Neonatal varicella

Neonatal varicella is mostly caused by maternal chickenpox acquired during the last 3 weeks of pregnancy. Transplacentally transmitted infections occur in the first 10 to 12 days of life, whereas chickenpox after that time is most likely acquired by postnatal infection. If the mother develops rash between days 4 and 5 antepartum to day 2 postpartum, generalized neonatal varicella leading to death occurs in up to 20% of affected cases. Neonatal chickenpox within the first 4 days after birth has usually been found to be mild. A fatal outcome has been reported in 23% of cases if neonatal chickenpox occurs between 5 and 10 to 12 days of age. Serological methods have been widely used to confirm clinical diagnosis. For rapid virological diagnostics, amplification of viral DNA in skin swabs by polymerase chain reaction is the method of choice. To prevent severe neonatal chickenpox, passive immunization is indicated. If varicella occurs, acyclovir treatment has to be administered promptly.

Simultaneous administration of varicella vaccine and other recommended childhood vaccines--United States, 1995-1999

Live attenuated varicella vaccine (Var) is recommended in the United States for children aged 12-18 months and for susceptible older children, adolescents, and adults. The Advisory Committee on Immunization Practices recommends that Var be administered either simultaneously with measles-mumps-rubella (MMR) vaccine or separately by > or =30 days. This report summarizes an evaluation of these recommendations, which found that a decrease in Var effectiveness occurred when Var was administered <30 days after MMR; therefore, as currently recommended, physicians should administer Var simultaneously with MMR or wait at least 30 days if the vaccines are administered separately.

[Epidemiological analysis of immunity against vaccine-preventable diseases: rubella, measles, mumps and chickenpox]

BACKGROUND AND OBJECTIVE

Measles, mumps, rubella and varicella zoster virus (VZV) infections are regarded as typical diseases of childhood: They are normally clinically mild and result in lifelong immunity. Severe clinical disease is known in immunocompromised patients; rubella virus infections during pregnancy often result in congenital rubella syndrome. All these diseases are preventable by vaccination which is recommended in Germany, recently vaccination against VZV for teenager without immunity since July 2001. In the following study we screened for immunity against the four viruses.

PATIENTS AND METHODS

Serum samples were obtained at the Institute of Medical Virology Frankfurt/Main from January 1999 until December 2000. We tested for specific antibodies against measles (n = 915), against mumps (n = 857), against rubella (n = 1886) and against VZV (n = 2291). Seroprevalences were determined in different age groups.

RESULTS

Altogether the highest rate of seronegatives is detected in younger children. VZV-seronegativity rates decrease from 74 % to 32 % in younger children. Against rubella also in this age group rate of seronegatives is found in 40 % and less than 10 % by teenagers. From this age group also immunity against rubella is found approximately in 80 % of seropositives.

CONCLUSIONS

The following study shows that high seronegative rates are detectable, and here specially against VZV-specific antibodies. For seronegative teenagers, vaccination against VZV is now recommended in Germany. Immunization rates of at least 95 % in childhood would be effective in avoiding severe courses of disease and giving protection in pregnancy.

Epidemiology of primary varicella hospitalizations in Spain

An approach to the burden of varicella can be obtained from information on the hospitalizations. Data were obtained from the national surveillance system for hospital data. All hospital discharges for varicella were analyzed for the 1995-1998 period. A total of 3632 primary varicella-related discharges were identified, representing an annual incidence of 2.8 per 100,000 population. A total of 58% of cases were <10 years of age and 33% were 21-50 years old. Each year primary varicella will be responsible for 6174 days of hospitalization, representing an annual cost of 1.6 million euros. There is substantial severe morbidity each year from varicella that, to reduce, would require vaccination of infants and susceptible adults.

Deaths from chickenpox in England and Wales 1995-7: analysis of routine mortality data

OBJECTIVE

To evaluate the epidemiology and impact of mortality from chickenpox in England and Wales.

DESIGN

Review of death certificates from the Office for National Statistics on which codes for "chickenpox" or "varicella" were mentioned. Further information ascertained from certifying physician.

PARTICIPANTS

Those certified as having died from chickenpox in England and Wales, 1995-7.

MAIN OUTCOME MEASURES

Diagnosis and age and sex distributions of deaths from chickenpox.

RESULTS

On average, 25 people a year die from chickenpox. Overall case fatality was 9.22 per 100 000 consultations for chickenpox. Adults accounted for 81% of deaths and 19% of consultations. Deaths were twice as common in men as in women. More of those who died were born outside United Kingdom than expected (12% v 4%).

CONCLUSIONS

Chickenpox is not a mild disease. Deaths in adults are increasing, both in number and proportion.

Varicella zoster virus. Recent advances in management

OBJECTIVE

To provide an update on strategies for managing varicella zoster virus (VZV) and for preventing and treating established postherpetic neuralgia (PHN).

QUALITY OF EVIDENCE

Treatment guidelines are based on randomized clinical trials. Recommendations concerning other aspects of VZV management (e.g., vaccination) are based mainly on expert opinion.

MAIN MESSAGE

Varicella and herpes zoster caused by VZV can give rise to serious morbidity and mortality and should be treated. For preventing chickenpox, safe and effective immunization is widely recommended. Treating varicella-exposed seronegative pregnant women requires special attention because the virus can harm expectant mothers, fetuses, and newborns. The antiviral drugs, acyclovir, valacyclovir, and famciclovir, have been approved for treating herpes zoster and have a role in reducing the duration of PHN. Established PHN can be managed with analgesics, tricyclic antidepressants, and other agents.

CONCLUSION

Vaccination and antiviral and other systemic agents can substantially reduce the morbidity associated with VZV infection.

Vaccination to prevent varicella and shingles

Vaccination of healthy children against varicella using the live attenuated Oka vaccine has been available in Japan and south Korea for several years. In 1996, a programme of universal vaccination of children to prevent varicella was introduced in the USA and other countries, including Canada, Germany, and Sweden, have licensed the vaccine for use in healthy children. This article reviews the origin of the Oka vaccine and the evidence for vaccine safety and efficacy in children and adults. Universal vaccination of children and targeted vaccination of groups at risk of severe varicella are discussed. The possible use of the Oka vaccine to prevent zoster is reviewed, and initiatives to develop new varicella zoster virus vaccines are outlined.

Epidemiology of varicella zoster virus infection in Canada and the United Kingdom

Many countries are currently studying the possibility of mass vaccination against varicella. The objective of this study was to provide a comprehensive picture of the pre-vaccine epidemiology of the varicella zoster virus (VZV) to aid in the design of immunization programs and to adequately measure the impact of vaccination. Population-based data including physician visit claims, sentinel surveillance and hospitalization data from Canada and the United Kingdom were analysed. The key epidemiological characteristics of varicella and zoster (age specific consultation rates, seasonality, force of infection, hospitalization rates and inpatient days) were compared. Results show that the overall epidemiology of varicella and zoster is remarkably similar between the two countries. The major difference being that, contrary to Canada, the epidemiology of varicella seems to be changing in the United Kingdom with an important decrease in the average age at infection that coincides with a significant increase in children attending preschool. Furthermore, differences exist in the seasonality between the United Kingdom and Canada, which seem to be primarily due to the school calendar. These results illustrate that school and preschool contact patterns play an important role in the dynamics of varicella. Finally, our results provide baseline estimates of varicella and zoster incidence and morbidity for VZV vaccine effectiveness and cost-effectiveness studies.

25 years' experience with the Biken Oka strain varicella vaccine: a clinical overview

Although commonly considered a benign disease in childhood, varicella is a potentially serious infection not only in high risk groups such as children with immune deficiencies, but also in otherwise healthy adults and children. Complications include bacterial superinfections, pneumonia and encephalitis, and the infection can be fatal. In addition to the substantial burden of clinical disease, varicella presents a large economic burden to society. In the absence of a satisfactory treatment for varicella infection, vaccination has an important role in preventing the disease and its sequelae. The original Oka strain live attenuated varicella vaccine was developed in 1974 at the Biken Institute in Japan. Since its development more than 25 years ago, the Biken varicella vaccine has been studied in a large number of clinical trials. The wealth of clinical experience obtained with this vaccine serves to confirm its tolerability, immunogenicity and efficacy in both healthy and high risk individuals. Vaccination has been shown to prevent clinical infection and provide effective protection against the severe complications of varicella. This historical review summarises the long clinical experience with the Biken varicella vaccine and confirms that the vaccine is very well tolerated and provides long term immunity from varicella infection.

[Intravenous immunoglobulins in the prevention of infection in children with hematologic-oncologic diseases]

Treatment with intensive myelosuppressive therapy results in decreased levels of immunoglobulins. Whereas pediatric cancer patients undergoing chemotherapy do not benefit from the routine administration of intravenous immunoglobulins, prophylactic intravenous immunoglobulins given after bone marrow transplantation or after peripheral stem cell transplantation reduce infectious complications. Still, prospective clinical trials are needed to define specific treatment groups who can benefit from immunoglobulin support. In addition, randomized studies are required to evaluate the proper dosage and duration of therapy. Passive immunization of children potentially incubated with varicella or measles is generally recommended.

Parental decision-making for the varicella vaccine

INTRODUCTION

With the advent of new vaccines, improvements in established vaccines, and the availability of new combination vaccines, parents' decisions about vaccinating their children have become more complicated. This study examined parents' decision-making processes pertaining to whether to have their children vaccinated for varicella to gain a better understanding about how parents make vaccination decisions for their children. The "Awareness-to-Action Model" was used to examine parents' decision-making process before the action to vaccinate or refuse vaccination occurs.

METHOD

This study used a cross-sectional design and logistic regression to test the explanatory power of several factors related to the parental decision-making process. A stratified random sample of 262 members of Kaiser Permanente Hawaii participated in the study. Data were collected through telephone interviews.

RESULTS

In the "Awareness-to-Action Model," the decision construct was statistically significant in explaining parents' decisions to have their child vaccinated. The overall model correctly classified 80% of the sample as accepters or nonaccepters of the vaccination for their child. This study provides a model that enables health care providers to understand parental decisions about vaccines. This knowledge can help target interventions to increase vaccine compliance, thus minimizing the risk of diseases preventable by vaccine.

[Antiviral prophylaxis]

Antiviral prophylaxis in pediatric oncology and pediatric bone marrow transplantation (BMT)/stem cell transplantation (SCT) focuses herpes viruses: herpes simplex virus (HSV), varicella zoster virus (VZV) and cytomegalovirus (CMV) since these viruses cause significant morbidity and mortality due to primary infection or to reactivation in long term latency. The majority of studies on antiviral prophylaxis, especially those on CMV-prophylaxis, have been conducted in adult patients. Recommendations for antiviral prophylaxis have been published recently by the German "Deutsche Gesellschaft für pädiatrische Infektiologie" and by the following American institutions and societies "Centers for Disease Control and Prevention", "Infectious Diseases Society of America", "American Society of Blood and Marrow Transplantation" who published the "Guidelines for Preventing Opportunistic Infections Among Hematopoietic Stem Cell Transplant Recipients". Concerning HSV- and VZV-prophylaxis there are almost no differences between recommendations of the german society and the american institutions, however recommendations for preventing CMV-disease and CMV-recurrence do differ considerably. Controversial aspects of antiviral prophylaxis, e.g. VZV vaccination or CMV prevention, should be studied in oncology and infectious diseases working groups to define consensus in the near future.

Impact on immunization of seasonal cycle of chickenpox

The objective of this work was to study the effect of incorporating a seasonal term in a compartmental age-structured theoretical transmission model, on the performance of vaccination strategies for chickenpox. The epidemiologic parameters are taken from data or are based on a review of literature. We used a realistic age-structure model (RAS): It is a model that incorporate both age and seasonal structure. The seasonality was introduced in the model with the addition of sinusoidal forcing term. This seasonal term varies between 0 and 1. From a susceptible/exposed/infectious/removed (SEIR) model with or without age-structure, the pattern of time series is dramatically modified after introducing a seasonal term. This dynamic ends to the transition to chaos. Regarding the evaluation of vaccination strategies, the results of the model without seasonality may be disturbed when the seasonality is introduced, especially during the first 30 years of simulations.

Childhood vaccination against varicella: persistence of antibody, duration of protection, and vaccine efficacy

OBJECTIVE

To document the duration of protection afforded by Oka/Merck varicella vaccine over a 7-year period.

STUDY DESIGN

The subjects were healthy children 1 to 12 years of age originally enrolled in clinical studies to evaluate the primary immune response to varicella vaccine 6 weeks after vaccination. Each was monitored for antibody persistence, breakthrough infection, and household exposure to varicella to produce estimates of vaccine efficacy.

RESULTS

The 6-year cumulative varicella antibody persistence rate was 99.5% (95% CI: 98.9%, 100.0%). The annual breakthrough rate through 7 years ranged from 0.2% to 2.3% per year; the estimated cumulative event rate was 6.5%. Comparison of the observed average annual breakthrough rate with the age-adjusted expected annual incidence rate of varicella in unvaccinated children corresponded to an estimated vaccine efficacy of 93.8% to 94.6%. Eighty vaccinated children were exposed to varicella in the household, resulting in 8 (10%) cases of infection. When compared with the historical attack rate of 86.8% in unvaccinated susceptible persons exposed to varicella in the household, this yields an estimated vaccine efficacy of 88.5% (95% CI: 80.9%, 96.1%). Varicella cases in vaccinated children generally were mild.

CONCLUSION

The live attenuated varicella vaccine is highly effective in inducing persistent immunity and long-term protection against breakthrough varicella infection.

Disseminated vaccine strain varicella as the acquired immunodeficiency syndrome-defining illness in a previously undiagnosed child

The Food and Drug Administration licensed a live-virus varicella vaccine (Varivax; Merck & Co Inc, West Point, PA) in March 1995. Prelicensure adverse events were minimal; however, since licensure and increased vaccine use, rare previously undetected risks have arisen. Presented here is the clinical course of a previously undiagnosed, human immunodeficiency virus-infected boy who developed dissemination of the vaccine strain of varicella zoster after immunization. chickenpox, human immunodeficiency virus, pneumonia, encephalopathy, varicella vaccine, adverse events, dissemination.

Varicella susceptibility among children and healthy adults in the United Arab Emirates

The serological evidence of varicella zoster virus infection was determined among healthy individuals from infancy to 47 years of age living in this region. Of 648 people, 126 (19.4%) had no detectable antibody and were susceptible to infection. The overall adult seroprevalence rate was 81.3%. The rate among Emirati citizens increased with age; < 10 years, 45.8%; 11-20 years, 68.4%; 21-30 years, 89.5%; 31-40 years, 94.7%; and > 41 years, 88.9%. Adults from the Indian subcontinent and Philippines had variable prevalence rates and Sri Lankans living in the region were highly serosusceptible (35%). Because of the clinical impact of varicella in adult populations, vaccine prevention might be beneficial.

Incidence and hospitalization rates of varicella and herpes zoster before varicella vaccine introduction: a baseline assessment of the shifting epidemiology of varicella disease

BACKGROUND

A 15-year postmarketing evaluation of the impact of varicella vaccine on the age distribution of varicella disease is being conducted at Kaiser Permanente Medical Care Program, Northern California (KPMCP). We report on a baseline assessment of the age-specific incidence and hospitalization rates of varicella and herpes zoster that was conducted before vaccine introduction.

METHODS

To assess the annual incidence of varicella, a telephone survey was conducted in a random sample of approximately 8,000 youths 5 to 19 years of age. The annual incidence of hospitalizations for varicella and herpes zoster in 1994 was assessed with the use of the computerized database at KPMCP.

RESULTS

Varicella annual incidence was 10.3% in 5- to 9-year-olds, 1.9% in 10- to 14-year-olds and 1.2% in the 15- to 19-year age groups, respectively. Hospitalization rates among the entire KPMCP membership were 2.6 and 2.1 per 100,000 person years for varicella and zoster, respectively. Varicella incidence in the 15- to 19-year age group was higher among African-Americans than among Caucasians.

CONCLUSIONS

Varicella rates were similar in the 5- to 9- and 10- to 14-year age groups to rates from other published studies conducted in 1972 to 1978, 1980 to 1988 and 1990 to 1992; however, the rate in 15- to 19-year-olds was 2 to 4 times higher than published rates in the same age category.

Prevention and treatment of VZV infections in patients with HIV

Varicella zoster virus (VZV) infections in human immunodeficiency virus (HIV)-infected patients are known to have a different disease spectrum from that seen in other types of patients. Varicella in children with HIV infection is likely to be more serious than in otherwise healthy children and routine antiviral therapy is recommended. There is evidence that the development of varicella in HIV-infected children is not associated with progression to AIDS, suggesting that it may be safe to immunize HIV-infected children with live attenuated varicella vaccine. There are no published data on varicella in HIV-infected adults, however, probably because most adults have already experienced varicella prior to HIV infection. Zoster in HIV-infected children differs somewhat from that in HIV-infected adults. In particular, HIV-infected children who develop varicella in the setting of severe immunodeficiency are at an especially high risk to develop zoster. Given the low rate of toxicity of aciclovir as well as its ease of administration and its efficacy in hastening the healing of VZV infections, prompt treatment with this antiviral agent is recommended for both HIV-infected children and adults. Foscarnet should be used for zoster that is strongly suspected or proven to be caused by aciclovir-resistant VZV. Patients with HIV for whom there is no evidence of significant immunosuppression and who have not had varicella should be immunized with live attenuated varicella vaccine as a preventative measure for both varicella and zoster. It is hoped that immunization of VZV seropositive HIV-infected patients will decrease the incidence of zoster. Studies to determine this are under way.

IL-12, IFN-gamma, and TNF-alpha released from mononuclear cells inhibit the spread of varicella-zoster virus at an early stage of varicella

The activity of mononuclear cells to inhibit plaque formation of varicella-zoster virus (VZV) was investigated by an in vitro infectious center assay. Peripheral blood mononuclear cells (PBMC) inhibited VZV plaque formation by co-cultivation with VZV-infected fibroblasts. As compared to mononuclear cells from normal individuals, mononuclear cells from umbilical cord blood and from patients receiving corticosteroids showed a significant decrease in the ability to inhibit viral replication. This ability was significantly increased for mononuclear cells collected during the acute phase of varicella. PBMC obtained from patients in the acute phase of varicella produced significantly higher amounts of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-12 in the supernatant compared with those of healthy individuals. These data suggest that the cytokines have an important role in the inhibition of the spread of VZV at an early stage of varicella. Th1 type adaptive immunity might play a major role in VZV infection.