Expanded spectrum of varicella disease and the need for vaccination in India

Varicella vaccine was first licensed in Japan and South Korea in 1989 for use in healthy children and was introduced in US in 1995. So far, 29 countries have adopted varicella vaccine in their universal immunization program (UIP). No Asian country, India included, has adopted the varicella vaccine as part of their UIP. The extra-cutaneous sites for VZV diseases are central nervous system and gastrointestinal tract, the expanded disease spectrum includes vasculopathy, myelitis, inflammatory bowel disease, perforated ulcers, and gastritis. The actual disease burden of varicella is not known as most of the infected individuals may not visit the physician. The amplifiable VZV DNA will not always be detectable in cerebrospinal fluid (CSF) samples in protracted illnesses such as vasculopathies, but demonstrable anti-VZV IgG in CSF has diagnostic value. The World Health Organization (WHO) position paper 2014 recommends two doses of varicella and zoster vaccines in targeted population. In India, varicella vaccine is not included in the UIP due to the cost and the belief that lifelong immunity occurs following primary infection. The expanded spectrum of VZV disease and the mounting body of evidence, however, suggest the need for both varicella and zoster vaccines in routine immunization schedule.

Low vaccine coverage and varicella outbreaks in Brazil - 2019-2022

The persistence of varicella outbreaks in Brazil has underscored the high concern with the low vaccine coverage in the last 4 years. Using publicly available data from the Brazilian Health System (SUS), this study analyzed varicella vaccine coverage and incidence trends from 2019 to 2022 in Brazilian States. Vaccine coverage decreased nationally in 2020, possibly influenced by the COVID-19 pandemic's initial phase. In Bahia State, we have the persistence of varicella with an incidence rate of 3.0 cases per 100,000 inhabitants (higher incidence compared to other States) in 2023. Under 15 months children and young children (4-6 Years old) faced the highest risk, urging the importance of vaccination. Despite a monovalent varicella vaccine being available through Brazil's National Immunization Program (NIP), Bahia fell short of achieving the ≥95 % disease control target for coverage. The study highlight the importance of vaccines to prevent some infectious diseases, as varicella, in poor tropical regions. Addressing vaccine hesitancy and misinformation, and augmenting awareness campaigns, are important to achieve and sustain high vaccine coverage over 80% as WHO guidelines to obtain a safe rate of protection for Brazilian population (Brazil's national immunization program has a target of 95% coverage).

An economic evaluation and incremental analysis of the cost effectiveness of three universal childhood varicella vaccination strategies for Ireland

BACKGROUND

The cost effectiveness of childhood varicella vaccination is uncertain, as evidenced by variation in national health policies. Within the European Economic Area (EEA), only 10 of 30 countries offer universally funded childhood varicella vaccination. This study estimates the cost effectiveness of universal childhood varicella vaccination for one EEA country (Ireland), highlighting the difference in cost effectiveness between alternative vaccination strategies.

METHODS

An age-structured dynamic transmission model, simulating varicella zoster virus transmission, was developed to analyse the impact of three vaccination strategies; one-dose at 12 months old, two-dose at 12 and 15 months old (short-interval), and two-dose at 12 months and five years old (long-interval). The analysis adopted an 80-year time horizon and considered payer and societal perspectives. Clinical effectiveness was based on cases of varicella and subsequently herpes zoster and post-herpetic neuralgia avoided, and outcomes were expressed in quality-adjusted life-years (QALYs). Costs were presented in 2022 Irish Euro and cost effectiveness was interpreted with reference to a willingness-to-pay threshold of €20,000 per QALY gained.

RESULTS

From the payer perspective, the incremental cost-effectiveness ratio (ICER) for a one-dose strategy, compared with no vaccination, was estimated at €8,712 per QALY gained. The ICER for the next least expensive strategy, two-dose long-interval, compared with one-dose, was estimated at €45,090 per QALY gained. From a societal perspective, all three strategies were cost-saving compared with no vaccination; the two-dose short-interval strategy dominated, yielding the largest cost savings and health benefits. Results were stable across a range of sensitivity and scenario analyses.

CONCLUSION

A one-dose strategy was highly cost effective from the payer perspective, driven by a reduction in hospitalisations. Two-dose strategies were cost saving from the societal perspective. These results should be considered alongside other factors such as acceptability of a new vaccine within the overall childhood immunisation schedule, programme objectives and budget impact.

Serious neurological adverse events in immunocompetent children and adolescents caused by viral reactivation in the years following varicella vaccination

Serious adverse events following vaccination include medical complications that require hospitalisation. The live varicella vaccine that was approved by the Food and Drug Administration in the United States in 1995 has an excellent safety record. Since the vaccine is a live virus, adverse events are more common in immunocompromised children who are vaccinated inadvertently. This review includes only serious adverse events in children considered to be immunocompetent. The serious adverse event called varicella vaccine meningitis was first reported in a hospitalised immunocompetent child in 2008. When we carried out a literature search, we found 15 cases of immunocompetent children and adolescents with varicella vaccine meningitis; the median age was 11 years. Eight of the children had received two varicella vaccinations. Most of the children also had a concomitant herpes zoster rash, although three did not. The children lived in the United States, Greece, Germany, Switzerland, and Japan. During our literature search, we found five additional cases of serious neurological events in immunocompetent children; these included 4 cases of progressive herpes zoster and one case of acute retinitis. Pulses of enteral corticosteroids as well as a lack of herpes simplex virus antibody may be risk factors for reactivation in immunocompetent children. All 20 children with adverse events were treated with acyclovir and recovered; 19 were hospitalised and one child was managed as an outpatient. Even though the number of neurological adverse events remains exceedingly low following varicella vaccination, we recommend documentation of those caused by the vaccine virus.

Varicella in the 21st Century

Varicella is a highly contagious disease caused by the varicella-zoster virus and has a wide range of clinical presentations. Varicella can cause mild disease in infants born to infected persons who are immunized as a result of previous vaccination or previous clinical or subclinical infection. However, varicella can also lead to severe life-threatening disease in infants, particularly for those born to nonimmunized persons. In this review, we will summarize the natural history of varicella-zoster infection in pregnant persons, infants with congenital varicella syndrome, and infants with postnatal varicella infection. We will also provide guidance about isolation recommendations and chemoprophylaxis for exposed hospitalized infants. Finally, we will describe risk factors for developing disseminated disease and review the approach to treatment of infected infants.

UK healthcare professionals' attitudes towards the introduction of varicella vaccine into the routine childhood vaccination schedule and their preferences for administration

BACKGROUND

Varicella (chickenpox) is a highly contagious disease caused by the varicella-zoster virus. Although typically mild, varicella can cause complications leading to severe illness and even death. Safe and effective varicella vaccines are available. The Joint Committee on Vaccination and Immunisation has reviewed the evidence and recommended the introduction of varicella vaccine into the UK's routine childhood immunisation schedule.

OBJECTIVES

To explore UK healthcare professionals' (HCPs) knowledge and attitudes towards varicella vaccination, its introduction to the UK routine childhood immunisation schedule, and their preferences for how it should be delivered.

DESIGN

We conducted an online cross-sectional survey exploring HCPs' attitudes towards varicella, varicella vaccine, and their preferences for delivery of the vaccine between August and September 2022 prior to the recommendation that varicella vaccine should be introduced.

PARTICIPANTS

91 HCPs working in the UK (81 % nurses/health visitors, 9 % doctors, 10 % researcher/other, mean age 48.7 years).

RESULTS

All respondents agreed or strongly agreed that vaccines are important for a child's health. However, only 58% agreed or strongly agreed that chicken pox was a disease serious enough to warrant vaccination. Gaps in knowledge about varicella were revealed: 21.0% of respondents disagreed or were unsure that chickenpox can cause serious complications, while 41.8% were unsure or did not believe chickenpox was serious enough to vaccinate against. After receiving some basic information about chickenpox and the vaccine, almost half of the HCPs (47.3%) in our survey would prefer to administer the varicella vaccine combined with MMR.

CONCLUSIONS

Given the positive influence of HCPs on parents' decisions to vaccinate their children, it is important to understand HCPs' views regarding the introduction of varicella vaccine into the routine schedule. Our findings highlighted areas for training and HCPs' preferences which will have implications for policy and practice when the vaccine is introduced.

Varicella outbreak at nursery school under routine immunization in Japan in 2017 and 2018 and vaccine effectiveness

BACKGROUND

In Japan, routine administration to one-year-old children of two-dose immunization for varicella was introduced in October 2014. Object The object of this study was to report outbreaks of varicella under routine immunization at a nursery school and in its surrounding area using data of surrounding areas from the (Nursery) School Absenteeism Surveillance System. Then, we measured the effectiveness of routine two-dose immunization for varicella to onset. We tentatively assessed its severity in a nursery school.

METHOD

The study period extended from April 2017 through March 2018. The study area comprised Nursery school B and other nursery schools, and elementary and junior high schools in City A. Subjects in Nursery school B were 120 children. We analyzed vaccine effectiveness (VE) as an observational study and assessed severity using Fisher's exact test. We also assessed VE for severity using linear regression. Severity was defined as the length of nursery school absence attributable to varicella infection.

RESULTS

During the one month preceding a period of two weeks before the initial case at Nursery school B, there were 16 cases of varicella infection in nursery schools, 45 cases in elementary schools, and one case in junior high schools in City A. For children who had received one vaccine dose or more, VE was 48.1% for all ages and 49.2% among children three years old and older. No significant VE against infection was found. Vaccination using one dose or more can reduce severity significantly.

DISCUSSION AND CONCLUSION

Because many nursery school children who had received two doses of vaccine were infected, VE was estimated as low in the nursery school and not significant. Although VE for severity with more than one dose was confirmed, a second dose might not reduce severity compared to one dose.

Epidemiological Characteristics of Varicella in Anhui Province, China, 2012-2021: Surveillance Study

BACKGROUND

Varicella is a mild, self-limited disease caused by varicella-zoster virus (VZV) infection. Recently, the disease burden of varicella has been gradually increasing in China; however, the epidemiological characteristics of varicella have not been reported for Anhui Province.

OBJECTIVE

The aim of this study was to analyze the epidemiology of varicella in Anhui from 2012 to 2021, which can provide a basis for the future study and formulation of varicella prevention and control policies in the province.

METHODS

Surveillance data were used to characterize the epidemiology of varicella in Anhui from 2012 to 2021 in terms of population, time, and space. Spatial autocorrelation of varicella was explored using the Moran index (Moran I). The Kulldorff space-time scan statistic was used to analyze the spatiotemporal aggregation of varicella.

RESULTS

A total of 276,115 cases of varicella were reported from 2012 to 2021 in Anhui, with an average annual incidence of 44.8 per 100,000, and the highest incidence was 81.2 per 100,000 in 2019. The male-to-female ratio of cases was approximately 1.26, which has been gradually decreasing in recent years. The population aged 5-14 years comprised the high-incidence group, although the incidence in the population 30 years and older has gradually increased. Students accounted for the majority of cases, and the proportion of cases in both home-reared children (aged 0-7 years who are not sent to nurseries, daycare centers, or school) and kindergarten children (aged 3-6 years) has changed slightly in recent years. There were two peaks of varicella incidence annually, except for 2020, and the incidence was typically higher in the winter peak than in summer. The incidence of varicella in southern Anhui was higher than that in northern Anhui. The average annual incidence at the county level ranged from 6.61 to 152.14 per 100,000, and the varicella epidemics in 2018-2021 were relatively severe. The spatial and temporal distribution of varicella in Anhui was not random, with a positive spatial autocorrelation found at the county level (Moran I=0.412). There were 11 districts or counties with high-high clusters, mainly distributed in the south of Anhui, and 3 districts or counties with high-low or low-high clusters. Space-time scan analysis identified five possible clusters of areas, and the most likely cluster was distributed in the southeastern region of Anhui.

CONCLUSIONS

This study comprehensively describes the epidemiology and changing trend of varicella in Anhui from 2012 to 2021. In the future, preventive and control measures should be strengthened for the key populations and regions of varicella.

Herpes zoster infection in pregnancy: features and consequences

Herpes (varicella) zoster (HZ) infection occurs in 4 people per 1000 in the general US population (irrespective of prior varicella infection and vaccination status) each year and has been the subject of scientific inquiry for decades. The consequences of infection are myriad and may depend on the dermatome of involvement as well as host factors such as age, comorbidities, prior treatment or immunization, and immunologic status. Pregnancy is associated with an altered immune and hormonal status in the mother. While maternal HZ infection during pregnancy is not uncommon, the implications for both mother and child are not well established, although multiple studies of perinatal maternal HZ infection suggest no intrauterine transmission to the fetus. We review the current literature on herpes zoster infection in pregnancy, including epidemiology, diagnosis, potential immunologic sequelae, and strategies for prevention and treatment.

Effectiveness of the combined MMRV Priorix-Tetra™ vaccine against varicella in a large Italian region: A case-control study

Priorix-Tetra™ (MMRV GlaxoSmithKline Biologicals' vaccine) was developed based on the existing measles-mumps-rubella and varicella vaccines. In this study, we aimed to estimate the effectiveness of the combined measles-mumps-rubella-varicella Priorix-Tetra™ vaccine against varicella in real-world conditions. We conducted a post-marketing retrospective case-control study in the Apulia region of Italy in children aged 1-9 years born between January 1, 2008 and December 31, 2016. We assessed the effectiveness against varicella of all grades of severity (including hospitalisation) and against hospitalisation for varicella of a single and two doses of Priorix-Tetra™. Moreover, we also assessed effectiveness of monovalent varicella (monovalent-V) vaccine and any varicella vaccines. Vaccine effectiveness was calculated as (1-OR) x 100. We introduced demographic variables in the model to adjust Vaccine effectiveness (aVE) by potential confounders (sex and year of birth). We recorded 625 varicella cases and matched them with 1,875 controls. Among 625 cases, 198 had received a single MMRV dose, 10 two MMRV doses, 46 a single monovalent-V dose, none two monovalent-V doses; four a monovalent-V as first dose and MMRV as second dose, and one a MMRV as first dose and monovalent-V as second dose; 366 cases were not vaccinated. The aVE against varicella of all grades of severity was 77.0% and 93.0% after a single dose and after two doses of MMRV, respectively. The aVE against varicella of all grades was 72.0% after a single dose of monovalent-V vaccine. The aVE against varicella of all grades of severity was 76.0% after a single dose and 94.0% after two doses of any varicella vaccine. The aVE against varicella hospitalisation was 96% after a single dose of any varicella vaccine. Priorix-Tetra™ showed to be an effective vaccine and the two-dose schedule should be recommended to optimise immunisation programmes. A single dose was able to provide protection against varicella hospitalisation.

Vaccine-preventable diseases: Immune response in a large population of healthcare students

BACKGROUND

Students in medicine and other health professions are exposed to numerous occupational hazards, primarily biological hazards, during their academic careers at university. The aim of the present study was to investigate the seroprevalence characteristics of anti-HBsAg, anti-Measles, anti-Mumps, anti-Rubella and anti-Varicella IgG antibodies in healthcare students of a large teaching hospital in Rome.

METHODS

To accomplish the study's aims, antibody serology data were gathered from students of Medicine and Surgery, Dentistry, and Health Professions at the Catholic University of the Sacred Heart (Rome Campus) during their first Health Surveillance visit, that took place from 2013 to 2023.

RESULTS

Our study sample included 2523 students, 44.4 % were protected against Hepatitis B, 87.3 % against measles, 85.5 % against mumps, 94.6 % rubella and 95.2 % against varicella. Differences in antibody coverage between age groups were statistically significant (p < 0.001), except for mumps. It found a lower probability of having seronegative anti-HBVs with an older date since the presumed primary vaccination.

CONCLUSION

In our sample, seropositivity rate against vaccine-preventable diseases, especially for Hepatitis B, was often inadequate to prevent possible biological risks connected with the activities carried out on the ward.

Position statement on infection screening, prophylaxis, and vaccination of pediatric patients with rheumatic diseases and immunosuppressive therapies, part 3: precautions in situations of surgery, fever, and opportunistic infections

The objective of this study is to provide practical recommendations on the management of pediatric patients with immune-mediated rheumatic diseases receiving immunosuppressive therapies. The recommendations specifically address the cases of surgery, fever, and opportunistic infections (varicella, herpes-zoster, tuberculosis, invasive fungal disease). A qualitative approach was applied. A narrative literature review was performed via Medline. Primary searches were conducted using MeSH terms and free text to identify publications on infections and vaccinations in pediatric patients with immune-mediated rheumatic diseases receiving immunosuppressive therapies. The results were presented and discussed in a nominal group meeting, comprising a committee of 12 pediatric rheumatologists from the Infection Prevention and Treatment Working Group of the Spanish Society of Pediatric Rheumatology. Several recommendations were generated. A consensus procedure was implemented via a Delphi process; this was extended to members of the Spanish Society of Pediatric Rheumatology and Spanish Society of Pediatric Infectious Disease of the Spanish Association of Pediatrics. Participants produced a score ranging from 0 (totally disagree) to 10 (totally agree). Agreement was defined as a vote ≥ 7 by at least 70% of participants. The literature review included more than 400 articles. Overall, 63 recommendations (19 on surgery, fever, and opportunistic infections) were generated and voted by 59 pediatric rheumatologists and other pediatric specialists. Agreement was reached for all 63 recommendations. The recommendations on special situations cover management in cases of surgery, fever, and opportunistic infections (varicella, herpes-zoster, tuberculosis, and invasive fungal disease).  Conclusions: Hereby, we provided consensus and updated of recommendations about the management of special situations such as surgery, fever, and opportunistic in children with immune-mediated rheumatic diseases receiving immunosuppressive therapies. Several of the recommendations depend largely on clinical judgement and specific balance between risk and benefit for each individual and situation. To assess this risk, the clinician should have knowledge of the drugs, the patient's previous situation as well as the current infectious disease, in addition to experience. What is Known: • Infectious diseases and related complications are a major cause of morbidity and mortality in patients with immune-mediated rheumatic diseases. • Information on how to manage the treatment in situations of fever, opportunistic infections, and surgery in children is limited, and guidelines for action are often extrapolated from adults. What is New: • In the absence of strong evidence, a literature review and a Delphi survey were conducted to establish a series of expert recommendations that could support the clinical practice, providing a practical and simple day-to-day approach to be used by pediatric rheumatologists.

Post-Exposure Prophylaxis for Varicella-Zoster Virus Exposure in High-Risk Children

BACKGROUND

Post-exposure prophylaxis (PEP) with varicella immunoglobulin is recommended to minimize risk of varicella complications for high-risk children. However, providers frequently use alternatives like acyclovir or intravenous immunoglobulin.

METHODS

A retrospective cohort study was conducted of PEP for varicella in children from January 2009 to December 2019. Data were provided by 47 children's hospitals who participate in the Pediatric Health Information Systems database. Patients with clinical encounters for varicella exposure were reviewed. Choice of varicella PEP regimens, including differences by underlying condition and institution, and incidence of varicella disease were determined.

RESULTS

A total of 1704 patients with first clinical encounters for varicella met inclusion criteria. Of these patients, 509 (29.9%) were prescribed PEP after varicella exposure, and 65 (3.8%) ultimately had a subsequent encounter for varicella disease. Of 509 patients who received PEP, acyclovir was most frequently prescribed (n = 195, 38.3%), followed by varicella immunoglobulin (n = 146, 28.7%), IVIG (n = 115, 22.6%), and combination therapy (n = 53, 10.4%). The highest proportion of varicella immunoglobulin use (10/20, 50%) was amongst children with diagnoses of rheumatological/gastrointestinal conditions. The highest proportion of acyclovir use (29/684, 4.2%) was amongst children with diagnoses of oncology/stem cell transplant conditions. The proportion of patients who subsequently had clinical encounters for varicella disease was highest for Acyclovir (30/195, 15.4%) followed by varicella immunoglobulin (5/146, 3.4%), combination therapy (2/53, 3.8%), and intravenous immunoglobulin alone (0/115) (P < .0001).

CONCLUSIONS

Varicella PEP in high-risk children was highly varied among children's hospitals. In our dataset, use of acyclovir was associated with a higher rate of subsequent encounters for Varicella disease.

Measles, mumps, rubella and varicella antibodies among international and domestic university students

BACKGROUND

Vaccine-preventable infections are generally well controlled in Australia. However, gaps in immunity can lead to outbreaks and are important to identify. Young adults are a highly mobile population and a potential source of imported infections. We aimed to evaluate anti- measles, mumps, rubella and varicella (MMR&V) IgG seroprevalence and explore factors relating to antibody seropositivity.

METHODS

A cross-sectional online survey was conducted among students from a large Australian university to collect demographic, vaccination, infection and travel characteristics. Blood samples were collected to measure MMR&V seroprevalence. Logistic regression was used to identify factors associated with seropositivity.

RESULTS

Among 804 university students, seroprevalence (positive or equivocal) for measles was 82.3% (95% CI 79.6-84.8%), mumps 79.5% (95% CI 76.7-82.3%), rubella 91.5% (95% CI 89.6-93.5%) and varicella 86.2% (95% CI 84.1-88.8%), with 452 (56.2%, 95% CI 52.8-59.6) seropositive to all four viruses. Varicella seropositivity was highest in the older birth cohort (born 1988-1991). Measles seropositivity was higher for international students compared to domestic students. Among international students, mumps seroprevalence was significantly lower than measles and rubella seroprevalence. International travel in the previous 12 months was reported by 63.1% of students, but only 18.2% of travellers reported seeking pre-travel health advice prior to most recent international travel.

CONCLUSIONS

Overall, this study suggests immunity to MMR&V is sub-optimal. We found the university student population to be highly mobile and unlikely to seek pre-travel advice; thus, they are a potential source of infection importation. The implementation of university immunization policies could address the gaps identified and our findings can inform the development of targeted vaccination campaigns.

Immunogenicity and safety of a live-attenuated varicella vaccine in a healthy population aged 13 years and older: A randomized, double-blind, controlled study

OBJECTIVES

Vaccines for prevention against varicella are important for adolescents and adults, who have an increased risk of severe varicella. This study aimed to evaluate the immunogenicity and safety of a two-dose immunization schedule of a live-attenuated varicella vaccine (VarV) manufactured by Sinovac (Dalian) in healthy adolescents and adults.

METHODS

A randomized, double-blind, controlled clinical trial was conducted in healthy population aged ≥ 13 years old in China. Participants in block 1 were randomly assigned (1:1) to receive two doses of either the test vaccine or an active control vaccine, administered 4, 6 or 8 weeks apart. Participants in block 2 were randomly assigned (2:1) to receive two doses of test vaccine or placebo, administered 10 weeks apart. The primary immunogenicity endpoint was the seroconversion rates and GMTs of varicella zoster virus (VZV) antibodies measured by fluorescent-antibody-to-membrane-antigen (FAMA) 4 weeks post-immunization. The primary safety endpoint was the incidence of adverse reactions within 4 weeks after each dose.

RESULTS

A total of 2398 participants were enrolled. The seroconversion rates of VZV antibodies were 79.55 % in the test group and 76.41 % in the active control group respectively 4 weeks after two doses of pooled schedule, with the difference of 3.14 % (95 %CI: -0.69 %, 6.97 %). The GMTs were 1:162.07 and 1:160.04 respectively, with the ratio of 1.013 (95 %CI: 0.910, 1.127). Both the seroconversion rates and GMTs reached the prespecified non-inferiority criteria. Two-dose schedule with an interval of 10 weeks could also induce high immune responses, with a seroconversion rate of 83.22 % and a GMT of 1:160.38 in the test group. Safety profiles were similar among the test group, active control group and placebo group.

CONCLUSION

VarV, manufactured by Sinovac (Dalian), demonstrated higher immune response and better flexibility in the immunization schedule among heathy population aged 13 years and older, without increased safety risk.

Parental perceptions of chickenpox and the varicella vaccine: A qualitative systematic review

BACKGROUND

In countries where varicella vaccination is not on the routine childhood immunisation schedule, such as those in the United Kingdom (UK), chickenpox is an almost universal disease of childhood. Chickenpox can cause serious complications, particularly in infants, pregnant women, and the immunocompromised. In November 2023 the varicella vaccine was recommended for inclusion in the UK routine childhood immunisation schedule. Successful rollout of the vaccine may be hindered by parental concerns about vaccine safety and efficacy, and perceptions of chickenpox as a mild illness.

OBJECTIVE

To examine parental perceptions of chickenpox and varicella vaccination, which may be crucial to effective vaccination campaigns.

DESIGN

Qualitative systematic review and thematic analysis.

METHODS

Six electronic databases were systematically searched for studies published between 2016 and 2023: CINAHL, EMBASE, MEDLINE, PsycInfo, PubMed, and Web of Science. The included studies were appraised against the Critical Appraisal Skills Program checklist for qualitative studies. Thematic analysis was used to analyse qualitative data, through the development of themes.

RESULTS

22 articles were included in this review, and five themes identified: perceptions that chickenpox is a mild illness, that parents have concerns about varicella vaccine efficacy and safety, a notion of natural immunity as superior, social determinants of health influence vaccine decision making, and vaccination is overwhelming perceived as a parental decision.

CONCLUSIONS

Whilst some parents displayed an acceptance and willingness to vaccinate against chickenpox, many expressed concerns, and perceived chickenpox as a routine unworrying childhood illness. Analysis demonstrated a knowledge gap in understanding UK parental opinions regarding chickenpox and varicella vaccination, highlighting the need for research in this area, particularly given ongoing reconsideration for inclusion in the UK vaccination schedule.

REGISTRATION

The review was registered on PROSPERO, registration ID CRD42021236120.

Immunity Rates of Live Viral Vaccines in Pediatric Renal Transplant Candidates: A Single-Center Experience

OBJECTIVES

Solid-organ transplant recipients are at an increased risk of severe infections due to their immunosuppressed state. Despite the recommendation of routine screening and vaccination before transplant to mitigate this danger, vaccination rates in these patients are still below desirable levels. We aimed to investigate the prevalence of positive antibody rates for measles, mumps, rubella, and varicella among children who are candidates for renal transplant.

MATERIALS AND METHODS

This retrospective study was conducted at a single center and included 144 pediatric kidney transplant patients for the past 7 years. We reviewed the medical records of all participants to evaluate their serologic status for measles, mumps, rubella, and varicella viruses before kidney transplant.

RESULTS

In this study, 144 pediatric kidney transplant candidates (mean age 11.5 years, 56.9% male) were enrolled, and the most frequent causes of the chronic renal disease were congenital anomalies of the kidney and urinary tract and glomerular diseases (32.6%). Seropositivity rates for measles, mumps, rubella, and varicella were 59.0%, 31.9%, 46.5%, and 43.6%, respectively, and all patients who tested negative for antibodies were vaccinated before transplant. Younger age at transplant (OR = 0.909, 95% CI = 0.840-0.923; P = .017) and congenital anomalies of the kidney and urinary tract (OR = 3.46, 95% CI = 1.1548-7.735; P = .002) were significantly associated with increased measles seropositivity, although no significant associations were observed for the other viruses.

CONCLUSIONS

We observed lower seropositivity rates for measles, mumps, rubella, and varicella in pediatric kidney transplant patients versus healthy children and other previous studies. It is essential to address these suboptimal rates to protect the health of these vulnerable patients. Future research should focus on targeted interventions to improve vaccination rates and outcomes in this population.

Case report: Hospital-acquired chickenpox in a healthcare setting

Chickenpox (varicella) is a rare occurrence in healthcare settings in the USA, but can be transmitted to healthcare workers (HCWs) from patients with herpes zoster who, in turn, can potentially transmit it further to unimmunized, immunosuppressed, at-risk, vulnerable patients. It is uncommon due to the inclusion of varicella vaccination in the recommended immunization schedule for children and screening for varicella immunity in HCWs during employment. We present a case report of hospital-acquired chickenpox in a patient who developed the infection during his prolonged hospital stay through a HCW who had contracted chickenpox after exposure to our patient's roommate with herpes zoster. There was no physical contact between the roommates, but both patients had a common HCW as caregiver. The herpes zoster patient was placed in airborne precautions immediately, but the HCW continued to work and have physical contact with our patient. The HCW initially developed chickenpox 18 days after exposure to the patient with herpes zoster, and our patient developed chickenpox 17 days after the HCW. The timeline and two incubation periods, prior to our patient developing chickenpox, indicate transmission of chickenpox in the HCW from exposure to the herpes zoster patient and subsequently to our patient. The case highlights the potential for nosocomial transmission of chickenpox (varicella) to unimmunized HCWs from exposure to patients with herpes zoster and further transmission to unimmunized patients. Verification of the immunization status of HCWs at the time of employment, mandating immunity, furloughing unimmunized staff after exposure to herpes zoster, and postexposure prophylaxis with vaccination or varicella zoster immunoglobulin (Varizig) will minimize the risk of transmission of communicable diseases like chickenpox in healthcare settings. Additionally, establishing patients' immunity, heightened vigilance and early identification of herpes zoster in hospitalized patients, and initiation of appropriate infection control immediately will further prevent such occurrences and improve patient safety.

This is a case report of a varicella-unimmunized 31-year-old patient who developed chickenpox during his 80-day-long hospitalization. He had different roommates during his long hospital stay but had no physical contact with them and neither had visitors. On most days, the same HCW rendered care to him and his roommates. One of the patient’s roommates was found to have herpes zoster and was immediately moved to a different room with appropriate infection prevention measures. The HCW is presumably unimmunized to varicella and sustained significant exposure to the patient with herpes zoster during routine patient care which involved significant physical contact. The HCW was not furloughed, assessed for immunity, or given postexposure prophylaxis (PEP). The HCW had continued contact with our patient as part of routine care. On day 18, after exposure to the patient with herpes zoster, the HCW developed chickenpox. 17 days thereafter, our patient developed chickenpox. The time interval of chickenpox infection in the HCW after one incubation period after exposure to the patient with herpes zoster followed by a similar infection of chickenpox in our patient after another incubation period suggests the spread of varicella zoster virus (VZV) from the herpes zoster patient to the HCW and further from the HCW to our patient. Assessing the immunity of HCWs to varicella at the time of employment, ensuring only HCWs with immunity take care of herpes zoster and varicella patients, furloughing unimmunized exposed HCWs, offering PEP, and documentation of patients’ immunity to varicella at the time of hospital admission could help prevent VZV transmission in hospital settings. This is an attempt to publish this novel case due to its high educational value and relevant learning points.

Varicella Zoster vaccination in hemodialysis patients: The state of the art

Varicella Zoster Virus (VZV) infection is a common childhood exanthematous disease, which in adults and immunocompromised people may result in severe neurologic complications. Up to one-third of infected subjects may have VZV clinical reactivation particularly if immunocompromised. Patients affected by end-stage renal disease on hemodialysis present immunodepression that contributes to their higher incidence of VZV infections and reactivation. While antiviral treatment in these patients shows low efficacy, the prevention of VZV through vaccination avoids the primary infection and the risk of reactivation. Two VZV vaccines are currently available: the live attenuate Zoster Vaccine (LZV) and a Recombinant Zoster Vaccine (RZV), with the latter appearing to provide greater efficacy. Given the higher incidence of VZV infection and reactivation, the lesser response to antivirals and the lower impact of VZ vaccine in hemodialysis patients in terms of side effects, a higher diffusion of VZV vaccination should be promoted by nephrologists in these patients in particular in those with future transplant opportunities.

The impact of varicella vaccination: A 2005-2019 interrupted time series analysis

Varicella is an acute, highly contagious disease in susceptible individuals and is preventable through vaccination. This study aimed to determine the impact of varicella vaccination on hospitalizations and complications at a pediatric reference hospital in Panama before and after the vaccine introduction. This descriptive ecological study analyzed clinical records of patients diagnosed with varicella through a retrospective and interrupted time series analysis. An autoregressive integrated moving average model was built to compare the incidence rates observed after vaccination with those expected rates derived from the model. A statistical model was fitted to the observed interrupted time series data by regression and used to predict future trends. The mean difference in varicella hospital discharges before and after the introduction of the varicella vaccine was 47%. The rate of hospitalizations for varicella decreased to 52.3%. A declining trend in varicella hospitalizations was observed from 2015 after vaccine introduction in 2014. Complications in vaccinated patients were secondary skin and soft tissue infection, possibly due to bacterial superinfection. The impact of varicella vaccination on reducing varicella hospital discharges reported at a pediatric reference hospital in Panama was confirmed.

Healthcare resource use and costs of varicella and its complications: A systematic literature review

Varicella is a highly contagious disease caused by the varicella zoster virus (VZV). While the disease is usually mild, severe complications can occur requiring costly hospitalization. A thorough understanding of the healthcare resource use (HCRU) and costs of varicella is needed to inform health-economic models of preventive strategies. A systematic literature review was carried out to retrieve relevant publications between 1999 and 2021, reporting HCRU and cost outcomes for varicella and its complications. Data were extracted and stratified according to pre-specified age groups and complication categories. Costs were re-based to a $US2020 footing using both purchasing power parity and the medical component of consumer price indexes. Data were summarized descriptively due to high heterogeneity in study design and outcome reporting. Forty-four publications fulfilled the inclusion and exclusion criteria of which 28 were conducted in Europe, 6 in Middle East and Asia, 5 in South America, 3 in North America, and 2 in multiple regions. Primary healthcare visits accounted for 30% to 85% of total direct costs. Hospitalization costs varied between $1,308 and $38,268 per episode depending on country, complication type, and length of stay, contributing between 2% and 60% to total direct costs. Indirect costs, mostly driven by workdays lost, accounted for approximately two-thirds of total costs due to varicella. The management of varicella and related complications can lead to substantial HCRU and costs for patients and the healthcare system. Additional research is needed to further characterize the varicella-associated economic burden and its broader impact from a societal standpoint.

[Epidemiological characteristics of public health emergency events of varicella in China, 2006-2021]

Objective: To understand the epidemiological characteristics of public health emergency events (PHEE) of varicella in China from 2006 to 2021 and related response performances. Methods: The data of varicella PHEE in 31 provinces of China from 2006 to 2021 were collected through the Public Health Emergency Management Information System, Microsoft Excel 2019 software and SPSS 26.0 statistical software were used to conduct descriptive epidemiological, statistical analysis on the time, area, location distribution, scale and epidemic management. Results: A total of 11 443 PHEE involving 341 048 related cases were reported from 2006 to 2021, with an annual attack rate of 1.78%-3.80% and a total attack rate of 2.33% (341 048/14 624 042). The number of PHEE and related cases of varicella decreased from 1 107 (35 349) in 2007 to 262 (6 884) in 2012 (Z=-2.40, P<0.001), then increased year by year to 1 318 (42 649) in 2019 (Z=2.58, P<0.001), with a significant decline since 2020. The varicella PHEE in China presents the seasonal characteristics,the peak is from April to June and from October to December, respectively. The sub-peak of varicella PHEE in eastern China generally appears 1-2 months earlier than in central and western China. Varicella PHEE reports are mainly distributed in eastern China, the attack rate is relatively high in western China, school-reported varicella PHEE was 88.26% of the total reports (10 099/11 443). The epidemic scale of varrcella PHEE typically range from 10 to 29 cases per year among the given outbreaks. The M (Q1, Q3) of average number of cases, average duration, and average reporting interval of PHEE were 23 (16,35), 20 (14, 26) days, and 9 (5,19) days, respectively, and the reporting interval was positively correlated with the duration (r=0.854, P<0.001). Conclusions: The varicella PHEE in China from 2006 to 2021 has not been effectively controlled. Schools are the key places to prevent and control varicella PHEE. Improving the sensitivity of varicella PHEE monitoring, strengthening the timely disposal of varicella epidemic, and promoting varicella vaccination are effective measures to prevent and control varicella PHEE.

Assessing the impact of chickenpox and shingles vaccination using intermittent enhanced surveillance in Queensland, Australia

INTRODUCTION

Chickenpox and shingles are vaccine preventable diseases caused by varicella-zoster virus (VZV). Chickenpox is more common in children before adolescence and shingles among ≥50 years of age. With this study we aimed to determine changes in VZV epidemiology following chickenpox and shingles vaccine introduction in Queensland.

METHODS

This case series study used notified cases of VZV infection in Queensland from January 2010 to December 2021. In Queensland, VZV notifications are received as mostly clinically unspecified cases from pathology laboratories. Intermittent enhanced surveillance was conducted using clinician follow up to determine chickenpox and shingles clinical presentation, and we then analysed these by age-group, time period, and within vaccine eligible cohorts.

RESULTS

Of the 87,759 VZV notifications received, 70 % (n = 61,298) were notified as unspecified, followed by 23 % shingles (n = 19,927), and 7 % chickenpox (n = 6,534). Over the study period, the percent change in total notifications adjusted by age and sex was estimated to be an increase of 5.7 % (95 % CI 4.9-6.4) each year. The chickenpox notifications fell sharply at 18 months of age (eligible for chickenpox vaccine) with the rate being 57 % and 36 % lower among those aged 18-23 months compared to <12 and 12-17 months of age, respectively. Assuming all cases aged 60 years and older were shingles, notification rates of shingles decreased by 12-22 % among 70-79 years old (eligible for shingles vaccination) over the years 2017-2021 after vaccine introduction in 2016.

CONCLUSION

The VZV notification rate has increased over time in Queensland. Impact of chickenpox and shingles vaccines funded under National Immunisation Program is seen with a decline in notification rates among age-specific cohorts eligible to receive the vaccines under the program. Introduction of a second childhood dose chickenpox vaccine and more effective recombinant shingles vaccine may further improve the impact of the vaccination program.

Parent and healthcare provider views of live varicella vaccination of pediatric solid organ transplant recipients

BACKGROUND

Live attenuated varicella vaccine (LAVV) has historically been contraindicated in children who are immunocompromised due to solid organ transplant (SOT) because of safety concerns. Recently, clinical guidelines were developed that support post-transplant varicella vaccination in selected SOT recipients based on emerging evidence of LAVV safety. This qualitative study sought to explore barriers and facilitators to implementing the new guidelines, as well as acceptability of LAVV among healthcare providers (HCPs) and parents.

METHODS

HCPs and parents of transplant recipients were recruited from four sites using purposive sampling. Data from semi-structured interviews were analyzed using an Interpretive Description approach that incorporated data from the interviews, academic knowledge and clinical experience, and drew from Grounded Theory and Thematic Analysis. The theoretical framework used was Adaptive Leadership.

RESULTS

Thirty-four participants (16 HCPs and 18 parents) were included in the analysis. Parents developed skills in adaptive leadership that included strategies to protect their child against infectious diseases. Foundational information that live vaccines were absolutely contraindicated post-transplant "stuck" with parents and led them to develop strategies other than vaccination to keep their child safe. Some parents struggled to understand that information previously presented as a certainty (contraindication of LAVV) could change. Their approach to adaptive leadership informed their appraisal of the new vaccination guidelines and willingness to accept vaccination.

CONCLUSIONS

HCPs should adopt a family-centered approach to communicating changing guidelines that considers parents' approach to adaptive leadership and discusses the changing nature of medical evidence. Trust between HCPs and parents can facilitate these conversations.

Maternal varicella antibodies in children aged less than one year: Assessment of antibody decay

OBJECTIVES

To investigate maternal antibody levels to varicella in infants <12 months of age in Ontario, Canada.

STUDY DESIGN

In this study, we included specimens from infants <12 months of age, born at ≥37 weeks gestational age, who had sera collected at The Hospital for Sick Children (Toronto, Canada) between 2014-2016. We tested sera using a glycoprotein-based enzyme-linked immunosorbent assay (gpELISA). We measured varicella susceptibility (antibody concentration <150mIU/mL) and mean varicella antibody concentration, and assessed the probability of susceptibility and concentration between one and 11 months of age using multivariable logistic regression and Poisson regression.

RESULTS

We found that 32% of 196 included specimens represented infants susceptible to varicella at one month of age, increasing to nearly 80% at three months of age. At six months of age, all infants were susceptible to varicella and the predicted mean varicella antibody concentration declined to 62 mIU/mL (95% confidence interval 40, 84), well below the threshold of protection.

CONCLUSIONS

We found that varicella maternal antibody levels wane rapidly in infants, leaving most infants susceptible by four months of age. Our findings have implications for the timing of first dose of varicella-containing vaccine, infection control measures, and infant post-exposure prophylaxis recommendations.

Trends in age-specific varicella incidences following the introduction of the general recommendation for varicella immunization in Germany, 2006-2022

BACKGROUND

In Germany, general childhood varicella vaccination has been recommended since 2004. A feared effect of low vaccination coverage is a possible shift in incidence from children to teenagers and young adults who are at higher risk of severe outcomes. If true, this shift would possibly necessitate changes to the national immunization strategy. We aimed to evaluate the effects of the general vaccination recommendation on age-specific varicella incidences in Germany in general and examine specifically whether a shift from children to teenagers (15 to 19 years) has occurred.

METHODS

Trends in age-specific incidences were evaluated using triangulation with the following datasets: national mandatory notification data (N) (2014-2022), billing data of the statutory health insurance associations (I) (2009-2017) and data from a doctor's sentinel system (S) (2006-2017). Similar clinical case definitions were used in N and S, while I used ICD-10-codes. Age groups were stratified as available in all three systems. Incidences per year were calculated based on the total population (N), the number of statutory health insured (I), and extrapolated from S to the total population.

RESULTS

During all years of observation, age-specific incidences have dropped significantly across all age-groups for S und I. The age groups (under 10 years) with initially highest incidences were the ones with the strongest reductions (under 1 year: -90%, 1-4 years: -95.5%, 5-9 years: -89.2% for S; -67.7%, -78%, -79.3% for I). A single 53.1% increase in the low incidence in S among 15-19-year olds observed in 2017 compared to 2016 could not be confirmed in N or I. Increases in incidences during the first two years of N are probably due to improved notification behaviour over these years. In 2019, all age-specific incidences increased (N), with 15 to 19-year olds showing the highest relative increase (28.2%).

CONCLUSIONS

Since the introduction of the general vaccine recommendation against varicella, incidences across all age-groups have declined significantly. Available data indicate no evidence for a shift in disease incidence to older age groups. Every incidence increase beyond childhood age should however be followed up closely. So far, children and adolescents have both benefitted from the current vaccination strategy.

Live vaccines following intravenous immunoglobulin for Kawasaki disease: Are we vaccinating appropriately?

AIM

Australian and New Zealand guidelines recommend that live vaccines be postponed for 11 months after treatment of Kawasaki disease (KD) with intravenous immunoglobulin (IVIG). We aimed to describe patterns of live-vaccine administration after KD treatment, focusing on the measles-mumps-rubella/measles-mumps-rubella-varicella (MMR/MMRV) vaccines, and to compare real-world practice with current recommendations.

METHODS

We combined data from inpatient Electronic Health Records and the Australian Immunisation Register for all children who received IVIG for the treatment of KD under the age of 5 years at two Australian tertiary children's hospitals over a 12-year period. Children who received IVIG <11 months before a scheduled MMR/MMRV were deemed 'at risk' of breaching the guidelines, and those whose subsequent vaccination occurred <11 months after the IVIG were deemed to have 'breached' the guidelines.

RESULTS

Of those at risk, three-quarters (76%) breached the guidelines for their first MMR/MMRV. Findings were similar (50%-80%) for the second MMR/MMRV dose.

CONCLUSIONS

The majority of Australian children treated for KD with IVIG may not be optimally protected by MMRV vaccination. Immunisation systems should address this avoidable risk.

Safety and immunogenicity of the live-attenuated varicella vaccine in pediatric solid organ transplant recipients: A systematic review and meta-analysis

This study aimed to synthesize the available evidence on the immunogenicity, safety, and effectiveness of live-attenuated varicella vaccine in solid organ transplant recipients. Medline and EMBASE were searched using predefined search terms to identify relevant studies. The included articles reported varicella vaccine administration in the posttransplant period in children and adults. A pooled proportion of transplant recipients who seroconverted and who developed vaccine-strain varicella and varicella disease was generated. Eighteen articles (14 observational studies and 4 case reports) were included, reporting on 711 transplant recipients who received the varicella vaccine. The pooled proportion was 88.2% (95% confidence interval 78.0%-96.0%, 13 studies) for vaccinees who seroconverted, 0% (0%-1.2%, 13 studies) for vaccine-strain varicella, and 0.8% (0%-4.9%, 9 studies) for varicella disease. Most studies followed clinical guidelines for administering live-attenuated vaccines, with criteria that could include being at least 1 year posttransplant, 2 months postrejection episode, and on low-dose immunosuppressive medications. Varicella vaccination in transplant recipients was overall safe in the included studies, with few cases of vaccine-strain-induced varicella or vaccine failure, and although it was immunogenic, the proportion of recipients who seroconverted was lower than that seen in the general population. Our data support varicella vaccination in select pediatric solid organ transplant recipients.

Disseminated vaccine-induced varicella infection in a kidney transplant recipient

A 33-year-old kidney transplant (KT) recipient presented with a disseminated pruritic, painful, vesicular rash and hepatitis 3 weeks after receiving a varicella vaccine (VAR). A skin lesion biopsy sent to the Centers for Disease Control and Prevention for genotyping confirmed vaccine-strain varicella-zoster virus (VZV) (Oka strain; vOka). The patient was successfully treated with intravenous acyclovir during a prolonged hospital stay. This case supports the contraindication of VAR in adult KT recipients and highlights the potential for severe illness when used in this population. Optimally, VZV-seronegative KT candidates should receive VAR before starting immunosuppressive medications. If this opportunity is missed, the recombinant varicella-zoster vaccine might be considered following transplantation as it is already recommended to prevent herpes zoster in VZV-seropositive immunocompromised adults. Further study is needed as data are limited on the safety and efficacy of recombinant varicella-zoster vaccine for primary varicella prevention in VZV-seronegative immunocompromised adults.

The Epidemiology of Chickenpox in England, 2016-2022: An Observational Study Using General Practitioner Consultations

Chickenpox is a common childhood disease caused by varicella-zoster virus (VZV). VZV vaccination is not part of the UK childhood immunisation programme, but its potential inclusion is regularly assessed. It is therefore important to understand the ongoing burden of VZV in the community to inform vaccine policy decisions. General practitioner (GP) chickenpox consultations were studied from 1 September 2016 to 9 December 2022. Over the study period, the mean weekly chickenpox consultation rate per 100,000 population in England was 3.4, with a regular peak occurring between weeks 13 and 15. Overall, rates decreased over time, from a mean weekly rate of 5.5 in 2017 to 4.2 in 2019. The highest mean weekly rates were among children aged 1-4 years. There was no typical epidemic peak during the COVID-19 pandemic, but in 2022, rates were proportionally higher among children aged < 1 year old compared to pre-pandemic years. Chickenpox GP consultation rates decreased in England, continuing a longer-term decline in the community. The COVID-19 pandemic impacted rates, likely caused by the introduction of non-pharmaceutical interventions to prevent SARS-CoV-2 transmission. The lasting impact of the interruption of typical disease transmission remains to be seen, but it is important to monitor the chickenpox burden to inform decisions on vaccine programmes.

Susceptibility of nursery teachers to measles, rubella, varicella and mumps in Japan

BACKGROUND

A guideline published in 2018 by the Ministry of Health, Labour and Welfare stipulated confirmation of the vaccine history of nursery staff members.

OBJECT

This study was conducted to elucidate nursery teachers' vaccine and infection histories for measles, mumps, rubella, and varicella through survey responses.

METHOD

After sending questionnaires through the mail to 5000 nursery teachers in November 2022, we received responses through December 2022. We measured the proportion of susceptibility in three ways. Additionally, we compared the proportions of susceptibility by disease by age class.

RESULTS

After receiving 1620 responses in all, the data of 1229 respondents under 50 years old were analyzed. Under the broad definition by which "no answer" was also regarded as unvaccinated or uinfected as well as "unknown," the proportions of susceptibility for measles, rubella, and varicella were higher: 22-23%. For mumps, the proportion was 42%. For varicella, they were 31% for respondents in their 30 s, and 14% for respondents in their 40 s. For mumps, the respective values were 58% and 26%.

DISCUSSION

Respondents assessed for this study were less susceptible and unknown in comparison with earlier studies investigating health care workers, school teachers, university students, and pregnant women.

CONCLUSION

The survey revealed that measles and rubella susceptibility was higher among respondents in their 30 s. However, it was higher for varicella and mumps among respondents in their 20 s.

Safety and Immunogenicity of Live Viral Vaccines in a Multicenter Cohort of Pediatric Transplant Recipients

Importance

Live vaccines (measles-mumps-rubella [MMR] and varicella-zoster virus [VZV]) have not been recommended after solid organ transplant due to concern for inciting vaccine strain infection in an immunocompromised host. However, the rates of measles, mumps, and varicella are rising nationally and internationally, leaving susceptible immunocompromised children at risk for life-threating conditions.

Objective

To determine the safety and immunogenicity of live vaccines in pediatric liver and kidney transplant recipients.

Design, Setting, and Participants

This cohort study included select pediatric liver and kidney transplant recipients who had not completed their primary MMR and VZV vaccine series and/or who displayed nonprotective serum antibody levels at enrollment between January 1, 2002, and February 28, 2023. Eligibility for live vaccine was determined by individual US pediatric solid organ transplant center protocols.

Exposures

Exposure was defined as receipt of a posttransplant live vaccine. Transplant recipients received 1 to 3 doses of MMR vaccine and/or 1 to 3 doses of VZV vaccine.

Main Outcome and Measure

Safety data were collected following each vaccination, and antibody levels were obtained at 0 to 3 months and 1 year following vaccination. Comparisons were performed using Mann-Whitney U test, and factors associated with development of postvaccination protective antibodies were explored using univariate analysis.

Results

The cohort included 281 children (270 [96%] liver, 9 [3%] kidney, 2 [1%] liver-kidney recipients) from 18 centers. The median time from transplant to enrollment was 6.3 years (IQR, 3.4-11.1 years). The median age at first posttransplant vaccine was 8.9 years (IQR, 4.7-13.8 years). A total of 202 of 275 (73%) children were receiving low-level monotherapy immunosuppression at the time of vaccination. The majority of children developed protective antibodies following vaccination (107 of 149 [72%] varicella, 130 of 152 [86%] measles, 100 of 120 [83%] mumps, and 124 of 125 [99%] rubella). One year post vaccination, the majority of children who initially mounted protective antibodies maintained this protection (34 of 44 [77%] varicella, 45 of 49 [92%] measles, 35 of 42 [83%] mumps, 51 of 54 [94%] rubella). Five children developed clinical varicella, all of which resolved within 1 week. There were no cases of measles or rubella and no episodes of graft rejection within 1 month of vaccination. There was no association between antibody response and immunosuppression level at the time of vaccination.

Conclusions and Relevance

The findings suggest that live vaccinations may be safe and immunogenic after solid organ transplant in select pediatric recipients and can offer protection against circulating measles, mumps, and varicella.

Seroprevalence of Measles, Mumps, Rubella, and Varicella-Zoster Virus and Seroresponse to the Vaccinations in Adult Solid Organ Transplant Candidates

BACKGROUND

Updating live vaccines such as measles, mumps, rubella, and varicella (MMRV) is an important step in preparing patients for solid organ transplant (SOT) to prevent morbidity from these preventable diseases. However, data for this approach are scarce. Thus, we aimed to describe the seroprevalence of MMRV and the efficacy of the vaccines in our transplant center.

METHODS

Pre-SOT candidates >18 y of age were retrospectively retrieved from SOT database in Memorial Hermann Hospital Texas Medical Center. MMRV serologies are routinely screened at the time of pretransplant evaluation. We divided patients into 2 groups: MMRV-positive group versus MMRV-negative group, patients with positive all MMRV serologies and with negative immunity to at least 1 dose of MMRV, respectively.

RESULTS

A total of 1213 patients were identified. Three hundred ninety-four patients (32.4%) did not have immunity to at least 1 dose of MMRV. Multivariate analysis was conducted. Older age (odds ratio [OR]: 1.04) and liver transplant candidates (OR: 1.71) were associated with seropositivity. Previous history of SOT (OR: 0.54) and pancreas/kidney transplant candidates (OR: 0.24) were associated with seronegativity. Among 394 MMRV seronegative patients, 60 patients received 1 dose of MMR vaccine and 14 patients received 1 dose of varicella-zoster virus vaccine without severe adverse events. A total of 35% (13/37) of patients who had follow-up serologies did not have a serological response.

CONCLUSIONS

A significant number of pre-SOT candidates were not immune to at least 1 dose of MMRV. This highlights the importance of MMRV screening and vaccinations pre-SOT. Postvaccination serological confirmation should be performed to evaluate the necessity for a second dose.

The epidemiology of varicella and effectiveness of varicella vaccine in Ganyu, China: a long-term community surveillance study

BACKGROUND

The real-world data of long-term protection under moderate vaccination coverage is limited. This study aimed to evaluate varicella epidemiology and the long-term effectiveness under moderate coverage levels in Ganyu District, Lianyungang City, Jiangsu Province.

METHODS

This was a population-based, retrospective birth cohort study based on the immunization information system (IIS) and the National Notifiable Disease Surveillance System (NNDSS) in Ganyu District. Varicella cases reported from 2009 to 2020 were included to describe the epidemiology of varicella, and eleven-year consecutive birth cohorts (2008-2018) were included to estimate the vaccine effectiveness (VE) of varicella by Cox regression analysis.

RESULTS

A total of 155,232 native children and 3,251 varicella cases were included. The vaccination coverage was moderate with 37.1%, correspondingly, the annual incidence of varicella infection increased 4.4-fold from 2009 to 2020. A shift of the varicella cases to older age groups was observed, with the peak proportion of cases shifting from 5-6 year-old to 7-8 year-old. The adjusted effectiveness of one dose of vaccine waned over time, and the adjusted VE decreased from 72.9% to 41.8% in the one-dose group.

CONCLUSIONS

The insufficient vaccination coverage (37.1%) may have contributed in part to the rising annual incidence of varicella infection, and a shift of varicella cases to older age groups occurred. The effectiveness of one dose of varicella vaccine was moderate and waned over time. It is urgent to increase varicella vaccine coverage to 80% to reduce the incidence of varicella and prevent any potential shift in the age at infection in China.

Explore the optimal timing for administering the second dose of the varicella vaccine in China

The prevalence of varicella in China has been increasing annually, with a relatively high incidence rate of breakthrough cases. Administering two doses of the varicella vaccine (Varv) proves to be the most effective measure. The objective of this study is to assess the immunogenicity of two doses of the Varv at varying intervals and explore the optimal timing for administering the second dose of the Varv. Utilizing a prospective cohort study design, the quantification of varicella immunoglobulin G (IgG) antibodies' geometric mean concentrations (GMC) is conducted through glycoprotein-based enzyme-linked immunosorbent assay (gpELISA). A total of 903 infants were included in the per-protocol population. After completing the first dose of the Varv, the GMC of antibody after 1 month (Group A) was 463.8 (447.6-480.1) mIU/mL. There was a statistically significant difference in GMC and seroconversion rates among the groups (B/C/D) that received the second dose of the Varv (p < 0.05). Multiple comparisons revealed that the group with a 3-year interval between the two vaccine doses had a higher GMC of 665.2 (622.6-707.8) mIU/mL compared to the group with a 1-year interval of 611.1 (577.1-645.3) mIU/mL and the group with a 5-year interval of 564.7 (540.1-589.4) mIU/mL. To effectively prevent and control the varicella epidemic in Jiangsu Province, two dose Varv vaccination is recommended, the optimal time point for the second dose Varv is 3 years after the first vaccination.

Catch-up vaccination and enhanced immunization against hepatitis B, hepatitis A, measles, mumps, rubella and varicella in children with idiopathic thrombocytopenic purpura

BACKGROUND

Limited data exist about the vaccination of children with idiopathic thrombocytopenic purpura (ITP) against vaccine preventable diseases. This study identified the vaccination status of children with ITP against hepatitis A, hepatitis B, measles, mumps, rubella and varicella, completed the immunization of children with inadequate immunization, re-evaluated post-vaccination antibody titers and identified probable vaccination-related complications.

PATIENTS AND METHODS

All of 46 children had chronic ITP were included. Seroconversion of hepatitis A, hepatitis B, varicella, measles, rubella and mumps vaccines was screened. All children with seronegative antibodies against vaccine preventable disease were given a vaccination appointment. Antibody levels were re-measured during a period ranging from 1 to 6 months. Potential complications were detected.

RESULTS

There were 46 children with a mean age of 12.25 years. All children had chronic ITP and received intravenous immunoglobulin at least once previously. Considering the vaccination status, 50% (23 children) had vaccinations appropriate for their age, 47.8% (22 children) did not know their vaccination status and 2.2% (1 patient) did not have vaccinations. Seven children (15.2%) were seropositive for all antibody types and the remaining 39 children were scheduled for vaccination. Post-vaccination antibody titers confirmed that all children became seropositive for each disease. There was no complication in any patient.

CONCLUSION

Immunization against hepatitis B, hepatitis A, measles, mumps, rubella and varicella is insufficient in a considerable number of children with ITP, Hepatitis B Virus (HBV) and Hepatitis A Virus (HAV) immunization being the most frequently inadequate. After immunization, adequate seroconversion levels were achievable without complications.

Australian Paediatric Surveillance Unit (APSU) Annual Surveillance Report 2022

For 30 years the Australian Paediatric Surveillance Unit (APSU) has conducted national surveillance of rare communicable diseases and rare complications of communicable diseases. In this report, we describe the results of thirteen such studies surveyed by the APSU in 2022, including reported case numbers and incidence estimates, demographics, clinical features, management and short-term outcomes. Conditions described are: acute flaccid paralysis (AFP); congenital cytomegalovirus (cCMV); neonatal and infant herpes simplex virus (HSV) infection; perinatal exposure to human immunodeficiency virus (HIV) and paediatric HIV infection; severe complications of influenza; juvenile-onset recurrent respiratory papillomatosis (JoRRP); congenital rubella infection/syndrome; congenital varicella syndrome (CVS) and neonatal varicella infection (NVI); and the new conditions dengue; Q fever; and severe acute hepatitis. In 2022, cases of severe complications of influenza were reported to the APSU for the first time since 2019. This likely reflects the easing of government-mandated restrictions imposed in 2020-2021 to curb the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the re-emergence of a range of infectious diseases. As previously, AFP surveillance by the APSU contributed to Australia achieving a minimum target incidence of one AFP case per 105 children aged less than 15 years. Cases of JoRRP and NVI were reported in 2022. This indicates potential gaps in human papillomavirus (HPV) and varicella vaccination coverage respectively, especially in high-risk groups such as young migrant and refugee women of childbearing age from countries without universal vaccination programs. Paediatric HIV case numbers resulting from mother-to-child-transmission (MTCT) of HIV remain low in Australia due to use of effective intervention strategies. However, there has been an increase in the number of imported cases of HIV in children (mainly perinatally-acquired) from countries with a high HIV prevalence. Without effective vaccines, there has been no decline in the incidence of congenital CMV and neonatal HSV, indicating the importance of early identification and management to reduce morbidity and mortality. The first cases of dengue, Q fever and severe acute hepatitis were received by APSU in 2022, including two cases of acute hepatitis in which aetiology has not been confirmed to date. The APSU has an important ongoing role in monitoring rare childhood infections.

The short and long-term impact of nonpharmaceutical interventions on the prevalence of varicella in Xi'an during the COVID-19 pandemic

Varicella is a highly prevalent infectious disease with a similar transmission pathway to coronavirus disease 2019 (COVID-19). In the context of the COVID-19 pandemic, anti-COVID-19 nonpharmaceutical interventions (NPIs) have been implemented to prevent the spread of the infection. This study aims to analyze varicella's epidemiological characteristics and further investigate the effect of anti-COVID-19 NPIs on varicella in Xi'an, northwestern China. Based on the varicella surveillance data, search engine indices, meteorological factors from 2011 to 2021 in Xi'an, and different levels of emergency response to COVID-19 during the pandemic, we applied Bayesian Structural Time Series models and interrupted time series analysis to predict the counterfactual incidence of varicella and quantify the impact of varying NPIs intensities on varicella. From 2011 to 2021, varicella incidence increased, especially in 2019, with a high incidence of 111.69/100 000. However, there was a sharp decrease of 43.18% in 2020 compared with 2019, and the peak of varicella incidence in 2020 was lower than in previous years from the 21st to the 25th week. In 2021, the seasonality of varicella incidence gradually returned to a seasonal pattern in 2011-2019. The results suggest that anti-COVID-19 NPIs effectively reduce the incidence of varicella, and the reduction has spatiotemporal heterogeneity.

Estimating the health economic impact of the universal varicella vaccination in Argentina from 2015 to 2019

Since the introduction of Universal Varicella Vaccination (UVV) in the Argentinean National Immunization Program in 2015, a significant decline in the incidence of varicella has been reported. This study aimed to estimate the economic impact of single-dose UVV in Argentina from 2015 to 2019. The economic impact was assessed based on the observed incidence of varicella in the post-UVV period and the number of cases avoided, obtained from a previously published study that used an Autoregressive Integrated Moving Average (ARIMA) model. The weighted average cost per case was calculated using local studies. The post-UVV cost reductions were calculated by multiplying the number of cases avoided from 2015 -2019 by the weighted average cost per case. Data were summarized yearly and by peak (September-November) periods for the target (1-4 years) and overall populations. We estimated avoided costs of United States dollars (USD) $65 million in the target population and $112 million in the overall population over 4 years following UVV introduction. We observed a trend toward greater reductions in costs over time, with substantial differences observed in peak periods. We estimated that the single-dose UVV program considerably reduced the economic burden of varicella in Argentina by avoiding direct and indirect costs associated with varicella management.

Impacts of routine varicella vaccination program and COVID-19 pandemic on varicella and herpes zoster incidence and health resource use among children in Japan

PURPOSE

To determine the epidemiological trends in pediatric varicella and herpes zoster incidence and changes in healthcare resource use from 2005 to 2022 using a nationally representative database in Japan.

MATERIALS AND METHODS

We conducted a retrospective observational study consisting of 3.5 million children with 177 million person-months during 2005-2022 using Japan Medical Data Center (JMDC) claims database in Japan. We investigated trends in incidence rates of varicella and herpes zoster and changes in healthcare resource use (e.g., antiviral use, office visits, and healthcare costs) over 18 years. Interrupted time-series analyses were used to investigate the impact of the routine varicella vaccination program in 2014 and infection prevention measures against COVID-19 on incidence rates of varicella and herpes zoster and related healthcare utilization.

RESULTS

After the introduction of the routine immunization program in 2014, we observed level changes in incidence rates (45.6 % reduction [95 %CI, 32.9-56.0] of varicella cases, antiviral use (40.9 % reduction [95 %CI, 25.1-53.3]), and relevant healthcare costs (48.7 % reduction [95 %CI, 38.2-57.3]). Furthermore, infection prevention measures against COVID-19 were associated with additional level changes in varicella rates (57.2 % reduction [95 %CI, 44.5-67.1]), antiviral use (65.7 % reduction [59.7-70.8]), and healthcare costs (49.1 % [95 %CI, 32.7-61.6]). In contrast, the changes in incidence and healthcare costs for herpes zoster were relatively small, which showed 9.4 % elevated level change with a decreasing trend and 8.7 % reduced level change with a decreasing trend after the vaccine program and the COVID-19 pandemic. The cumulative incidence of herpes zoster in children born after 2014 was lower than that before 2014.

CONCLUSIONS

Varicella incidence and healthcare resource use were largely affected by the routine immunization program and infection prevention measures against COVID-19, while these impacts on herpes zoster were relatively small. Our study indicates that immunization and infection prevention measures largely changed pediatric infectious disease practices.

Impact of implementing a free varicella vaccination policy on incidence in Wuxi City, China: an interrupted time series analysis

Varicella vaccination is optional and requires self-payment. On 1 December 2018, Wuxi City launched a free varicella vaccination program for children. This study aimed to evaluate the changes in varicella incidence before and after the implementation of the policy. The data were obtained from official information systems and statistical yearbooks. We divided the period into chargeable (January 2017 to November 2018) and free (December 2018 to December 2021) periods. Interrupt time series analysis was used to conduct a generalised least-squares regression analysis for the two periods. A total of 51,071 varicella cases were reported between January 2017 and December 2021. After the implementation of the policy, there was a statistically significant decrease in the incidence of varicella (β2 = -0.140, P = 0.017), and the slope of the incidence also decreased by 0.012 (P = 0.015). Following policy implementation, the incidence decreased in all age groups, with the largest decline observed among children aged 8-14 years (β2 = -1.109, P = 0.009), followed by children aged ≤7 years (β2 = -0.894, P = 0.013). Our study found a significant reduction in the incidence of varicella in the total population after the introduction of free varicella vaccination in Wuxi City.

Accounting for Adverse Events Following Immunization in Economic Evaluation: Systematic Review of Economic Evaluations of Pediatric Vaccines Against Pneumococcus, Rotavirus, Human Papillomavirus, Meningococcus and Measles-Mumps-Rubella-Varicella

OBJECTIVES

Economic evaluations of vaccines should accurately represent all relevant economic and health consequences of vaccination, including losses due to adverse events following immunization (AEFI). We investigated to what extent economic evaluations of pediatric vaccines account for AEFI, which methods are used to do so and whether inclusion of AEFI is associated with study characteristics and the vaccine's safety profile.

METHODS

A systematic literature search (MEDLINE, EMBASE, Cochrane Systematic Reviews and Trials, Database of the Centre for Reviews and Dissemination of the University of York, EconPapers, Paediatric Economic Database Evaluation, Tufts New England Cost-Effectiveness Analysis Registry, Tufts New England Global Health CEA, International Network of Agencies for Health Technology Assessment Database) was performed for economic evaluations published between 2014 and 29 April 2021 (date of search) pertaining to the five groups of pediatric vaccines licensed in Europe and the United States since 1998: the human papillomavirus (HPV) vaccines, the meningococcal vaccines (MCV), the measles-mumps-rubella-varicella (MMRV) combination vaccines, the pneumococcal conjugate vaccines (PCV) and the rotavirus vaccines (RV). Rates of accounting for AEFI were calculated, stratified by study characteristics (e.g., region, publication year, journal impact factor, level of industry involvement) and triangulated with the vaccine's safety profile (Advisory Committee on Immunization Practices [ACIP] recommendations and information on safety-related product label changes). The studies accounting for AEFI were analyzed in terms of the methods used to account for both cost and effect implications of AEFI.

RESULTS

We identified 112 economic evaluations, of which 28 (25%) accounted for AEFI. This proportion was significantly higher for MMRV (80%, four out of five evaluations), MCV (61%, 11 out of 18 evaluations) and RV (60%, nine out of 15 evaluations) compared to HPV (6%, three out of 53 evaluations) and PCV (5%, one out of 21 evaluations). No other study characteristics were associated with a study's likelihood of accounting for AEFI. Vaccines for which AEFI were more frequently accounted for also had a higher frequency of label changes and a higher level of attention to AEFI in ACIP recommendations. Nine studies accounted for both the cost and health implications of AEFI, 18 studies considered only costs and one only health outcomes. While the cost impact was usually estimated based on routine billing data, the adverse health impact of AEFI was usually estimated based on assumptions.

DISCUSSION

Although (mild) AEFI were demonstrated for all five studied vaccines, only a quarter of reviewed studies accounted for these, mostly in an incomplete and inaccurate manner. We provide guidance on which methods to use to better quantify the impact of AEFI on both costs and health outcomes. Policymakers should be aware that the impact of AEFI on cost-effectiveness is likely to be underestimated in the majority of economic evaluations.

Reduced antiviral seropositivity among patients with inflammatory bowel disease treated with immunosuppressive agents

BACKGROUND

Although live-attenuated vaccines are contraindicated under immunosuppression, the immune status of patients with inflammatory bowel disease (IBD) has not been fully assessed prior to immunosuppressive therapy.

AIMS

To investigate antiviral serostatus against viruses requiring live vaccines for prevention in IBD patients undergoing immunosuppressive therapy.

METHODS

This multicenter study included IBD patients who were aged <40 years and were treated with thiopurine monotherapy, molecular-targeted monotherapy, or combination therapy. Gender- and age-matched healthy subjects (HS) living in the same areas were included as control group. Antibody titers against measles, rubella, mumps, and varicella were measured by enzyme-linked immunosorbent assays.

RESULTS

A total of 437 IBD patients (163 ulcerative colitis [UC] and 274 Crohn's disease [CD]) and 225 HS were included in the final analysis. Compared with HS, IBD patients had lower seropositivity rates for measles (IBD vs. HS = 83.91% vs. 85.33%), rubella (77.55% vs. 84.89%), mumps (37.50% vs. 37.78%), and varicella (91.26% vs. 96.44%). Gender- and age-adjusted seropositivity rates were lower in UC patients than in both CD patients and HS for measles (UC, CD, and HS = 81.60%, 85.29%, and 85.33%), rubella (76.40%, 78.23%, and 84.89%), mumps (27.16%, 43.70%, and 37.78%), and varicella (90.80%, 91.54%, and 96.44%); the difference was significant for all viruses except measles. Divided by the degree of immunosuppression, there were no significant differences in seropositivity rates among IBD patients.

CONCLUSIONS

IBD patients, especially those with UC, exhibit reduced seropositivity rates and may benefit from screening prior to the initiation of immunosuppressive therapy.

Parental acceptance of and preferences for administration of routine varicella vaccination in the UK: A study to inform policy

OBJECTIVES

To explore acceptability of and preferences for the introduction of varicella vaccination to the UK childhood immunisation schedule.

DESIGN

We conducted an online cross-sectional survey exploring parental attitudes towards vaccines in general, and varicella vaccine specifically, and their preferences for how the vaccine should be administered.

PARTICIPANTS

596 parents (76.3% female, 23.3% male, 0.4% other; mean age 33.4 years) whose youngest child was aged 0-5 years.

MAIN OUTCOME MEASURES

Willingness to accept the vaccine for their child and preferences for how the vaccine should be administered (in combination with the MMR vaccine [MMRV], on the same day as the MMR vaccine but as a separate injection [MMR + V], on a separate additional visit).

RESULTS

74.0% of parents (95% CI 70.2% to 77.5%) were extremely/somewhat likely to accept a varicella vaccine for their child if one became available, 18.3% (95% CI 15.3% to 21.8%) were extremely/somewhat unlikely to accept it and 7.7% (95% CI 5.7% to 10.2%) were neither likely nor unlikely. Reasons provided by parents likely to accept the vaccine included protection from complications of chickenpox, trust in the vaccine/healthcare professionals, and wanting their child to avoid their personal experience of chickenpox. Reasons provided by parents who were unlikely included chickenpox not being a serious illness, concern about side effects, and believing it is preferable to catch chickenpox as a child rather than as an adult. A combined MMRV vaccination or additional visit to the surgery were preferred over an additional injection at the same visit.

CONCLUSIONS

Most parents would accept a varicella vaccination. These findings highlight parents' preferences for varicella vaccine administration, information needed to inform vaccine policy and practice and development of a communication strategy.

Anti-varicella-zoster virus antibody titers and seroprotection status from before the first dose of varicella vaccination to before entering elementary school in one region in Japan

OBJECTIVE

We aimed to examine changes in anti-varicella-zoster virus (VZV) antibody titers and seroprotection status from before the first dose of vaccination to before 7 years old entering elementary school in children who received the routine two-dose varicella vaccination.

METHODS

Participants were 37 healthy children who received the routine two-dose varicella vaccination at our hospital. A total of five serum samples per child were collected immediately before and 4-6 weeks after each dose of the vaccination and in the year before entry to elementary school. We measured anti-VZV antibody titers by immune adherence hemagglutination (IAHA) method and glycoprotein-based enzyme-linked immunosorbent assay (gpELISA). A positive antibody titer and the seroprotection level were set as ≥2-fold and ≥16-fold, respectively, for IAHA antibody and as ≥50 units and ≥105 units, respectively, for gpELISA-IgG antibody.

RESULTS

The rates of IAHA antibody positivity in the five samples (in order of collection) were 0%, 65%, 38%, 100%, and 59%, and the rates of seroprotection were 0%, 43%, 8%, 100%, and 43%. The rates of gpELISA-IgG antibody positivity were 8%, 81%, 89%, 100%, and 100%, and the rates of seroprotection were 5%, 54%, 70%, 100%, and 89%. The mean IAHA antibody titer and mean gpELISA-IgG antibody titer before entering elementary school were both lower than the respective titers obtained after the second vaccination (both p < 0.01).

CONCLUSIONS

Routine two-dose varicella vaccination leads to good antibody production, but titers of acquired antibodies decrease before children enter elementary school.

Disseminated varicella zoster virus infection following live attenuated herpes zoster vaccine: descriptive analysis of reports to Australia's spontaneous vaccine pharmacovigilance system, 2016-2020

OBJECTIVES

To examine the reported incidence and features of disseminated varicella zoster virus (VZV) infection following live attenuated herpes zoster vaccine live (ZVL: Zostavax, Merck) in immunocompromised people in Australia.

DESIGN AND SETTING

ZVL was funded in 2016 in Australia for people aged 70 years, with a catch-up programme for those 71-79 years. From 2016 to 2020, three deaths due to disseminated vaccine-strain VZV infection occurred following inadvertent ZVL administration in individuals with varying levels of immunocompromise. This descriptive study examined 4 years of national surveillance data reported to the Therapeutic Goods Administration's Adverse Event Monitoring System (AEMS). Denominator data for rates were from doses recorded in the Australian Immunisation Register.

PARTICIPANTS

Individuals vaccinated between 1 November 2016 and 31 December 2020 who experienced adverse event(s) following immunisation (AEFI) after ZVL recorded in the AEMS.

PRIMARY AND SECONDARY OUTCOME MEASURES

Rates and outcomes of confirmed (Oka strain positive) or probable disseminated VZV infection, and inadvertent administration of ZVL in immunocompromised individuals.

RESULTS

854 AEFI were reported from 1 089 966 doses of ZVL administered (78.4 per 100 000 doses). Of those, 14 were classified as confirmed (n=6, 0.55 per 100 000) or probable (n=8) disseminated VZV infection. The confirmed cases were all hospitalised, and most (5/6) were immunocompromised; three cases died. Thirty-seven individuals were reported as vaccinated despite a contraindication due to immunocompromise (3.4 per 100 000), with 12/37 (32%) hospitalised.

CONCLUSIONS

Disseminated VZV is potentially life-threatening and occurs mostly in those with severe immunocompromise. Inadvertent administration of ZVL to immunocompromised individuals has occurred despite initial provider guidance and education. Multiple additional strategies to assist providers to identify contraindications have been implemented to prevent adverse outcomes.

Combined measles-mumps-rubella-varicella vaccine and febrile convulsions: the risk considered in the broad context

INTRODUCTION

Studies on quadrivalent measles, mumps, rubella, and varicella (MMRV) vaccines have indicated a twofold increased relative risk of febrile convulsion (FC) after the first dose compared to MMR and V administered at the same medical visit (MMR+V).

AREAS COVERED

This narrative review contextualizes FC occurrence after the first MMRV vaccine dose from a clinical perspective and outlines approaches to attenuate FC occurrence post-vaccination.

EXPERT OPINION

While the relative FC risk increases after the first dose of MMRV compared to MMR+V vaccine in measles-naïve infants, the attributable risk is low versus the overall FC risk in the pediatric population triggered by other causes, like natural exposure to pathogens or routine vaccination. No increased risk of FC has been reported after MMRV co-administration with other routine vaccines compared to MMRV alone. Based on our findings and considering the MMRV vaccination benefits (fewer injections, higher coverage, better vaccination compliance), the overall benefit-risk profile of MMRV vaccine is considered to remain positive. Potential occurrence of FC in predisposed children (e.g. with personal/family history of FC) may be attenuated if they receive MMR+V instead of MMRV as the first dose. It is also important to monitor vaccinees for fever during the first 2 weeks post-vaccination.