of state daycare and school entry mandates for varicella immunization, national varicella vaccination rates increased to approximately 90% by 2004. Several studies have demonstrated concomitant reductions in varicella-related healthcare utilization, costs and varicella-related mortality among children in the vaccinated age group, as well as adults. Remaining challenges include: first, outbreaks of 'breakthrough' varicella in vaccinated populations, which may prompt a second-dose recommendation, and second, possible increases in the incidence of secondary varicella (zoster) among adults whose natural immunity may wane in the absence of endemic varicella. The latter concern highlights the importance of a promising new varicella vaccine for older adults that may be licensed and recommended in the next 2 years.

Comparing Active and Passive Varicella Surveillance in Philadelphia, 2005–2010: Recommendations for the Transition to Nationwide Passive Varicella Disease Surveillance

Objective.

The Philadelphia Department of Public Health (PDPH) conducts active surveillance for varicella in West Philadelphia. For its approximately 300 active surveillance sites, PDPH mandates biweekly reports of varicella (including zero cases) and performs intensive case investigations. Elsewhere in Philadelphia, surveillance sites passively report varicella cases, and abbreviated investigations are conducted. We used active varicella surveillance program data to inform the transition to nationwide passive varicella surveillance.

Methods.

We compared classification of reported cases, varicella disease incidence, and reporting completeness for active and passive surveillance areas for 2005–2010. We assessed reporting completeness using capture-recapture analysis of 2- to 18-year-old cases reported by schools/daycare centers and health-care providers.

Results.

From 2005 to 2010, PDPH received 3,280 passive and 969 active surveillance varicella case reports. Most passive surveillance reports were classified as probable cases (18% confirmed, 56% probable, and 26% excluded), whereas nearly all of the active surveillance reports were either confirmed or excluded (36% confirmed, 11% probable, and 53% excluded). Overall incidence rates calculated using confirmed/probable cases were similar in the active and passive surveillance areas. Detection of laboratory-confirmed, breakthrough, and moderate-to-severe cases was equivalent for both surveillance areas.

Conclusions.

Although active surveillance for varicella results in better classified cases, passive surveillance provides comparable data for monitoring disease trends in breakthrough and moderate-to-severe varicella. To further improve passive surveillance in the two-dose-varicella vaccine era, jurisdictions should consider conducting periodic enhanced surveillance, encouraging laboratory testing, and collecting additional varicella-specific variables for passive surveillance.

Different vaccination strategies in Spain and its impact on severe varicella and zoster

Varicella vaccines available in Spain were marketed in 1998 and 2003 for non-routine use. Since 2006 some regions decided to include varicella vaccination in their regional routine vaccination programmes at 15-18 months of age. Other regions chose the strategy of vaccinating susceptible adolescents. This study shows the trends in severe varicella zoster virus infections through the analysis of the hospital discharges related to varicella and herpes zoster in the general population from 2005 to 2010 in Spain. A total of 11,125 hospital discharges related to varicella and 27,736 related to herpes zoster were reported during the study period. The overall annual rate of hospitalization was 4.14 cases per 100,000 for varicella and 10.33 cases per 100,000 for herpes zoster. In children younger than 5 years old varicella hospitalization rate significantly decreased from 46.77 in 2005 to 26.55 per 100,000 in 2010. The hospitalization rate related to herpes zoster slightly increased from 9.71 in 2005 to 10.90 per 100,000 in 2010. This increase was mainly due to the significant increase occurring in the >84 age group, from 69.55 to 97.68 per 100,000. When gathering for regions taking into account varicella vaccine strategy, varicella related hospitalizations decreased significantly more in those regions which included the vaccine at 15-18 months of age as a routine vaccine comparing with those vaccinating at 10-14 years old. No significant differences were found in herpes zoster hospitalization rates regarding the varicella vaccination strategy among regions. Severe varicella infections decreased after implementation of varicella vaccination in Spain. This decrease was significantly higher in regions including the vaccine at 15-18 months of age compared with those vaccinating susceptible adolescents.