Varicella-related hospitalizations in the vaccine era

Global Prevalence of Varicella-Associated Complications: A Systematic Review and Meta-Analysis

INTRODUCTION

Varicella (chickenpox) is an infectious disease caused by the varicella zoster virus affecting children, adolescents, and adults. Varicella symptoms are usually self-limiting; however, different complications with widespread and systemic manifestations can occur. This systematic literature review aims to explore and quantify varicella-associated complication rates.

METHODS

Two databases (Embase and MEDLINE), congress abstracts, and reference lists of systematic reviews were screened to identify evidence on varicella complications. Complications were identified and grouped into 14 clinically relevant categories. Proportional meta-analyses were conducted using a random-effects model and tests for heterogeneity and publication bias were performed. Subgroup, sensitivity, and meta-regression analyses were also conducted. A total of 78 studies, spanning 30 countries, were included in the meta-analysis.

RESULTS

Pooled prevalence was highest in severe varicella (22.42%; 95% confidence interval [CI] 10.13-37.77), skin-related complications (20.12%; 95% CI 15.48-25.20), and infection-related complications (10.03%; 95% CI 7.47-12.90). Cardiovascular (0.55%; 95% CI 0.08-1.33), genitourinary (1.17%; 95% CI 0.55-1.99), and musculoskeletal (1.54%; 95% CI 1.06-2.11) complications had the lowest pooled prevalence. The remaining complication categories ranged between 1% and 10%. Subgroup analysis showed that complications were more prevalent in children versus adults and in hospitalized patients versus outpatients. Meta-regression analysis found that no ecological level covariates were accurate predictors for the overall prevalence of varicella-associated complications. There was substantial heterogeneity and publication bias across all meta-analyses.

CONCLUSION

Results suggest that different types of varicella-associated complications could be frequent, impacting quality of life, and healthcare resource utilisation and budgets. These findings are crucial to raise awareness of the health and economic burden of varicella disease.

Impact of the tetra viral vaccine introduction on varicella morbidity and mortality in the Brazilian macro regions

OBJECTIVE

To describe the impact of the introduction of the viral tetra vaccine in the National Immunization Program in 2013 for 15-month-old children in mortality rates and hospitalization associated with varicella in Brazil.

METHODS

Mortality rates and hospitalizations rates associated with varicella were evaluated between 2010 and 2016 and described according to Brazilian macro regions and age. The population was stratified into age groups: < 1year, 1-4 years, and 5-14 years. Data were collected from the Informatics Department of the Unified Health System. A percentage difference was calculated between rates of hospitalizations and mortality in the pre (2010-2012) and post-vaccination periods (2014-2016) to estimate the approximate effectiveness of the vaccine.

DATA SYNTHESIS

At the national level, vaccination significantly reduced the mortality rates and hospitalizations rates in all age groups analyzed. Among those under 5 years of age, mortality rates and hospitalizations rates decreased 57-49% and 40-47%, respectively. There was a national decrease of up to 57% in the mortality rates due to the disease, with smaller decreases seen in the North and Northeast regions and the largest in the South and Southeast regions. The hospitalizations rates for varicella reached a maximum national decline of 47%. In children aged 1-4 years, with higher vaccination coverage, the highest reduction was observed in both mortality rates and hospitalizations rates, which decreased from 2.6 to 0.4/100,000/year.

CONCLUSIONS

The tetra vaccine proved to be effective in reducing both mortality and hospitalizations of children and adolescents up to 15 years of age in the 2014-2016 triennium.

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.

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.

Incidence and use of resources for chickenpox and herpes zoster in Latin America and the Caribbean--a systematic review and meta-analysis

BACKGROUND

Varicella-zoster virus causes chickenpox and herpes zoster. More than 90% of varicella cases occur in childhood. The aim of this study was to gather all relevant information on epidemiology and resource use in Latin America and the Caribbean since 2000.

METHODS

Epidemiologic studies published since 2000 with at least 50 cases of varicella or herpes zoster, or at least 10 cases of congenital disease were included. Gray literature was also searched. Outcomes included incidence, admission rate, mortality and case-fatality ratio. Use of resources and both direct and indirect costs associated were extracted.

RESULTS

From the 495 records identified, 23 were included in the meta-analysis to report varicella-zoster virus outcomes and 3 in the herpes zoster analysis. The global pooled varicella incidence in subjects under 15 years of age was 42.9 cases per 1000 individuals per year (95% confidence interval: 26.9-58.9); children under 5 years of age were the most affected. Pooled general admission rate was 3.5 per 100,000 population (95% confidence interval: 2.9-4.1) and median hospitalization was 5-9 days. The most common varicella complications reported in studies were skin infections (3-61%), followed by respiratory infections (0-15%) and neurologic problems (1-5%). Direct costs averaged (2011/international dollar [I$]) $2040 per admission (range, I$ 298-5369) and I$70 per clinical visit (range, 11-188 I$).

CONCLUSIONS

Limited information was available on the outcomes studied. Improvements in the surveillance of ambulatory cases are required to obtain a better epidemiologic picture. As of 2011, only 2 countries introduced the vaccine in national immunization programs in Latin America and the Caribbean.

The effect of funded varicella immunization programs on varicella-related hospitalizations in IMPACT centers, Canada, 2000-2008

BACKGROUND

The 12 Immunization Monitoring Program, Active (IMPACT) centers that represent 90% of pediatric tertiary care beds in Canada conducted active surveillance for varicella-related hospitalizations and complications from 1999 onward, after varicella vaccine was authorized. Publicly funded routine immunization programs at 12 or 15 months of age were introduced by 5 provinces and territories (prov/terr) in 2000 to 2002 (earlier programs, EP) and by 8 prov/terr in 2004 to 2007 (later programs, LP).

OBJECTIVE

To determine whether the number of varicella-related hospitalized cases had declined by 2008 at 12 IMPACT centers after the sequential introduction of publicly funded varicella immunization programs in Canada.

METHODS

Varicella-related hospitalizations from 2000 to 2008 in the prov/terr with EP were under surveillance by 3 IMPACT centers (Halifax, Edmonton, Calgary), whereas the prov/terr with LP were under surveillance by the remaining 9 centers. The age, gender, underlying health status, varicella complications, and length of stay in hospital and the pediatric intensive care unit were documented. Breakthrough cases were identified and their clinical characteristics described.

RESULTS

Between 2000 and 2008, the number of varicella-related hospitalized cases in IMPACT centers declined relatively sooner in prov/terr with EP (by 2002 to 2003), as compared to those with LP (only by 2007 to 2008). In 2008, varicella-related hospitalized cases declined by 88% in the EP centers, and by 81% in the LP centers. In all IMPACT centers, the greatest decline occurred in the 1-4 years age group (90% decline), with smaller declines in both <1 year and 5-9 years age groups (78% and 76% decline, respectively). Breakthrough disease accounted for 39 (2%) cases, with the proportion due to breakthrough increasing from 0.9% in 2000 to 2001, to 2% in 2003 to 2004 and 9.5% in 2007 to 2008. The majority (72%) of breakthrough cases were in immunocompromised children.

CONCLUSIONS

Publicly funded varicella vaccination programs have led to a significant decline in varicella-related hospitalizations in Canadian children, as a result of direct effects of the program beginning within 1 to 2 years after the start, as well as probable indirect protection of children outside the vaccinated cohort.

Varicella breakthrough infection and vaccine effectiveness in Taiwan

We performed this nationwide retrospective investigation among the recipients of varicella vaccine to evaluate the breakthrough varicella infection rate, factors associated with breakthrough infection and the vaccine effectiveness. The recipients of these vaccinations were identified through Taiwan's National Immunization Information System and data on breakthrough infections among these recipients were collected by using Taiwan's National Health Insurance Claims Database. From 2000 to 2007, 1,057,345 persons received varicella vaccinations in Taiwan. Varicella breakthrough infection occurred among 22,640 (2.1%) vaccinees and 170 (0.016%) required hospitalization for varicella disease. Annual breakthrough infection rates ranged from 0.12% to 2.04%. The mean age of vaccination was 1.6 years (median 1.3 years) and the mean age at breakthrough infection was 3.9 years. The mean interval between vaccination and the breakthrough infection was 2.3 years. The rate was significantly lower in regions where free varicella vaccinations were available than in regions where they were not (P<0.001). Varicella breakthrough infection was significantly more likely to occur at 5 and 6 years of age among the vaccinees, who received vaccination between 12 months and 23 months of age (P<0.001). The vaccine effectiveness against varicella was 82.6% and against varicella-related hospitalization was 85.4% from 2000 to 2005.

Varicella-related hospitalizations in the United States, 2000-2006: the 1-dose varicella vaccination era

OBJECTIVE

To describe the effect of the mature 1-dose varicella vaccination program on varicella morbidity, we analyzed 2 national databases for varicella-related hospitalizations in the United States since implementation of the varicella vaccination program in 1995.

PATIENTS AND METHODS

Data from the National Hospital Discharge Survey and Nationwide Inpatient Sample were analyzed to describe trends in varicella-related hospitalizations during the 1-dose vaccination era (2000-2006) compared with those in the prevaccination era (1988-1995). Varicella-related hospitalizations were defined by using International Classification of Diseases, Ninth Revision codes. Results were extrapolated to represent national estimates.

RESULTS

Using National Hospital Discharge Survey data, 24,488 varicella-related hospitalizations were estimated to occur in the United States during the 1-dose vaccination era. The varicella-related hospitalization rate was 0.12 per 10,000 population during the 1-dose vaccination era versus 0.42 per 10,000 population in the prevaccination era (P < .01). During the 1-dose vaccination era, the estimated annual average number of varicella-related hospitalizations was significantly lower and decreased by ≥ 65% in all age groups compared with those in the prevaccination era (P < .001 in all age groups). The varicella-related hospitalization rate during the 1-dose vaccination era estimated from the Nationwide Inpatient Sample was 0.09 per 10,000 population.

CONCLUSIONS

Varicella-related hospitalization numbers and rates declined significantly during the 1-dose varicella vaccination era. Assuming declines in varicella-related hospitalizations are due, mainly, to the routine childhood varicella vaccination program, these data suggest that varicella vaccination prevented ∼ 50,000 varicella-related hospitalizations in the United States from 2000 to 2006.

Decline in varicella-related ambulatory visits and hospitalizations in the United States since routine immunization against varicella

BACKGROUND

Widespread varicella vaccination has led to substantial decreases in varicella-related mortality and hospitalizations. The effect of the vaccine on ambulatory care utilization is poorly defined.

OBJECTIVE

To determine trends in varicella-related ambulatory care and hospital discharges before and after vaccine licensure.

DESIGN, SETTING, AND PARTICIPANTS

Estimates of varicella-related ambulatory and hospital discharges were calculated for the pre- (1993-1995) and post- (1996-2004) vaccine licensure periods using the National Ambulatory Medical Care Survey, National Hospital Ambulatory Medical Care Survey, and National Hospital Discharge Survey.

MAIN OUTCOME MEASURE

Ambulatory and hospital discharge rates for varicella.

RESULTS

The rate of varicella-related ambulatory discharges decreased by 66% from 106.6 per 100,000 (95% confidence interval [CI]: 80.5-132.6) in the prelicensure period to 36.4 per 100,000 population (95% CI: 29.3-43.5) in the post-licensure period (P < 0.001). The decrease was significant across all age groups <45 years, with the greatest reduction (98%) occurring among patients 0 to 4 years of age. The incidence of varicella-related hospital discharges decreased by 53% from 30.9 per 100,000 (95% CI: 24.4-37.3) to 14.5 per 100,000 population (95% CI: 12.1-16.8; P < 0.001). This difference was significant among patients <14 years of age. Rates of varicella-related ambulatory discharges decreased significantly for both whites and non-whites in the postlicensure period, but postlicensure ambulatory discharge rates remained higher for non-whites than for whites. Decreases in varicella-related hospital discharges were statistically significant for whites and non-whites. Racial differences in the incidence of varicella-related hospital discharges also persisted following vaccine licensure.

CONCLUSIONS

Varicella-related ambulatory visits and hospitalizations have decreased significantly in the period after licensure of the varicella vaccine.

Impact of varicella vaccine on varicella-zoster virus dynamics

The licensure and recommendation of varicella vaccine in the mid-1990s in the United States have led to dramatic declines in varicella incidence and varicella-related deaths and hospitalizations. Varicella outbreaks remain common and occur increasingly in highly vaccinated populations. Breakthrough varicella in vaccinated individuals is characteristically mild, typically with fewer lesions that frequently do not progress to a vesicular stage. As such, the laboratory diagnosis of varicella has grown increasingly important, particularly in outbreak settings. In this review the impact of varicella vaccine on varicella-zoster virus (VZV) disease, arising complications in the effective diagnosis and monitoring of VZV transmission, and the relative strengths and limitations of currently available laboratory diagnostic techniques are all addressed. Since disease symptoms often resolve in outbreak settings before suitable test specimens can be obtained, the need to develop new diagnostic approaches that rely on alternative patient samples is also discussed.

Intravenous immunoglobulin in children with streptococcal toxic shock syndrome

BACKGROUND

Streptococcal toxic shock syndrome (TSS) is a rare and severe manifestation of group A streptococcal infection. The role of intravenous immunoglobulin (IVIG) for streptococcal TSS in children is controversial. This study aims to describe the epidemiology of streptococcal TSS in children and to determine whether adjunctive therapy with IVIG is associated with improved outcomes.

METHODS

A multicenter, retrospective cohort study of children with streptococcal TSS from 1 January 2003 through 31 December 2007 was conducted. Propensity scores were used to determine each child's likelihood of receiving IVIG. Differences in the primary outcomes of death, hospital length of stay, and total hospital costs were compared after matching IVIG recipients and nonrecipients on propensity score.

RESULTS

The median patient age was 8.2 years. IVIG was administered to 84 (44%) of 192 patients. The overall mortality rate was 4.2% (95% confidence interval, 1.8%-8.0%). Differences in mortality between IVIG recipients (n = 3; 4.5%) and nonrecipients (n = 3; 4.5%) were not statistically significant (p > .99). Although patients receiving IVIG had higher total hospital and drug costs than nonrecipients, differences in hospital costs were not significant once drug costs were removed (median difference between matched patients, $6139; interquartile range, -$8316 to $25,993; P = .06). No differences were found in length of hospital stay between matched IVIG recipients and nonrecipients.

CONCLUSION

This multicenter study is, to our knowledge, the largest to describe the epidemiology and outcomes of children with streptococcal TSS and the first to explore the association between IVIG use and clinical outcomes. IVIG use was associated with increased costs of caring for children with streptococcal TSS but was not associated with improved outcomes.

Varicella prevention in the United States: a review of successes and challenges

OBJECTIVE

In 1995, the United States was the first country to introduce a universal 1-dose childhood varicella vaccination program. In 2006, the US varicella vaccine policy was changed to a routine 2-dose childhood program, with catchup vaccination for older children. The objective of this review was to summarize the US experience with the 1-dose varicella vaccination program, present the evidence considered for the policy change, and outline future challenges of the program.

METHODS

We conducted a review of publications identified by searching PubMed for the terms "varicella," "varicella vaccine," and "herpes zoster." The search was limited to US publications except for herpes zoster; we reviewed all published literature on herpes zoster incidence.

RESULTS

A single dose of varicella vaccine was 80% to 85% effective in preventing disease of any severity and >95% effective in preventing severe varicella and had an excellent safety profile. The vaccination program reduced disease incidence by 57% to 90%, hospitalizations by 75% to 88%, deaths by >74%, and direct inpatient and outpatient medical expenditures by 74%. The decline of cases plateaued between 2003 and 2006, and outbreaks continued to occur, even among highly vaccinated school populations. Compared with children who received 1 dose, in 1 clinical trial, 2-dose vaccine recipients developed in a larger proportion antibody titers that were more likely to protect against breakthrough disease and had a 3.3-fold lower risk for breakthrough disease and higher vaccine efficacy. Two studies showed no increase in overall herpes zoster incidence, whereas 2 others showed an increase.

CONCLUSIONS

A decade of varicella prevention in the United States has resulted in a dramatic decline in disease; however, even with high vaccination coverage, the effectiveness of 1 dose of vaccine did not generate sufficient population immunity to prevent community transmission. A 2-dose varicella vaccine schedule, therefore, was recommended for children in 2006. Data are inconclusive regarding an effect of the varicella vaccination program on herpes zoster epidemiology.

The burden of varicella complications before the introduction of routine varicella vaccination in Germany

BACKGROUND

The true burden of varicella complications in Germany is not known. We investigated the incidence and pattern of varicella complications in children and adolescents using 3 independent surveillance sources.

METHODS

Prospective nationwide surveillance in all pediatric hospitals through the German Pediatric Surveillance Unit [Erhebungseinheit für Seltene Pädiatrische Erkrankungen in Deutschland (ESPED)] was used to ascertain hospitalized varicella cases in children <or=16 years of age between January 2003 and December 2004. In the federal state, North-Rhine Westphalia (NRW), a practice sentinel network [European Diabetes Study Group (EURODIAB)] and pediatric hospital based International Statistical Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) surveillance were additionally used to refine incidence estimates via capture-recapture methodology.

RESULTS

A total of 918 hospitalized varicella patients (male-to-female: 55%/45%) with a median age of 3.3 years (interquartile range, 1.4-5.2) and a median hospital stay of 5 days (interquartile range, 3-8) were reported. Varicella associated complications occurred in 80% of the hospitalizations, most frequently being neurologic (25.4%), skin infectious (23.2%), and gastrointestinal tract complications (15.0%). Most hospitalizations (77%) occurred in previously healthy children. A predisposing condition existed in 207 children (23%): immunosuppression 7%, atopic dermatitis 7%, and other underlying chronic conditions 9%. Severity of varicella complications was related to increasing age and immunosuppression. Permanent or possible sequelae were reported in 15 (1.7%) and 78 (8.7%) of all children, respectively; 10 children died. Capture-recapture analyses yielded an incidence of 14.1 (95% confidence interval, 9.7-18.6) varicella hospitalizations/100,000 children, corresponding to 1996 (95% confidence interval, 1363-2629) varicella-related hospitalizations per year in Germany.

CONCLUSIONS

These data show that the severity of varicella complications in healthy children has been previously underestimated.

Should the UK introduce varicella vaccine?

Perspective on the paper by Cameron et al (see page 1062)

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.

Immunogenicity of Oka/Merck varicella vaccine in children vaccinated at 12-14 months of age versus 15-23 months of age

OBJECTIVE

Recent reports suggest that breakthrough varicella may be more common in children when the Oka/Merck varicella vaccine is given at 12-14 months of age than when it is given at older ages. An analysis of 5 postlicensure clinical trials with this vaccine was conducted to evaluate immune response relative to the age of the vaccine recipient.

METHODS

In 5 clinical trials, 3771 children, 12 through 23 months of age with no history of varicella, received an injection of varicella vaccine. Varicella-zoster virus (VZV) antibody was measured 6 weeks postvaccination by glycoprotein enzyme-linked immunosorbent assay (gpELISA), an assay that correlates with neutralizing antibody. Endpoints evaluated were the response rate (percent of subjects with VZV antibody > or =5 gpELISA units/mL, a titer shown to correlate with protection) and geometric mean titer (GMT) of VZV antibody. Each endpoint was compared across 3 age groups (12-14, 15-17, and 18-23 months of age). Response rates by initial VZV serostatus were evaluated for children vaccinated at 12-14 months of age to assess whether maternal antibody had an impact on the immune response.

RESULTS

The response rates were similar among 12-14, 15-17, and 18-23 month olds (93.8, 90.8, and 93.1%, respectively); GMTs were significantly higher among the 12-14 month olds (15.1, 13.5, and 13.7 gpELISA units/mL, respectively). Among children 12-14 months of age, response rates and GMTs were similar regardless of their prevaccination VZV serostatus.

CONCLUSIONS

Oka/Merck varicella vaccine is highly immunogenic when given to children 12-14 months of age. The immunogenicity profile is similar to that of children 15-17 and 18-23 months of age. The presence of low titers of VZV antibody before vaccination did not influence vaccine response in 12-14 month olds. These results support current recommendations for universal varicella vaccination beginning at 12 months of age.

Varicella

Varicella-zoster virus, a herpesvirus, causes varicella (chickenpox) and, after endogenous reactivation, herpes zoster (shingles). Varicella, which is recognised by a characteristic vesicular rash, arises mainly in young children, although older individuals can be affected. In immunocompetent patients, symptoms are usually mild to moderate, but an uncomplicated severe case can have more than 1000 lesions and severe constitutional symptoms. Serious complications--including central nervous system involvement, pneumonia, secondary bacterial infections, and death--are sometimes seen. Varicella can be prevented by vaccination. Vaccine is about 80-85% effective against all disease and highly (more than 95%) effective in prevention of severe disease. In the USA, a routine childhood immunisation programme has reduced disease incidence, complications, hospital admissions, and deaths in children and in the general population, indicating strong herd immunity. Similar immunisation programmes have been adopted by some other countries, including Uruguay, Germany, Taiwan, Canada, and Australia, and are expected to be implemented more widely in future.

Varicella-related hospitalization and emergency department visit rates, before and after introduction of varicella vaccine, among white and black children in Hamilton County, Ohio

OBJECTIVE

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.

STUDY DESIGN

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.

RESULTS

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.

CONCLUSIONS

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.

Chickenpox complications in Saudi Arabia: Is it time for routine varicella vaccination?

INTRODUCTION

Varicella zoster (chickenpox) infection is a common and benign disease of childhood. The predominance of uncomplicated cases in children tends to overshadow the morbidity associated with severe cases and the resultant hospitalization.

OBJECTIVE

The objective was to establish the complication rate of chickenpox in the Saudi National Guard population over a 2(1/2)-year period.

METHODS

All reported cases of chickenpox at the King Abdulaziz Medical City, Riyadh were prospectively followed for development of complications during the period between 1 June 2001 and 30 December 2003.

RESULTS

A total of 3802 cases of chickenpox were reported and followed during the acute illness phase. The majority of cases, 2984 (78%), occurred in children less than 15 years of age. Among all chickenpox cases, 78 (2%) required hospitalization, and 50 patients developed 58 (1.5%) complications. Skin and soft tissue infections were the most common complications, 20 (34%), followed by pneumonia in 16 (28%), bacteremia in six (10%), encephalitis in four (7%) and necrotizing fasciitis in four (7%). Complications were less common in children (36/2984, 1.2%) as compared to adults (14/818, 1.7%) (p = 0.26). However, pneumonia (p = 0.03) and hospitalization (p = 0.004) were more common in adults as compared to children. The overall fatality rate was 0.05%; two patients died, one aged two months the other 28 years.

CONCLUSION

These data provide a baseline for morbidity and mortality from chickenpox, and further support the inclusion of varicella vaccine in the routine childhood immunization program in Saudi Arabia.

Decline in varicella-related hospitalizations and expenditures for children and adults after introduction of varicella vaccine in the United States

OBJECTIVE

Universal childhood immunization against varicella in the United States, first recommended in 1995, was predicted to lead to significant decreases in varicella-related hospitalization rates and corresponding charges. Previous studies have not found such effects. We studied trends in varicella-related hospitalization rates and associated charges before and after introduction of varicella vaccine.

METHODS

We examined hospitalization and charge data from the Nationwide Inpatient Sample for the years 1993-2001, representative of national hospitalization patterns for children and adults. We derived weighted estimates of population-adjusted, varicella-related hospitalization rates and inflation-adjusted, varicella-related hospital charges.

RESULTS

The annual varicella-related hospitalization rate exceeded 0.5 hospitalizations per 10,000 US population from 1993 to 1995, declined to 0.26 per 10,000 by 1999, and again halved to 0.13 per 10,000 by 2001. Hospitalization rates declined most substantially among individuals primarily targeted for vaccination (0- to 4-year-old children) but decreased among youths aged 5 to 19 years and among adults as well. Concomitantly, varicella-related hospital charges declined from 161.1 million dollars (95% confidence interval: 130.5 million dollars-191.8 million dollars) in 1993 to 66.3 million dollars (95% confidence interval: 50.9 million dollars-81.7 million dollars) in 2001 (all 2001 US dollars). Among expected primary payers, inflation-adjusted declines in varicella-related hospital discharges-related charges accrued to Medicaid, private insurance, and "other" payers (including uninsured and self-pay) but not to Medicare.

CONCLUSIONS

This national analysis indicates a clinically and statistically significant reduction in varicella-related hospitalizations for children and adults associated with childhood varicella immunization in the United States and a corresponding significant decrease in hospital charges.

Reduction in pediatric hospitalizations for varicella-related invasive group A streptococcal infections in the varicella vaccine era

OBJECTIVES

To assess changes in hospitalization rates for invasive group A streptococcal (IGAS) and varicella-associated IGAS (VA-IGAS) infections at a pediatric hospital over a period of 9 years, to characterize clinical features of patients with IGAS infections, and to assess frequency of macrolide-resistant IGAS isolates. Study design Medical records of all hospitalized patients with group A streptococcus isolated from a normally sterile site from 1993 to 2001 were reviewed. Data collected included demographics, clinical course, microbiologic features, outcome, and presence of streptococcal toxic shock syndrome (STSS) or necrotizing fasciitis (NF). Annual hospitalization rates for IGAS were determined.

RESULTS

There were 144 patients with IGAS infections, including 11 (8%) with STSS or NF. Overall mortality rate was 2% (3/144) but 18% (2/11) among patients with STSS or NF. Preexisting varicella was present in 16% (23/144); 4 of 23 VA-IGAS cases had STSS or NF. Although there was no change in annual hospitalization rates for IGAS infections during the study period, the percentage of VA-IGAS hospitalizations decreased from 27% in the prevaccine era (1993 to 1995), to 16% during vaccine implementation (1996 to 1998) and 2% during widespread vaccine use (1999 to 2001) (linear-by-linear association, P=.001). Macrolide resistance was low in 1993 to 1995 (5%, 1/19) and 1996 to 1998 (0%, 0/42) among tested IGAS isolates and increased significantly in 1999 to 2001 (13%, 5/38) (Fisher exact, P=.035).

CONCLUSIONS

A decline in pediatric varicella-related IGAS hospitalizations was temporally associated with utilization of varicella vaccine. These data reinforce the importance of universal varicella vaccination for children. Increasing macrolide resistance among IGAS isolates indicates a need for continued surveillance.