Varicella among adults: data from an active surveillance project, 1995-2005

The impact of the implementation of the two-dose varicella vaccine immunization strategy in Quzhou: A retrospective birth cohort study

Varicella is a vaccine-preventable disease caused by the varicella zoster virus (VZV), but the varicella incidence among children has increased in recent years. This was a retrospective birth cohort study based on the Zhejiang Provincial Immune Information System (ZJIIS) and the China Information System for Disease Control and Prevention (CISDCP) in Quzhou. A total of 1,291 clinically diagnosed varicella cases born from 2009 to 2014 were collected during 2009-2023, which were analyzed the impact of changes in vaccination strategy on the incidence of varicella based on the Cox-proportional hazards model. It was observed that the onset age of varicella shifted to the older age group and later to 9-11 years. After the change to the two-dose varicella vaccination strategy, the population affected by varicella was concentrated among students and received more than one dose of live attenuated varicella vaccine (VarV). Based on the Coxproportional hazards model and adjusting for all covariates, the risk of varicella infection in children decreased after the introduction of the two-dose varicella vaccination strategy (HR = 0.04, 95% CI: 0.03-0.05). Meanwhile, the Kaplan-Meier curves also showed that the hazards were lower after the change in vaccination strategy. It is recommended that two doses of VarV should be included in the national immunization schedule and that full vaccination should be completed approximately four years after the first dose.

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.

A Rare Case of Chickenpox Infection Complicated by Hip Septic Arthritis

Chickenpox represents a viral malady characterized by the emergence of vesicular skin eruptions. This ailment is frequently encountered during childhood and typically manifests a benign course devoid of complications. Among the prevalent complications, secondary bacterial skin infections ranging from superficial impetigo to subcutaneous abscesses are most frequently observed. Instances of musculoskeletal complications, such as septic arthritis and osteomyelitis, are rarely observed. In any patient presenting complaints of bone pain or arthralgia, either during varicella eruptions or during the healing process, it is imperative to maintain a vigilant consideration for the potential manifestation of septic arthritis and osteomyelitis. Timely diagnosis holds paramount importance, as the administration of appropriate antibiotics can effectively forestall the necessity for surgical interventions and mitigate the risk of sequela. In this context, we present a case wherein chickenpox resulted in the complication of right hip septic arthritis.

Identification of novel potential inhibitors of varicella-zoster virus thymidine kinase from ethnopharmacologic relevant plants through an in-silico approach

Although Varicella or chickenpox infection which is caused by the varicella-zoster virus (VZV) has significantly been managed through vaccination, it remains an infection that poses threats to the nearest future due to therapeutic drawbacks. The focus of this research was geared towards in silico screening for the identification of novel compounds in plants of ethnopharmacological relevance in the treatment of chicken pox in West Africa. The work evaluated 65 compounds reported to be present in Achillea millefolium, Psidium guajava and Vitex doniana sweet to identify potential inhibitors of thymidine kinase, the primary drug target of varicella zoster virus. Out of the 65 compounds docked, 42 of these compounds were observed to possess binding energies lower than -7.0 kcal/mol, however only 20 were observed to form hydrogen bond interactions with the protein. These interactions were elucidated using LigPlot⁺ and MM-PBSA analysis with residue Ala134 predicted as critical for binding. Pharmacological profiling predicted three potential lead compounds comprising myricetin, apigenin- 4' -glucoside and Abyssinone V to possess good pharmacodynamics properties and negligibly toxic. The molecules were predicted as antivirals including anti-herpes and involved in mechanisms comprising inhibition of polymerase, ATPase and membrane integrity, which were corroborated previously in other viruses. These drug-like compounds are plausible biotherapeutic moieties for further biochemical and cell-based assaying to discover their potential for use against chickenpox. Communicated by Ramaswamy H. Sarma.

Cost effectiveness and budget impact of universal varicella vaccination in Russia

This economic evaluation assesses the cost-effectiveness and budget impact of introducing a two-dose varicella vaccine in the Russian national immunization program. A static Markov model followed a simulated 2019 Russian cohort over its lifetime and compared outcomes and costs of three varicella vaccination strategies: strategy I (doses given at 12 and 15 months of age), strategy II (doses given at 1 year and 6 years of age), and a no vaccination scenario. Inputs on age-dependent clinical pathways, associated costs, and related health outcomes were collected from national sources and published literature. Results are presented as incremental cost-effectiveness ratio (ICER) from the healthcare payer and societal perspective over the lifetime of the birth cohort and the budget impact over a 10 years' time horizon. Vaccination strategies I and II resulted in an ICER of approximately 1.7 million rubles per quality-adjusted life years gained from the healthcare payer perspective and were cost-saving from the societal perspective. From the healthcare payer perspective, the costs per varicella case averted were 5,989 and 7,140 rubles per case for strategies I and II, respectively. However, from the societal perspective, vaccination is a dominant strategy and the budget impact analysis shows significant healthcare savings over 10 years, with strategy I realizing savings of ~2 billion rubles more than strategy II. From a public health impact perspective, varicella vaccination of children at 12 and 15 months of age through the Russian NIP is expected to be cost-effective with an affordable budget impact compared to no vaccination.

Long-term vaccine efficacy of a 2-dose varicella vaccine in China from 2011 to 2021: A retrospective observational study

Objective

A 2-dose varicella vaccine immunization strategy has been implemented in many cities in China, but there is few evidence on a long-term evaluation of the efficacy of the 2-dose varicella vaccine from China. This study aims to assess the long-term vaccine efficacy of the two doses varicella vaccine and analysis of its influencing factors.

Methods

A retrospective study was carried out in 837,144 children born between 2011 and 2017 in Ningbo, Easten China. The logistic regression was performed to estimate varicella vaccine effectiveness (VE).

Results

The overall VE of 2 doses of varicella vaccine compared without the vaccine was 90.31% (89.24-91.26%), and the overall incremental VE of 2 doses of varicella vaccine compared to the 1-dose was 64.71% (59.92-68.93%). Moreover, the varicella vaccination age of the second dose and the interval between 2 doses were both associated with VE. The VE compared to that without the vaccine in children vaccinated at <4 years old was 91.22% (95%CI: 90.16-92.17%) which was higher than in children vaccinated at ≥4 years old (VE: 86.79%; 95%CI: 84.52-88.73). And the effectiveness of the vaccine was 93.60% (95%CI: 92.19-94.75%) in children with the interval of the 2 doses ≤ 24 months significantly higher than in children with the interval of ≥36 months (VE: 85.62%, 95%CI: 82.89-87.91%).

Conclusions

This study provides evidence for long-term VE of the 2-dose varicella vaccine and the better age for 2-dose vaccination and the interval between 2 doses of the vaccine in China.

Pneumonia and Meningoencephalitis Due to Varicella-zoster Virus Reinfection and Epstein-Barr Virus Reactivation in a Patient with Rheumatoid Arthritis

A 72-year-old woman with rheumatoid arthritis was treated with methotrexate (MTX) and iguratimod. Upon examination of a liver tumor, blisters due to varicella-zoster virus (VZV) infection were observed. Despite oral administration of valacyclovir, she developed varicella pneumonia and meningoencephalitis. A VZV antibody test revealed reinfection. The liver tumor shrank after discontinuance of MTX, and polymerase chain reaction revealed the reactivation of the Epstein-Barr virus (EBV). Therefore, we were unable to deny MTX-associated lymphoproliferative disorder (MTX-LPD). This is the first case of a complication of pneumonia and meningoencephalitis due to VZV reinfection and EBV reactivation.

Containment of varicella outbreak in intensive care unit of a tertiary level hospital

BACKGROUND

Varicella-Zoster virus (VZV) infection in healthcare organizations, especially in intensive care units (ICU), having admitted immunocompromised patients, is of serious concern as well as poses threat to healthcare workers working in such critical areas. The present report defines the transmission and infection control measures initiated to curtail VZV infection spread in the trauma ICU of a tertiary care hospital of North India.

OUTBREAK REPORT

At the infection outset, there were 12 patients admitted in ICU and 54 healthcare workers were posted to manage these critical patients. After confirmation of VZV infection, all susceptible patients as well as healthcare workers were quarantined and fresh intake of patients was restricted. Out of the total healthcare workers, 14 (25.92%) were found susceptible (as per protective VZV IgG titers) and were vaccinated. Of the 12 patients admitted in the ICU, six patients were discharged and sent home directly, four patients expired due to their critical disease state, one patient left against medical advice, and one patient remained admitted in ICU till the incubation period was over. Epidemiologically, line listing for index case reporting was done. The efficacy of control measures was re-evaluated to strengthen existing infection control practices and general measures viz. strict hand washing, adherence to aseptic protocols and intensification of environmental cleaning.

CONCLUSIONS

Established varicella surveillance measures ensure VZV outbreaks are identified in a timely manner and control measures implemented to prevent further transmission. Also, vaccination policy among HCWs is the utmost requirement despite having huge financial implications.

A co-infection of varicella-zoster virus and Pneumocystis jirovecii in a non-HIV immunocompromised patient: a case report

Background

Varicella-zoster virus (VZV) causes herpes zoster. Pneumocystis jirovecii (PJ) also causes pneumonia in immunocompromised hosts. Although both cause opportunistic infections, it is rare to have a co-infection in a non-human immunodeficiency virus carrier.

Case presentation

An 84-year-old woman with hemolytic anemia referred because of acute respiratory failure. She had received prednisolone without PJ pneumonia prevention. She developed dyspnea and desaturation while eating, and thus was treated based on a presumptive diagnosis of aspiration pneumonia. Physical examination revealed a vesicular rash on the left side of her neck suggesting herpes zoster infection. Polymerase chain reaction of her sputum for PJ and VZV was positive, which confirmed a diagnosis of pneumonia due to PJ and VZV co-infection. Despite acyclovir and sulfamethoxazole and trimethoprim administration, she died on hospital day 19.

Conclusions

Clinicians should suspect PJP when patients on systemic corticosteroids develop pneumonia and they have not received prophylactic treatment for PJP in non-HIV carriers. When such patients have a VZV rash, clinicians should aggressively seek signs of opportunistic infections. Our case hereby highlights the importance of recognizing the possibility of a VZV and PJ co-infection.

Implementation of Hospital Policy for Healthcare Workers and Patients Exposed to Varicella-Zoster Virus

Varicella-zoster virus (VZV) causes a highly contagious and generally benign, self-limited disease. However, in high-risk populations including immunocompromised patients, pregnant women, and neonates, VZV infection can be associated with significant morbidity and mortality. Healthcare-associated transmission of VZV occurs among healthcare workers (HCWs) and patients by airborne transmission or by direct contact with the index case. To minimize the risk of transmission in healthcare settings, all VZV-susceptible HCWs should be encouraged strongly to be immunized with the varicella vaccine. For post-exposure management, active immunization (varicella vaccine), passive immunization (varicella-zoster immune globulin) and/or antiviral agents, and isolation could be used in specific situations. To prevent the transmission of VZV infection in the hospital settings, the development and implementation of hospital policies for appropriate infection control is also warranted. This article reviews the general information and healthcare-associated transmission of VZV and summarizes the recommendations for the pre- and post-exposure management of HCWs and patients, in hospital settings.

Maritime varicella illness and death reporting, U.S., 2010-2015

BACKGROUND

Ships destined for, or departing from, U.S. ports of entry must report certain signs and symptoms of potentially communicable diseases of public health interest among travelers to the Division of Global Migration and Quarantine (DGMQ) at the Centers for Disease Control and Prevention.

METHODS

We reviewed ships' varicella case and outbreak reports from January 2010 through December 2015.

RESULTS

DGMQ received 967 reports of varicella and 13 reports of herpes zoster. Most varicella case-patients were 20-49 years of age (84.7%, 472/557) and were cruise ship crew members (78.4%, 758/967). Most often, cruise ship crew member case-patients were born in or held passports from Indonesia (21.7%, 80/369), Philippines (17.6%, 65/369), or India (17.3%, 64/369). Ninety-nine varicella outbreaks were reported, including 439 varicella cases and one herpes zoster case; 97 (98.0%) outbreaks occurred on cruise ships, and 90.2% of associated cases were among crew members (397/440). Most varicella cases were in crew members, who are adults often from tropical regions where varicella immunity is acquired later in childhood or young adulthood or without varicella vaccination programs.

CONCLUSION

Varicella vaccination as appropriate for susceptible travelers, particularly crew members, before maritime travel may decrease risk of varicella infection and prevent outbreaks on ships.

Acute Kidney Failure as a Single Complication of Varicella Virus Infection in an Adult Patient

BACKGROUND

Varicella zoster virus (VZV) is distributed worldwide and is highly contagious. In adults and immunosuppressed patients of any age, the clinical course is much more severe. The most severe complications are pneumonia (the main cause of lethal outcomes in this infection), encephalitis, and very rarely Reye syndrome and hepatitis.

CASE PRESENTATION

We present a 59-year-old man who came to the emergency department due to varicella and diarrhea. During initial evaluation acute kidney failure (AKF) was diagnosed, and the patient was admitted to the intensive care unit. Continuous renal replacement therapy was applied, and the patient was treated with acyclovir in adjusted doses; renal biopsy revealed acute tubular necrosis. Complete renal function recovery was established after 12 days.

CONCLUSION

VZV infection occurs in a range of clinical scenarios, sometimes presenting only with mild symptoms, but in some other setting it can result in severe AKF even in healthy kidneys. Acute VZV infection can lead to isolated, clinically significant kidney failure. The administration of continuous renal replacement therapy and adjusted doses of acyclovir has a favorable effect on the course of the infection, with complete recovery of kidney function.

Serological Susceptibility to Varicella Among U.S. Immigration and Customs Enforcement Detainees

U.S. Immigration and Customs Enforcement (ICE) is responsible for detaining unauthorized aliens during immigration proceedings. During 2014 to 2015, adult ICE detainees at a California facility were invited to complete a survey concerning self-reported varicella history and risk factors. Participants underwent serological testing for varicella-zoster virus (VZV) IgG; susceptible individuals were offered varicella vaccination. Among 400 detainees with available serology results, 48 (12%) were susceptible to varicella. Self-reported varicella history was negatively associated with susceptibility (adjusted odds ratio = 0.16; 95% confidence interval [0.07, 0.35]). Among 196 detainees reporting a positive history, 95% had VZV IgG levels suggestive of varicella immunity. Among 44 susceptible detainees offered vaccination, 86% accepted. Given relatively high varicella susceptibility, targeted screening and vaccination among ICE detainees lacking a positive history might reduce varicella transmission risks.

Safety and immunogenicity of Bio Pox™, a live varicella vaccine (Oka strain) in Indian children: A comparative multicentric, randomized phase II/III clinical trial

Varicella or chickenpox is a highly contagious disease with a high secondary attack rate. Almost 30% of Indian adolescents lack protective antibodies against varicella, emphasizing the need of routine varicella immunization. The Oka VZV is a well-established, safe and efficacious vaccine strain that is highly immunogenic and produces lifelong protective immunity. The present multicentric, open label, randomized, controlled Phase II/III study, compared the Bio Pox™ (indigenous investigational vaccine) with a licensed vaccine, Varivax™ ^[a][a] Please note that this article refers to the product named VARIVAX as manufactured by Changchun Keygen Biological Products Ltd., China and marketed in India by VHB Life Sciences Limited, Mumbai, and not the product VARIVAX® owned by Merck Sharp & Dohme Corp., Rahway, New Jersey, USA. Merck Sharp & Dohme Corp. have asked us to make clear that the product manufactured by Changchun Keygen Biological Products Ltd. is unrelated to and is not sponsored, endorsed or otherwise authorised by Merck Sharp & Dohme Corp. , for its safety and immunogenicity profile in 252 healthy subjects in the age group of 1-12 y (cohort I: 6-12 years, II:1-6 years) in 3 tertiary medical institutions. Antibodies were measured by VZV Glycoprotein Enzyme Linked Immunoassay (IgG ELISA) kit. Seroconversion percentage in children having pre-vaccination anti VZV IgG titer <10 mIU/mL (< 5 gp ELISA units/mL) were 80% for Bio Pox™ and 77% for Varivax™ (p = 0.692). The seroconversion rate in the group receiving Bio Pox™ was non-inferior to the group that received Varivax™. There were mild local reactions for both the vaccines; none of the patient had fever or required hospitalization or medication. The Bio Pox™ was found to be safe and immunogenic in children against VZV infection.

Varicella Coinfection in Patients with Active Monkeypox in the Democratic Republic of the Congo

From 2006 to 2007, an active surveillance program for human monkeypox (MPX) in the Democratic Republic of the Congo identified 151 cases of coinfection with monkeypox virus and varicella zoster virus from 1158 suspected cases of human MPX (13%). Using clinical and socio-demographic data collected with standardized instruments by trained, local nurse supervisors, we examined a variety of hypotheses to explain the unexpectedly high proportion of coinfections among the sample, including the hypothesis that the two viruses occur independently. The probabilities of disease incidence and selection necessary to yield the observed sample proportion of coinfections under an assumption of independence are plausible given what is known and assumed about human MPX incidence. Cases of human MPX are expected to be underreported, and more coinfections are expected with improved surveillance.

Rash Decisions: An Approach to Dangerous Rashes Based on Morphology

BACKGROUND

Rash is a common complaint in the emergency department. Many causes of rash are benign; however, some patients may have a life-threatening diagnosis.

OBJECTIVE

This review will present an algorithmic approach to rashes, focusing on life-threatening causes of rash in each category.

DISCUSSION

Rash is common, with a wide range of etiologies. The differential is broad, consisting of many conditions that are self-resolving. However, several conditions associated with rash are life threatening. Several keys can be utilized to rapidly diagnose and manage these deadly rashes. Thorough history and physical examination, followed by consideration of red flags, are essential. This review focuses on four broad categories based on visual and tactile characteristic patterns of rashes: petechial/purpuric, erythematous, maculopapular, and vesiculobullous. Rashes in each morphologic group will be further categorized based on clinical features such as the presence or absence of fever and distribution of skin lesions.

CONCLUSIONS

Rashes can be divided into petechial/purpuric, erythematous, maculopapular, and vesiculobullous. After this differentiation, the presence of fever and systemic signs of illness should be assessed. Through the breakdown of rashes into these classes, emergency providers can ensure deadly conditions are considered.

Resurgence of Vaccine-Preventable Diseases in the United States: Anesthetic and Critical Care Implications

Vaccine-preventable diseases (VPDs) such as measles and pertussis are becoming more common in the United States. This disturbing trend is driven by several factors, including the antivaccination movement, waning efficacy of certain vaccines, pathogen adaptation, and travel of individuals to and from areas where disease is endemic. The anesthesia-related manifestations of many VPDs involve airway complications, cardiovascular and respiratory compromise, and unusual neurologic and neuromuscular symptoms. In this article, we will review the presentation and management of 9 VPDs most relevant to anesthesiologists, intensivists, and other hospital-based clinicians: measles, mumps, rubella, pertussis, diphtheria, influenza, meningococcal disease, varicella, and poliomyelitis. Because many of the pathogens causing these diseases are spread by respiratory droplets and aerosols, appropriate transmission precautions, personal protective equipment, and immunizations necessary to protect clinicians and prevent nosocomial outbreaks are described.

Potential impact of dengue vaccination: Insights from two large-scale phase III trials with a tetravalent dengue vaccine

BACKGROUND

A tetravalent dengue vaccine demonstrated its protective efficacy in two phase III efficacy studies. Results from these studies were used to derive vaccination impact in the five Asian (Indonesia, Malaysia, Philippines, Thailand, Vietnam) and the five Latin American countries (Brazil, Colombia, Honduras, Mexico and Puerto Rico) participating in these trials.

METHODS

Vaccination impact was investigated with an age-structured, host-vector, serotype-specific compartmental model. Parameters related to vaccine efficacy and levels of dengue transmission were estimated using data collected during the phase III efficacy studies. Several vaccination programs, including routine vaccination at different ages with and without large catch-up campaigns, were investigated.

RESULTS

All vaccination programs explored translated into significant reductions in dengue cases at the population level over the first 10years following vaccine introduction and beyond. The most efficient age for vaccination varied according to transmission intensity and 9years was close to the most efficient age across all settings. The combination of routine vaccination and large catch-up campaigns was found to enable a rapid reduction of dengue burden after vaccine introduction.

CONCLUSION

Our analysis suggests that dengue vaccination can significantly reduce the public health impact of dengue in countries where the disease is endemic.

Immunogenicity and safety of different schedules of 2-dose varicella vaccination in China

We evaluated the safety and immunogenicity of different time intervals for a second dose of varicella vaccine in children in Zhejiang Province, China. Participants had all received a first dose of varicella vaccine and were assigned to 4 groups according to age (2-7 years). A second dose of live attenuated varicella vaccine was administered 1 month, 1 year, 3 years, or 5 years after the first. A serology assay was conducted and fluorescent-antibody-to-membrane-antigen test performed to measure the antibody titers against varicella before and approximately 30 days after the second dose. Of 1,078 participants, most tolerated the second dose well. Age at first dose did not affect the response to vaccination. Geometric mean titers (GMTs) significantly differed between group 1 and all other groups, both before and after the second vaccination. The GMT for group 1 was higher than those for the other 3 groups prior to the second vaccination (GMT = 20.52, 14.68, 12.49, 12.29, respectively, p < 0.001 for all), while the opposite was true after the second vaccination (GMT = 51.14, 83.37, 85.01, 81.83, respectively, p < 0.001 for all). There was no significant difference in seropositive rate among the 4 groups prior to the second vaccination (p = 0.093), and these rates were all 100% after the second vaccination. The vaccine was well tolerated in healthy children, regardless of the timing of the second dose. GMTs showed a particularly high boost after the second dose when the interval between doses was more than 1 year.

Varicella outbreak in Sudanese refugees from Calais

We describe an outbreak of varicella in 31 Sudanese refugees (all except one were male, mean age: 26 ± 1), from the Calais migrant camp and sheltered in a French transit area. The attack rate was 39%. Adults are scantly immunized against varicella zoster virus in East Africa and may be exposed to epidemics once in France.

Epidemic cycling in a multi-strain SIRS epidemic network model

Background

One common observation in infectious diseases caused by multi-strain pathogens is that both the incidence of all infections and the relative fraction of infection with each strain oscillate with time (i.e., so-called Epidemic cycling). Many different mechanisms have been proposed for the pervasive nature of epidemic cycling. Nevertheless, the two facts that people contact each other through a network rather than following a simple mass-action law and most infectious diseases involve multiple strains have not been considered together for their influence on the epidemic cycling.

Methods

To demonstrate how the structural contacts among people influences the dynamical patterns of multi-strain pathogens, we investigate a two strain epidemic model in a network where every individual randomly contacts with a fixed number of other individuals. The standard pair approximation is applied to describe the changing numbers of individuals in different infection states and contact pairs.

Results

We show that spatial correlation due to contact network and interactions between strains through both ecological interference and immune response interact to generate epidemic cycling. Compared to one strain epidemic model, the two strain model presented here can generate epidemic cycling within a much wider parameter range that covers many infectious diseases.

Conclusion

Our results suggest that co-circulation of multiple strains within a contact network provides an explanation for epidemic cycling.

Dissecting the indirect effects caused by vaccines into the basic elements

Vaccination directly protects vaccinated individuals, but it also has the potential for indirectly protecting the unvaccinated in a population (herd protection). Unintended negative consequences such as the re-manifestation of infection, mainly expressed as age shifts, result from vaccination programs as well. We discuss the necessary conditions for achieving optimal herd protection (i.e., high quality vaccine-induced immunity, substantial effect on the force of infection, and appropriate vaccine coverage and distribution), as well as the conditions under which age shifts are likely to occur. We show examples to illustrate these effects. Substantial ambiguity in observing and quantifying these indirect vaccine effects makes accurate evaluation troublesome even though the nature of these outcomes may be critical for accurate assessment of the economic value when decision makers are evaluating a novel vaccine for introduction into a particular region or population group. More investigation is needed to identify and develop successful assessment methodologies for precisely analyzing these outcomes.

One-dose vaccination associated with attenuated disease severity of adolescent and adult varicella cases in Beijing's Fengtai District

BACKGROUND

In recent years, the number of varicella cases in adults has significantly increased in Beijing. However, the effect of the vaccination on varicella-related characteristics among adults has not been studied.

METHODS AND RESULTS

Using data from the Infectious Disease Reporting System and the Immunization Information System, we compared the epidemiology and disease severity in breakthrough and unvaccinated varicella cases in adolescents and adults (≥ 15 year-old) from 2008 to 2011 in Beijing's Fengtai district, China. The results showed that the age (P = 0.003),contact history (90% vs. 73%, P = 0.019) and outbreak cases (10% vs. 1%, P < 0.0001) were significantly differently distributed between the two groups and that both the incidence of moderate-to-severe cases (26% vs. 45%, P = 0.035, OR = 0.446) and varicella-associated fever (49% vs. 66%, P = 0.068, OR = 0.534) were either significantly lower or trended to be lower in the breakthrough group than in the unvaccinated group. Additionally,vaccine effectiveness against moderate-to-severe cases of varicella was 55.4%.

CONCLUSION

Altogether, these results indicate that vaccination against varicella among adolescents and adults affected the epidemiology and attenuated the disease severity of the cases. The Results from this study will provide useful information for the prevention of varicella in adolescents and adults.

Determining the persistence of maternally acquired antibodies to hepatitis A and varicella zoster during the first 2 years of life in Turkey

Vaccination should be timed to take into account the potential interference of maternal antibodies. The purpose of this study was to determine the persistence of maternally acquired antibodies to hepatitis A and varicella zoster in a group of healthy infants between 6 and 24 months of age. These infants were divided into four groups according to the age at the time of follow-up visits. The study group consisted of infants who were brought to the 6-month follow-up visit (group 1, n=100), 12-month follow-up visit (group 2, n=99), 18-month follow-up visit (group 3, n=59), and 24-month follow-up visit (group 4, n=59). Hepatitis A, varicella IgG, and IgM antibodies were analyzed qualitatively. Hepatitis A IgG seropositivity was determined as 71 % in group 1, 41.4 % in group 2, 0 % in group 3, and 8.5 % in group 4 (p<0.001). Varicella IgG seropositivity was found to be 5 % in group 1, 4 % in group 2, 4 % in group 3, and 1 % in group 4 (p>0.05).

CONCLUSION

We found that maternal hepatitis A antibodies in children disappear between 12 and 18 months, whereas maternal varicella antibodies substantially diminish following the sixth month. Therefore, the vaccination timing should be based on factors such as the interference of maternal antibodies, disease susceptibility period, and immune maturation.

Periodicity of varicella-zoster virus in the presence of immune boosting and clinical reinfection with varicella

BACKGROUND

Clinical reinfection with varicella is normally ignored in mathematical transmission models as it is considered too rare to be important.

METHODS

We apply basic bifurcation analysis to a simple mathematical model of varicella-zoster virus (VZV) transmission incorporating reinfection.

RESULTS

We demonstrate that under certain conditions this model can exhibit periodic behaviour as opposed to what is observed in VZV models that ignore the possibility of repeat varicella attacks. Periodicity can be induced by a combination of immune boosting and reinfection while the impact of zoster (shingles) recurrence on the onset of periodicity is negligible.

CONCLUSIONS

Our results suggest that mathematical models of VZV may benefit from inclusion of repeat varicella.

Varicella-zoster virus immunity among health care workers in Catalonia

OBJECTIVE

To determine varicella-zoster virus (VZV) immunity among healthcare workers (HCWs). Cross-sectional study.

PARTICIPANTS

HCWs attending voluntary periodic health examinations between June 2008 and December 2010.

SETTING

Six public hospitals and five primary care areas in Catalonia, Spain.

METHODS

A self-administered questionnaire was given to eligible HCWs. Variables including age, sex, professional category, type of centre, history of varicella infection, and VZV vaccination were collected. The study was carried out using a convenience sample. The prevalence of antibodies and positive and negative predictive values (PPV and NPV) of the history of clinical VZV infection or vaccination were calculated. Crude and adjusted odds ratios (OR and ORa) and their 95% confidence intervals (CI) were calculated to determine the variables associated with antibody prevalence.

RESULTS

Of 705 HCWs who agreed to participate, 644 were finally included. The overall prevalence of antibodies to varicella was 94.9% (95% CI: 92.9-96.4). Of the variables studied, only age was associated with serological susceptibility to VZV. HCWs aged 25-35 years had the highest serological susceptibility (8.1%, 95% CI: 4.6-13.0). The prevalence of antibodies was 96% in subjects reporting previous VZV infection or vaccination, compared with 93% in subjects who did not report these states or did not know.

CONCLUSIONS

The high proportion of serologically-susceptible HCWs found in this study indicates the need to develop for screening and vaccination strategies in Catalonia. Due to the high capacity of propagation of the VZV in health settings and its consequences, VZV vaccination programmes in HCWs should be reinforced.

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.

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.

Delayed primary HHV-7 infection and neurologic disease

BACKGROUND

Primary human herpesvirus 7 (HHV-7) infection occurs almost universally during the first 5 years of life and is rarely accompanied by central nervous system (CNS) symptoms such as febrile seizures. The present retrospective study investigated the role of primary HHV-7 infection in CNS disease in children, including adolescents.

METHODS

The study included all children who had neurologic disease aged younger than 18 years seen at the Hospital for Sick Children, Toronto, Canada, between April 1, 1998 and December 31, 2011, whose cerebrospinal fluid (CSF) was found by polymerase chain reaction to contain HHV-7 DNA. Where sera were available, HHV-7 IgG antibody titers and avidity were measured to differentiate primary from past infection.

RESULTS

HHV-7 DNA was detected in the CSF of 57 (1.9%) of the 2972 children tested. In 3 adolescents primary HHV-7 infection (low avidity IgG) was confirmed as the cause of neurologic disease, 2 who had encephalitis and 1 who had Guillain-Barré syndrome. Eighteen children had possible HHV-7 disease (no alternative cause identified and indeterminate antibody result or serum not available), 7 encephalitis, 8 meningitis, and 3 demyelinating disorders. HHV-7 disease was excluded in 36 children on the basis of past infection (high IgG avidity) and/or an alternative cause.

CONCLUSIONS

Primary HHV-7 infection delayed into adolescence can cause serious neurologic disease. HHV-7 DNA in CSF alone is insufficient to prove an etiologic association. Combining CSF polymerase chain reaction with serology is essential to prove primary infection when investigating HHV-7 CNS disease.

[Varicella vaccination in Germany. A provisional appraisal in the context of MMR vaccination]

In 2004, a general varicella immunization was introduced in Germany for infants from the age of 11 months, followed by the subsequent recommendation in 2009 of a second vaccine dose. The vaccination is carried out at the same time as the immunization against measles, mumps, and rubella (MMR). Results of the nationwide sentinel surveillance of varicella and herpes zoster implemented by the Varicella Working Group (Arbeitsgemeinschaft Varizellen, AGV) show that the defined goals for varicella immunization (reduction of varicella-related morbidity, complications and hospitalizations) have been reached within a few years owing to the advances in vaccine coverage. Although coverage rates for varicella have not yet reached the same levels as for MMR, varicella immunization seems to have benefited from the established MMR immunization schedule. Moreover, there is no evidence for an adverse effect on the use and acceptance of the MMR vaccine. Lessons learnt in measles epidemiology (such as trends in the incidence of the disease in adolescents and infants), as well as in the history of MMR recommendations, may be useful for the evaluation of future epidemiological changes with respect to varicella and herpes zoster. In view of a rapidly waning immunity against the varicella zoster virus after vaccination with one dose and the lifelong persistence of the virus, achieving a robust and sustainable immunity in the general population seems to be an ambitious goal. However, this accomplishment will be indispensable in preventing breakthrough infections and a shift of varicella to older ages and in avoiding an increase in herpes zoster incidence.

Vaccination to prevent varicella: Goldman and King's response to Myers' interpretation of Varicella Active Surveillance Project data

BACKGROUND

There is increasing evidence that herpes zoster (HZ) incidence rates among children and adults (aged <60 years) with a history of natural varicella are influenced primarily by the frequency of exogenous exposures, while asymptomatic endogenous reactivations help to cap the rate at approximately 550 cases/100,000 person-years when exogenous boosting becomes rare. The Antelope Valley Varicella Active Surveillance Project was funded by the Centers for Disease Control and Prevention in 1995 to monitor the effects of varicella vaccination in one of the three representative regions of the United States. The stability in the data collection and number of reporting sites under varicella surveillance from 1995-2002 and HZ surveillance during 2000-2001 and 2006-2007 contributed to the robustness of the discerned trends.

DISCUSSION

Varicella vaccination may be useful for leukemic children; however, the target population in the United States is all children. Since the varicella vaccine inoculates its recipients with live, attenuated varicella-zoster virus (VZV), clinical varicella cases have dramatically declined. Declining exogenous exposures (boosts) from children shedding natural VZV have caused waning cell-mediated immunity. Thus, the protection provided by varicella vaccination is neither lifelong nor complete. Moreover, dramatic increases in the incidence of adult shingles cases have been observed since HZ was added to the surveillance in 2000. In 2013, this topic is still debated and remains controversial in the United States.

SUMMARY

When the costs of the booster dose for varicella and the increased shingles recurrences are included, the universal varicella vaccination program is neither effective nor cost-effective.

Risk factors for susceptibility to varicella in newly arrived adult migrants in Canada

Varicella occurs at an older age in tropical compared to cold climates. Migrants from tropical countries provide the opportunity to gain insights into observed global differences in varicella epidemiology. Severity of varicella increases with age thus, description of risk factors for varicella susceptibility will identify those who would benefit most from vaccination. A total of 1480 migrants, with a mean age of 32 years, were recruited in the pre-vaccination period (2002-2004) in Montreal, Canada. A questionnaire was administered and serum varicella antibodies were measured. Overall 6% were susceptible and ranged from 0·8% to 14·1% in subgroups. Risk factors for susceptibility were younger age, recent arrival, and originating from a tropical country. This could be modified by conditions that increased the probability of person-to-person spread of varicella through direct contact in source countries such as larger community size or household crowding. Many new young adult migrants would benefit from targeted varicella vaccination programmes.

Impact of a routine two-dose varicella vaccination program on varicella epidemiology

OBJECTIVE

One-dose varicella vaccination for children was introduced in the United States in 1995. In 2006, a second dose was recommended to further decrease varicella disease and outbreaks. We describe the impact of the 2-dose vaccination program on varicella incidence, severity, and outbreaks in 2 varicella active surveillance areas.

METHODS

We examined varicella incidence rates and disease characteristics in Antelope Valley (AV), CA, and West Philadelphia, PA, and varicella outbreak characteristics in AV during 1995-2010.

RESULTS

In 2010, varicella incidence was 0.3 cases per 1000 population in AV and 0.1 cases per 1000 population in West Philadelphia: 76% and 67% declines, respectively, since 2006 and 98% declines in both sites since 1995; incidence declined in all age groups during 2006-2010. From 2006-2010, 61.7% of case patients in both surveillance areas had been vaccinated with 1 dose of varicella vaccine and 7.5% with 2 doses. Most vaccinated case patients had <50 lesions with no statistically significant differences among 1- and 2-dose cases (62.8% and 70.3%, respectively). Varicella-related hospitalizations during 2006-2010 declined >40% compared with 2002-2005 and >85% compared with 1995-1998. Twelve varicella outbreaks occurred in AV during 2007-2010, compared with 47 during 2003-2006 and 236 during 1995-1998 (P < .01).

CONCLUSIONS

Varicella incidence, hospitalizations, and outbreaks in 2 active surveillance areas declined substantially during the first 5 years of the 2-dose varicella vaccination program. Declines in incidence across all ages, including infants who are not eligible for varicella vaccination, and adults, in whom vaccination levels are low, provide evidence of the benefit of high levels of immunity in the population.

Children Hospitalized for Varicella: Complications and Cost Burden

OBJECTIVE

To evaluate the direct medical cost of hospital admissions for patients with varicella (i.e., chickenpox) to assess the cost burden of varicella from a health care perspective for ultimate use in health economics studies in Turkey.

METHODS

Records of children hospitalized with varicella at the Bakirkoy Maternity and Children's Hospital between November of 2006 and June of 2011 were reviewed. Reasons for hospitalization, types of varicella-associated complications, and direct medical cost of hospitalization were noted. Patients with underlying risk factors were excluded. Data obtained from one hospital were used to estimate the national cost of the disease.

RESULTS

During the 4.5-year study period, 234 patients were hospitalized with varicella. Of these cases, 48 (20%) children previously ill with underlying cancers or chronic diseases were excluded from the study. Ultimately, 186 previously healthy children (age range: 14 days to 159 months, median age: 14 months) were included. The main reasons for hospitalization were complications related to varicella (79%), the most frequent of which was skin and soft tissue infections, followed by neurological complications and pneumonia. The median cost of hospitalization per patient was US $283, 50% of which was attributed to medication costs. The annual cost for varicella hospitalizations in Turkey was estimated at US $396,200.

CONCLUSIONS

A significant number of healthy children are hospitalized for varicella and associated complications. Descriptions of these complications and their related costs provide important data for cost-effectiveness studies for decisions about the inclusion of the varicella vaccine in a childhood vaccination program.

Varicella outbreak in the patients during group therapy: seroprevalence in a healthcare system during breakthrough varicella occurrence

Purpose

There are different principles regarding varicella vaccination depending on social requirements. This study was performed to report a case of breakthrough chickenpox outbreak among a group of people in the healthcare center and also evaluate the seroprevalence of patients who have been managed with chronic neurological diseases in this center.

Materials and Methods

We included patients diagnosed with varicella in April 2009 as an index cases and investigated the past history for chickenpox and the varicella-specific IgG. Sixty-two patients (children) and 156 healthcare workers who may have had possible contact with the index cases were also investigated for.

Results

We investigated the seroprevalence of 62 patients not affected by the outbreak. The varicella vaccination rate in children was 90.3%. Sixty-one point three percent of all patients were seropositive and 63.6% of these patients were aged between 12 and 23 months and 87.5% were aged between 24 and 35 months. Seropositive rate was decreased for patients aged between 36 and 59 months while the seropositive prevalence has increased for patients over 5 years old. Over 90% of the adults investigated were seropositive. IgG seronegative despite vaccination was 32.1% (18 persons).

Conclusion

Breakthrough varicella outbreak can have huge impact in healthcare centers with affiliated group housing. We need to investigate vaccination status and immunogenicity according to ages and reflect appropriately on vaccination policy taking into consideration of social and medical requirements in the local area.

Validity of medical record documented varicella-zoster virus among unvaccinated cohorts

BACKGROUND

A varicella diagnosis or verification of disease history by any healthcare provider is currently accepted for determining evidence of immunity by the Advisory Committee on Immunization Practices (ACIP).

OBJECTIVE

To examine the accuracy of medical record (MR) documented varicella history as a measure of varicella-zoster virus (VZV) immunity among unvaccinated individuals born after 1980. We also assessed methods to practically implement ACIP guidelines to verify varicella history using medical records.

STUDY DESIGN

As part of a larger cross-sectional study conducted at three Philadelphia clinics from 2004-2006, we recruited 536 unvaccinated patients aged 5-19 y (birth years: 1985-2001). Varicella history was obtained from three sources: parent/patient interview, any MR documentation (sick and well visits) and MR documentation of a sick visit for varicella. All participants were tested for VZV IgG. For each source and three age groups (5-9, 10-14, 15-19 y old), positive predictive value (PPV) was calculated. Specificity of varicella history was compared between different sources using McNemar's Chi-square.

RESULTS

Among participants aged 5-9, 10-14 and 15-19 y the PPV for any MR documentation and sick visit diagnosis were 96% and 100%, 92% and 97%, and 99% and 100%, respectively. The specificity for sick visit documentation was higher than any MR documentation and patient/parent recall among all age groups; however, these differences were only statistically significant when comparing sick visit documentation to parent/patient recall for 10-14 y olds.

CONCLUSION

Sick visit documentation of varicella in the MR is an accurate predictor of varicella seropositivity and useful for confirming disease history among unvaccinated persons (birth years: 1985-2001). This method is a practical way to verify varicella history using the ACIP guidelines.

Review of the United States universal varicella vaccination program: Herpes zoster incidence rates, cost-effectiveness, and vaccine efficacy based primarily on the Antelope Valley Varicella Active Surveillance Project data

In a cooperative agreement starting January 1995, prior to the FDA's licensure of the varicella vaccine on March 17, the Centers for Disease Control and Prevention (CDC) funded the Los Angeles Department of Health Services' Antelope Valley Varicella Active Surveillance Project (AV-VASP). Since only varicella case reports were gathered, baseline incidence data for herpes zoster (HZ) or shingles was lacking. Varicella case reports decreased 72%, from 2834 in 1995 to 836 in 2000 at which time approximately 50% of children under 10 years of age had been vaccinated. Starting in 2000, HZ surveillance was added to the project. By 2002, notable increases in HZ incidence rates were reported among both children and adults with a prior history of natural varicella. However, CDC authorities still claimed that no increase in HZ had occurred in any US surveillance site. The basic assumptions inherent to the varicella cost-benefit analysis ignored the significance of exogenous boosting caused by those shedding wild-type VZV. Also ignored was the morbidity associated with even rare serious events following varicella vaccination as well as the morbidity from increasing cases of HZ among adults. Vaccine efficacy declined below 80% in 2001. By 2006, because 20% of vaccinees were experiencing breakthrough varicella and vaccine-induced protection was waning, the CDC recommended a booster dose for children and, in 2007, a shingles vaccination was approved for adults aged 60 years and older. In the prelicensure era, 95% of adults experienced natural chickenpox (usually as children)-these cases were usually benign and resulted in long-term immunity. Varicella vaccination is less effective than the natural immunity that existed in prevaccine communities. Universal varicella vaccination has not proven to be cost-effective as increased HZ morbidity has disproportionately offset cost savings associated with reductions in varicella disease. Universal varicella vaccination has failed to provide long-term protection from VZV disease.

Seroprevalence of varicella-zoster virus in the prevaccine era: a population-based study in Izmir, Turkey

PURPOSE

To determine the population-based seroprevalence of varicella zoster virus (VZV) and related risk factors in Izmir.

MATERIALS AND METHODS

A population-based household survey was conducted. A representative sample of the population older than 15 years of age was selected using multistage random sampling. A total of 2136 healthy persons participated in this cross-sectional study. The participants completed a questionnaire designed to collect data related to socio-demographic characteristics and risk factors. Blood samples were collected, and VZV-specific IgG was measured using an ELISA.

RESULTS

In total, 94.3% of individuals were seropositive for VZV. The difference between VZV seroprevalence in urban and rural populations was significant (OR: 2.6 (95% CI, 1.7-3.8)). No statistically significant differences in seropositivity were observed with respect to other sociodemographic characteristics.

CONCLUSION

A large proportion of the participants were found to be immune to VZV.

Varicella-zoster virus: Prevention through vaccination

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