Epidemiology Of Varicella Research Articles

Preliminary investigation and analysis of nucleotide site variability of nine glycoproteins on varicella-zoster virus envelope, Jilin Province, China, 2010-March 2024

Varicella is endemic worldwide. In China, varicella has not yet been included in the list of legal infectious diseases, nor has a unified national surveillance program been established. And the live attenuated varicella vaccine has not been included in routine immunization. In this study, we analyzed for the first time the varicella epidemiology in Jilin Province in the past 20 years, and the nucleotide site, amino acid site and N-glycosylation site variation of glycoprotein in varicella-zoster virus (VZV) surface 9 in the past 15 years. The results showed that the reported incidence of varicella in Jilin Province in the last 20 years was fluctuating above and below 20/100,000, especially after the epidemic of the COVID-19, and fatal cases appeared in individual years. The genotypic branching of VZV was monitored as Clade 2 in the last 15 years. 9 glycogen nucleotide sites of VZV had different degrees of variability, and the variability had specificity. Therefore, it gives us the idea that in order to reduce the incidence of varicella and herpes zoster, a provincial or even national surveillance program should be introduced as early as possible, and the dynamic monitoring of the variability of the nucleotide sites of VZV should be strengthened at the same time as the vaccine immunization strategy is introduced.

Impact of the COVID-19 pandemic on the epidemiology of hand-foot-and-mouth disease and varicella in a general hospital in Guangzhou, China

We retrospectively reviewed the medical records of patients with hand-foot-and-mouth disease (HFMD) and varicella treated in a general hospital in Guangzhou, China between 2017 and 2023 to evaluate the effect of the coronavirus disease 2019 (COVID-19) on the epidemiology of HFMD and varicella in Guangzhou. The epidemiological characteristics of HFMD and varicella before (2017–2019), during (2020–2022), and after (2023) the pandemic were compared. In total, 1731 cases of HFMD and 1043 cases of varicella were reported before the COVID-19 pandemic (2017–2019), with average reporting rates of 0.08% and 0.05%, respectively. During the COVID-19 pandemic (2020–2022), the number of reported cases of HFMD and varicella decreased to 571 and 389, respectively, with average reporting rates of 0.03% and 0.02%, respectively, which were significantly different from those in the pre-pandemic period (P < 0.001). In the post-pandemic period (2023), the reporting rate of HFMD was 0.07%, showing a marked increase compared with that in 2022 (P < 0.001). However, the difference in the reporting rate of varicella in 2023 did not differ significantly from that in 2022 (P =0.204). These results suggest that non-pharmaceutical interventions implemented during the COVID-19 pandemic might be helpful in preventing the spread of HFMD and varicella.

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

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. 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. 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. 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. 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.

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

BackgroundThe 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.MethodsThis 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.ResultsA 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.ConclusionsThe 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.

Delineating the Seasonality of Varicella and Its Association With Climate in the Tropical Country of Colombia.

Varicella causes a major health burden in many low- to middle-income countries located in tropical regions. Because of the lack of surveillance data, however, the epidemiology of varicella in these regions remains uncharacterized. In this study, based on an extensive dataset of weekly varicella incidence in children ≤10 during 2011-2014 in 25 municipalities, we aimed to delineate the seasonality of varicella across the diverse tropical climates of Colombia. We used generalized additive models to estimate varicella seasonality, and we used clustering and matrix correlation methods to assess its correlation with climate. Furthermore, we developed a mathematical model to examine whether including the effect of climate on varicella transmission could reproduce the observed spatiotemporal patterns. Varicella seasonality was markedly bimodal, with latitudinal changes in the peaks' timing and amplitude. This spatial gradient strongly correlated with specific humidity (Mantel statistic = 0.412, P = .001) but not temperature (Mantel statistic = 0.077, P = .225). The mathematical model reproduced the observed patterns not only in Colombia but also México, and it predicted a latitudinal gradient in Central America. These results demonstrate large variability in varicella seasonality across Colombia and suggest that spatiotemporal humidity fluctuations can explain the calendar of varicella epidemics in Colombia, México, and potentially in Central America.

Seasonal and epidemiological profile of chickenpox cases in Kazakhstan

<b>Background</b><b>: </b>According to the National infectious disease monitoring report, there is a fluctuating pattern of incidence of chickenpox in the country, but there are no studies reporting the epidemiological situation in Kazakhstan. There is a discernable association of varicella epidemiology with climate, particularly temperature dependency. We aimed to analyze the incidence and seasonality of chickenpox in the absence of universal varicella vaccination in Kazakhstan.<br /> <b>M</b><b>aterial and m</b><b>ethods</b><b>: </b>A retrospective analysis of the long-term dynamics of chickenpox was carried out, and data he state report "Sanitary and epidemiological situation in the Republic of Kazakhstan for 2020" and data from the Unified Payment System (UPS) from 2014 to 2020 were used.<br /> of registered patients between 2010 and 2020 were retrieved from the National infectious disease monitoring report and the Unified Payment System (UPS) database from 2014 to 2020, which is part of the Unified National Electronic Health System (UNEHS).<br /> <b>Results</b><b>: </b>The highest incidence rate for the studied period was registered in 2014 – 363.96 and the lowest was in 2020 – 95.8 per 100,000 population. Overall, 17,520 cases of chickenpox were recorded with an incidence rate of 95.8 per 100,000 population in the country in 2020 (against 41,841 cases, with an indicator of 228.9 in 2019). The highest proportion of cases is observed among children from 4 to 6 years old (29%), children from 1 to 3 years old  (24%)  and  from 7 to 9 years old (15%) . Similar to previous years, there was an autumn-winter spreadingdistribution of morbidity, with the highest registration of morbidity in January.<br /> <b>Conclusion</b><b>: </b>The findings of this study can aid in the prediction of epidemics and the preparation for the impact of climate change on the disease mentioned in epidemiology by implementing preventive puBased on our study, the highest incidence rate of chickenpox in Kazakhstan was registered in 2014 (363.96 per 100,000 population) and morbidity was distributed in the autumn-winter season. These findings might aid in forecasting future outbreaks of infection based on the influence of climate change on chickenpox, and help in making a decision about the implementation of varicella preventive and control initiatives in the country.

Epidemiological Characteristics of Varicella Outbreaks - China, 2006-2022.

Varicella outbreaks significantly disrupt schools and other child-centered institutions. This study aimed to identify patterns and epidemiological features of varicella outbreaks in China from 2006 to 2022. Data were extracted from outbreak reports submitted to the Public Health Emergency Reporting Management Information System within the specified timeframe. Analytical methods included Spearman correlation tests and the Mann-Kendall trend tests, conducted using R software to analyze and summarize reported data. Additionally, statistical analyses of trends and epidemiological characteristics were performed using SPSS software. Between 2006 and 2022, a total of 11,990 varicella outbreaks were reported in China, resulting in 354,082 cases. The attack rates showed a decreasing trend over the years (Z=-4.49, P<0.05). These outbreaks occurred in two peaks annually. The eastern region accounted for the highest number of outbreaks (31.53%), followed by the southwestern (24.22%) and southern (17.93%) regions. Varicella outbreaks were most common in elementary schools. Most of the outbreaks (60.43%) were classified as Grade IV (general) severity, with 86.41% of the outbreaks having 10-49 cases. The median and inter-quartile ranges (IQR) of the duration of outbreaks, response time, and case counts were 21 (10, 39) days, 4 (0, 12) days, and 23 (16, 35) cases, respectively. These variables showed a positive correlation (P<0.001). Varicella outbreaks exhibited fluctuating trends, initially decreasing until 2012, followed by an increase, reaching the highest peak in 2018-2019. Continual monitoring of varicella epidemiology is necessary to assess the burden of the disease and formulate evidence-based strategies and policies for its prevention and control.

Effect of Routine Varicella Immunization on the Epidemiology and Immunogenicity of Varicella and Shingles.

Varicella-zoster virus (VZV) causes varicella as a primary infection and remains latent in the ganglia until it becomes reactivated to cause herpes zoster. Individuals with varicella develop adaptive humoral and cell-mediated immunity. Compromised cell-mediated immunity is thought to contribute to the development of herpes zoster. Recent evidence suggests that changes in the epidemiology of varicella have affected the epidemiology of herpes zoster. The incidence of herpes zoster is higher in older adults; thus, the herpes zoster vaccine is recommended for older adults. However, the incidence of herpes zoster is expected to rise among younger individuals; hence, vaccination with the varicella vaccine should also be considered in younger adults. In order to determine the need for vaccination in different populations, it is important to establish methods to accurately assess the activity of cell-mediated immunity and humoral immunity.

Modelling varicella vaccination – What does a lack of surge in herpes zoster incidence tell us about exogenous boosting?

BackgroundFor decades, assessments of the impact of universal varicella vaccination on the epidemiology of varicella and herpes zoster (HZ) have been made using mathematical modelling. Decreased virus circulation and the resulting diminished exogenous boosting have been predicted to lead to a surge in HZ incidence. Lately, the exogenous boosting hypothesis has been challenged due to a lack of an extensive surge in HZ incidence in countries with, by now long-standing universal varicella vaccination. MethodsIn a deterministic compartmental transmission model of varicella zoster virus disease, we model various levels and duration of protection from boosting to explore the impact of successful childhood varicella vaccination on HZ incidence. ResultsConsidering total HZ incidence, lifelong and strong protection from boosting give a stable incidence of HZ for about 60 years followed by a decline, whereas lifelong intermediate protection leads to a decline. So does weak protection of intermediate duration. Full and short protection, lead to a small surge, while full and intermediate protection lead to the largest HZ surge. HZ incidence by age group show that total incidence is the result of opposing increasing and decreasing trends in the various age groups over time. ConclusionsThe absence of an extensive surge in HZ incidence after varicella vaccination can, especially during the first 20–30 years, occur in either strong, intermediate or weak boosting scenarios. The impact seems to depend on an interplay of the protective level and duration of the protection in determining the basic reactivation rate and the proportion of the population that is susceptible at the start of vaccination. However, the picture depends on whether the entire population or specific age groups are observed.

VARICELLA PNEUMONIA: ADULT COMPLICATIONS OF A CHILDHOOD DISEASE

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: Varicella has drastically declined since 1995 when vaccination was introduced in the United States. Children accounted for the majority of cases but adults were more likely to develop complicated disease. Pneumonia has been shown to be disproportionally present in adults and we present two such cases of varicella pneumonia. CASE PRESENTATION: A 25-year-old male who recently immigrated from Guatemala presented with a rash that began on his face and spread down to his trunk. He noted a dry cough, shortness of breath, fevers, sore throat and lethargy. He was febrile and tachycardic with a widespread vesicular rash, and lesions in varying stages of healing. His CT noted nodular opacities in the mid and upper lungs with a prominent 13mm nodule in the right apex. He was found to have a bandemia and a positive varicella IgM. He was treated with a course of IV acyclovir and was discharged with a plan to obtain repeat imaging to follow up the nodules.A 38-year-old man with polysubstance use and asthma presented with shortness of breath and a rash that started on his scalp and descended to his chest and back associated with a burning sensation. He had a cough without sputum production. He was afebrile on exam and had a diffuse rash over the face and trunk consistent with chickenpox. The initial CXR showed bilateral infiltrates and CT chest noted numerous pulmonary nodules throughout both lung fields. Atypical infection was the initial concern but a broad workup was otherwise unrevealing other than a positive zoster IgM. He was treated with valacyclovir and discharged with a plan for repeat imaging. DISCUSSION: With varicella vaccination efforts, incidence, hospitalizations and deaths have all decreased since 19954. Adults are more prone to pneumonia, which has been reported as the leading cause of complicated disease in adults, up to 1/400 patients, but total incidence is likely difficult to assess as many patients with mild symptoms may not have radiographs. Smoking, pregnancy, immunosuppression and male sex are considered risk factors for pneumonia. On xray diffuse bilateral infiltrates and nodularity can be seen, while CTs can show nodular opacities, patchy ground glass opacities, or even a miliary pattern that generally resolve as the rash does, but can persist as calcified nodules. CONCLUSIONS: These cases highlight the need for providers to be able to recognize vaccine preventable diseases, especially in patients not born in the United States. With the current climate of vaccine hesitancy, it is likely health care providers will experience the ill effects of adult varicella in the future as unvaccinated children become adults susceptible to more invasive disease. REFERENCE #1: Alanezi, M. (2007). Varicella pneumonia in adults: 13 Years' experience with review of literature. Annals of Thoracic Medicine, 2(4), 163–165. https://doi.org/10.4103/1817-1737.36551 REFERENCE #2: Franquet, T. (2011). Imaging of pulmonary viral pneumonia. Radiology, 260(1), 18–39. https://doi.org/10.1148/radiol.11092149 REFERENCE #3: Guris, D., Jumaan, A. O., Mascola, L., Watson, B. M., Zhang, J. X., Chaves, S. S., Gargiullo, P., Perella, D., Civen, R., & Seward, J. F. (2008). Changing varicella epidemiology in active surveillance sites - United States, 1995-2005. Journal of Infectious Diseases, 197(SUPPL. 2), 71–75. https://doi.org/10.1086/522156 DISCLOSURES: No relevant relationships by Jacqueline Burnell, source=Web Response No relevant relationships by Rohit Gupta, source=Web Response No relevant relationships by Truong-An Ho, source=Web Response

CHICKENPOX VACCINE : NEED OF THE HOUR IN DIFFERENT REGIONS OF JHARKHAND

Varicella (chickenpox) is caused by varicella zoster virus (VZV). Epidemiological prole of chickenpox varies considerably across different parts of world. In Jharkhand, chickenpox remains an important public health issue and outbreaks are not uncommon, since vaccination is not universal. Aim: To study different demographic variables in the outbreaks of chicken pox infection in Jharkhand from January 2017 to December 2020. Methods: Surveillance data were collected monthly, as a part of the Integrated Disease Surveillance program, India. The clinical denition of cases and outbreak were used for the surveillance rates and outbreaks. Chickenpox outbreaks were analyzed in different districts of Jharkhand for a period of 4 years (2017 - 2020) and trends were analyzed according to age, sex, residency and seasonality. Results: Three, fteen, twenty four and seven Chickenpox outbreaks occurred in 2017, 2018, 2019 and 2020 respectively which caused fteen, seventy six, one hundred and thirty seven and fty two cases respectively altogether in Jharkhand . There was minor difference in occurrence among genders. A seasonal pattern was also observed. The age group of patients who were maximum affected were of 5-9 years followed by 10-14 years. Conclusion: A programme of varicella vaccination can potentially change the epidemiology of varicella and limit its burden in childhood as well as its social and nancial cost

The impact of two-dose varicella vaccination on varicella and herpes zoster incidence in South Korea using a mathematical model with changing population demographics

BackgroundIn South Korea, one-dose varicella vaccination was introduced to the National Immunization Program in 2005, but varicella outbreaks have continued to occur. Therefore, a two-dose vaccination strategy is considered. MethodsWe developed an age-structured deterministic compartment model using Korean population projection data. The impact of adding a second dose of varicella vaccine on varicella and herpes zoster (HZ) epidemiology was assessed under four different vaccine effectiveness (VE) scenarios (base, moderate, lowest, highest) and the optimal timing of the second vaccine dose (18 months, 4, 5, or 6 years of age) was examined over the period 2020–2065. ResultsA two-dose vaccination schedule reduced the cumulative varicella incidence by > 90% compared to no vaccination, regardless of the VE. The additional reduction attributable to a second dose compared to a single dose was greatest (82%) with the lowest VE scenario. A second dose at 6 years of age reduced the varicella incidence at a population level, whereas a second dose at 18 months of age reduced the varicella incidence primarily in the target birth cohorts. Routine vaccination at the age of 18 months with a catch-up vaccination of 6-year-olds was the optimal strategy for birth cohort and population-level control. HZ incidence continued to increase under no vaccination scenario, which represents the effect of aging population. Under a two-dose scenario, the additional increase in HZ incidence attributable to the reduced exogenous boosting was small relative to a one-dose scenario and a further reduction in HZ cases was observed. ConclusionA two-dose varicella vaccination schedule would significantly reduce varicella and HZ incidence in the long term. A second dose at the age of 18 months with a catch-up vaccination of 6-year-olds would be optimal for controlling varicella in South Korea.

Seasonal variation and role of meteorological conditions in reported chicken pox cases in a residential hostel of Ramgarh

Background: Chicken pox is an acute, common, and highly contagious disease caused by the varicella zoster virus (VZV). Chicken pox is predominantly a childhood disease characterized by pruritic vesicular exanthema with systemic symptoms such as fever, loss of appetite, and malaise. Primary infection tends to occur at a younger age and is usually benign in immunocompetent children but can be life-threatening in adults and immunocompromised individuals, with an attack rate approaching &gt;85% after exposure. This study attempts to evaluate the trend of chickenpox cases in a residential hostel in Ramgarh.Methods: This was a record based descriptive study done using reported Chicken Pox cases in the OPDs during the period from January 2015 to December 2018. Monthly average for meteorological data (Min and Max temperature, Precipitation and Humidity) for Ramgarh was recorded for the study period. Seasonality and trend was identified for chicken pox cases during this period by plotting the monthly number of clinically diagnosed cases over time period to identify any repeated pattern. Poisson’s distribution was used to estimate association between meteorological variables and incidence of chickenpox cases.Results: Analysis revealed strong correlations (r=0.7553, p&lt;0.0001) between humidity and precipitation. There was a significant correlation between Incidence of varicella and meteorological factors under study (all p&lt;0.05).Conclusions: The findings of this study will aid in forecasting epidemics and in preparing for the impact of climate change on the varicella epidemiology through the implementation of public health preventive measures such as promoting good hygiene practices, temporary closure of educational institutions, active vaccination and campaigns that include press releases and media events to encourage preventive activities.

INTERNET BASED DATA AS A POWERFUL TOOL FOR TRACKING INFECTIOUS DISEASE DYNAMICS

Purpose: Digital epidemiology (using Internet data as an epidemiological tool) is one of the most concurrent and novel approaches in the field of infectious disease tracking. We aimed to see if the disease-related information seeking via one of the most popular search engine (Google) correlates with the real varicella epidemiology in Bulgaria. Material/Methods: We compared the relative search index obtained by Google Trends with a keyword ‘varicella’ and the real incidence data for 2016-2018 in Bulgaria. Correlation analysis and t-test were used to see for association and difference in the means. Additionally, we summarized what type of information people find when searching for ‘varicella’. Results: Dynamics of Google Trends with search term ‘varicella’ followed almost exactly the real dynamics of reported varicella cases in Bulgaria (Pearson’s correlation coefficient of 0.85). The seasonality and the regional spread of varicella infection were also confirmed by the digital epidemiology (Pearson’s correlation coefficient between the search index and the monthly cases was 0.93 and between the search index and the individual district incidence was 0.35). The majority of the information found by people during the seasonal varicella outbreaks was scientifically relevant and correct. Conclusions: Digital data received by non-epidemiological methods could be successfully used to study varicella dynamics, as high correlation exists between the data collected via the traditional methods and via the new, digital methodology.

One single-center cross-sectional investigation on varicella antibody level of all age groups in Chinese people

ABSTRACT Varicella outbreaks were mainly reported in developed regions with high vaccine coverage, but not in undeveloped areas. It is still not clear that whether the published data of varicella epidemiology could reflect the reality in China or not. In 2019, 657 subjects from People’s Hospital of Chongqing Youyang County were included. Anti-varicella-zoster virus (VZV) IgG antibodies were determined by ELISA. The anti-VZV IgG levels were categorized as positive when values were ≥100 mIU/mL. Our results showed that the rates of anti-VZV IgG seropositivity (χ2 = 328.957, P < .0001) and geometric mean titers (P < .0001) were significantly influenced by age. The seropositivity declined dramatically from 84.5% in subjects ≤3 m of age, to 7.9% in subjects of >3 m-1 y (P < .0001). Then, the positivity rate increased slowly as age to 26.7% in >1-<3 y (P = .0006), and 34.5% in 3-<7 y (P = .4294). A steady rise (45.6%) in positivity was observed in subjects aged 7-<18 y. After then, the positivity began to increase robustly. A total of 87.8% of adults aged 18-<40 y had acquired VZV-specific immunity (P < .0001). The highest positivity rate was found in 40-<60 y (98.3%) and ≥60 y (98.2%) group. In conclusion, most subjects of >3 m-<7 y age were susceptible to VZV. The proportion of subjects with natural infection-induced immunity increased with age. Nearly all subjects over 40 ages had positive anti-VZV IgG antibodies, which proved that they were infected by this virus in the past. These results suggested that VarV should be included in the national immunization program in China.

Epidemiology of varicella among immigrants and non-immigrants in Quebec, Canada, before and after the introduction of childhood varicella vaccination: a retrospective cohort study

Many immigrants are susceptible to varicella on arrival to Canada because of different transmission dynamics in their countries of origin and scarcity of vaccination. Universal childhood vaccination programmes decrease varicella incidence rates through herd immunity, but the accumulating number of susceptible adult immigrants could remain at risk for severe varicella. Our aim was to describe the epidemiology of varicella among immigrants and non-immigrants before and after childhood varicella vaccination. We did a population-based, retrospective cohort study of all varicella cases in Quebec, Canada, diagnosed between 1996 and 2014 in administrative health databases linked to immigration data. Cases of varicella met diagnostic codes in the International Classification of Diseases, Ninth and Tenth Revision Canadian modifications. Cases with a co-occurring zoster diagnostic code and immigrants from Australia, New Zealand, the USA, and western European countries were excluded. Vaccination periods included pre-vaccination (1996-98), private vaccination (1999-2005), and public vaccination (2006-14). Incidence rate and comparative rate ratios were estimated using census data. A total of 231 339 varicella cases diagnosed between Jan 1, 1996, and Dec 31, 2014, were linked to 1 115 696 immigrants who arrived between Jan 1, 1980, and Dec 31, 2014. 1444 herpes zoster cases and 1276 immigrants from Australia, western Europe, New Zealand, and the USA were excluded. Among 228 619 varicella cases, 13 315 (5·8%) occurred in immigrants. In pre-vaccination versus public vaccination periods, varicella incidence declined in immigrants by 87% (95% CI 86·6-87·9; 324·3 cases per 100 000 person-years to 40·9 cases per 100 000 person-years) and in non-immigrants by 93% (92·4-92·7; 484 cases per 100 000 person-years to 36 cases per 100 000 person-years). Mean age at diagnosis increased in both groups (15·1 vs 19·4 years in immigrants and 8·4 vs 12·0 years in non-immigrants). In the public vaccination period, immigrants younger than 50 years had higher varicella rates than non-immigrants, with relative risk ranging from 1·53 (95% CI 1·37-1·72) to 4·64 (3·90-5·53) with the highest risk in adolescents and young adults, and people from Latin America and the Caribbean (age-specific incidence rate ratio [aIRR]I-NI pre-vaccination 2·19 and post-vaccination aIRRI-NI6·07) and south Asia (aIRRI-NI pre-vaccination 3·41 and aIRRI-NI post-vaccination 4·46) and in childbearing women (15-40 years; IRRI-NI 2·48). Immigrant adolescents, young adults, and women of childbearing age had higher age-standardised rates of varicella than non-immigrants, with increasing disparities following vaccine introduction. Immigrants younger than 50 years of age would benefit from targeted vaccination upon arrival to host countries. The Canadian Institutes of Health Research and The Department of Medicine, Jewish General Hospital, Montreal, QC, Canada.

Seroprevalence survey for Varicella among healthcare workers and medical students in Italy

ABSTRACT Varicella is a potentially serious infectious disease caused by Varicella-Zoster Virus (VZV). In Italy childhood varicella vaccine have gradually introduced into national immunization program since 2003 and from 2017 a two-doses schedule has been stated nationally for all newborns and has become compulsory for school attendance. VZV exposures among healthcare workers (HCWs) and patients can be really dangerous and expensive. According to Centers of Disease Control and Italian national immunization plan health care, institutions should verify that all HCWs have clear evidence of immunity to VZV and should ensure that susceptible subjects will receive 2 doses of VZV vaccine. Currently, the vaccination of HCWs is not compulsory in Italy and the risk of varicella infection among these subjects is not well known. We evaluated the clinical records of 840 HCWs (256 male and 584 female) who underwent the annual occupational screening, from 1st January to 31st August 2018. HCWs were divided into three subgroups according to their age: 18–30, 31–40, and over 40 years old. We compared the mean values of IgG-specific antibodies between the age group through analysis of variance (ANOVA). A total of 784 (93.33%) HCWs were protected for VZV IgG antibodies level. There wasn’t a significant difference between male and female while was found between age group (P < 0.001). Protection levels for varicella are inadequate among HCWs. Despite the epidemiology of varicella in general population has changed with the implementation of the childhood varicella vaccination program transmission of VZV in hospitals is still a serious problem, so it is necessary to increase prevention activities in these settings, including vaccination.

Seasonal Dynamics of Varicella Incidence in Bulgaria

Aim: Spatial and temporal distribution of varicella is heterogenic and insufficiently studied in Europe. The present study tries to fill the gap that exists about the seasonality of the infection in Bulgaria. Materials &amp; methods: A 4-year retrospective study of the monthly and seasonal varicella epidemiology was performed at both national and district level. Results: In Bulgaria, varicella incidence peaked during winter (37% of the 2015–2018 cases), followed by spring (33%) and autumn (23%). Highly populated districts were more likely to follow this pattern, while less inhabited districts with smaller urbanized areas showed different periodicity of the infection. Conclusion: Winter peak in varicella incidence is positively associated with high accumulation of people in the large cities (&gt;75,000 inhabitants).

Epidemiology of varicella and effectiveness of varicella vaccine in Hangzhou, China, 2019

ABSTRACT Background: The varicella vaccine (VarV) is not included in the national childhood immunization schedules in China, although 2-dose VarV (VarV2) were recommended for children at 1 and 4 years of age in Hangzhou since 2014. However, the reported incremental vaccine effectiveness (VE) of VarV2 varies widely among studies. We described the epidemiological characteristics of varicella in Hangzhou, assessed the VE of VarV, so as to provide scientific evidence on optimization and adjustment of immunization strategies for varicella prevention in China. Methods: All varicella cases diagnosed in a hospital in Hangzhou are reported to China Information System for Disease Control and Prevention (CISDCP). The demographic information of reported varicella cases onset from January 1 to December 31, 2019 was extracted from CISDCP on Jan 31, 2020. The demographic information was obtained from the information system of the National Center for Disease Prevention and Control. We conducted a 1:1 matched case–control study to assess the effectiveness of VarV. Participant data were collected with standardized questionnaires. VarV vaccination status was checked by using Hangzhou Immunization Information System (HZIIS). Results: A total of 11,813 varicella cases were reported in Hangzhou, China, 2019, without any death. Annual estimated incidence of varicella was 120 cases per 100,000 populations in 2019. The overall estimated incidence rate of varicella was high, especially for persons aged 10–19 years old and in suburb areas. The seasonal pattern was apparent, mostly due to the cases among students and children in kindergarten. In total, 218 varicella cases and 218 matched controls were included for evaluating the VE of VarV. VarV vaccination produced a high level of protection against varicella, while VE of VarV2 was even better. VE of VarV1 was 91.0% (95%CI: 81.6%-95.8%), and VE was 98.0% (95.5%-99.2%) for VarV2. Conclusion: Continuous monitoring and management of varicella cases is necessary, especially in those endemic areas, high-risk populations, and peak periods; a 2-dose VarV strategy is highly recommended, and relevant health institutions should consider the inclusion of VarV in the national immunization program to better control varicella epidemic and reduce the burden of varicella.

Features of the Epidemiology of Chickenpox in a Single Territory

Relevance.The urgency of the problem of chickenpox is determined by the high incidence, severe complications and the possibility of deaths.The aim of the work is to analyze the peculiarities of the epidemiology of chickenpox in a single territory located in the immediate vicinity of a large metropolis.Materials and methods. A retrospective epidemiological analysis was carried out using official statistics.Results and discussion. It is established that in the study area in 2009–2018 there was a unfavorable epidemic situation for chickenpox. The most vulnerable groups in terms of morbidity are young children, especially those who attend children's organized institutions. In recent years, there has been a trend of increasing morbidity among the adult population. Preventive measures do not have a significant impact on reducing the incidence of chickenpox.Conclusions. The analysis showed the high relevance of the organization of a reliable system of prevention of chickenpox, which should be based on the development and implementation in the practice of health care of domestic vaccine against this infection.