The reported incidence of varicella in Beijing from 2019 to 2021 were 63.8/100 000, 32.2/100 000 and 38.6/100 000, respectively. There were two VZV epidemics in Beijing each year, one peaked in May and the other in November. However, the first VZV epidemic almost disappeared in 2020. Among the cases involved in the varicella outbreaks in school, the proportion of the students with no history of vaccine immunization, 1 dose of immunization and 2 doses of immunization were 33.12%, 44.79% and 22.08%, respectively. The major body of VZV breakthrough cases was children aged 6-14 years (523/755, 69.27%). The proportion of moderate- or severe-rash were 55.32%, 39.06%, 29.96% in the three groups of cases with no immunization history, 1 dose of immunization and 2 doses of immunization, respectively (P<0.001). A total of 1 089 varicella samples were collected, and 837 (76.86%) were confirmed to be PCR-positive for VZV and were identified as VZV wild strains. 311 VZV strains were sequenced successfully, and 307 strains were clade 2 (98.72%), 1 clade 3 (0.32%) and 3 Clade 5 (0.96%). Compared with the representative strains, the nucleotide similarities of ORF22 fragments were between 99.4% and 100%, and amino acid similarities were between 99.4% and 100%.
Beijing/epidemiology* ; Chickenpox/epidemiology* ; Chickenpox Vaccine ; Child ; Herpesvirus 3, Human/genetics* ; Humans ; Schools ; Vaccination

OBJECTIVETo study the epidemiological impact of varicella vaccine vaccination on kindergartens and school children in Beijing.

METHODSAccording to "China Information System for Diseases Control and Prevention", the reported clinical diagnosis varicella cases were tracked in kindergartens, primary and secondary schools whose onset date were from 2008 to 2010. Epidemiological survey was conducted and epidemiological features were analyzed.

RESULTSA total of 21 474 varicella cases were investigated: 55.3% (11 883 cases) had been vaccinated by varicella vaccine. Of cases with definite immunization history, interval between vaccination date and onset date were from 30 days to 1 year accounted for 3.4% (286/8510), 1 to 3 years accounted for 18.2% (1551/8510), 3 to 5 years accounted for 28.6% (2431/8510), 5 to 10 years accounted for 34.3% (2916/8510) (left-closed right-open interval); The peak age of onset was 4 years old in cases without immunization history, which was 6 years old in cases with immunization history; The proportion of cases with immunization history (≥ 30 days) had increased from 42.4% (2862/6754) in 2008 to 56.3% (4327/7679) in 2010. The cases with no fever had a higher proportion (54.9%, 6413/11 679) of immunization history (≥ 30 days) than cases with fever (47.7%, 4533/9500) (P < 0.01); The cases with rashes less than 50 had a higher proportion (57.4%, 8045/14 020) of immunization history (≥ 30 days) than cases with rashes more than 50 (40.2%, 2902/7216) (P < 0.01).

CONCLUSIONVaricella vaccine delays the peak age of onset, alleviates the symptoms. The current immunization strategy can not block varicella spread in kindergartens, primary and secondary schools.

Adolescent ; Chickenpox ; epidemiology ; prevention & control ; Chickenpox Vaccine ; Child ; Child, Preschool ; China ; epidemiology ; Female ; Humans ; Male ; Schools ; Schools, Nursery

Objective: To analyze the differences between adults and children in the epidemic characteristics and clinical manifestations of chickenpox and provide a reference for the prevention strategy adjustment of chickenpox. Methods: The incidence data of chickenpox surveillance in Shandong Province from January 2019 to December 2021 were collected. Descriptive epidemiological methods were used to analyze the distribution of cases, and the chi-square test was used to compare the differences in epidemiological characteristics and clinical manifestations of varicella cases between adults and children. Results: A total of 66 182 cases of chickenpox were reported from 2019 to 2021, including 24 085 cases of adults chickenpox, the male to female sex ratio was 1∶1 (12 032∶12 053), basically the same for men and women, and 42 097 cases of children chickenpox, with a gender ratio of 1.4∶1, the male to female ratio was 1.4∶1 (24 699∶17 398). Fever in chickenpox cases was mainly low and moderate, but the proportion of moderate fever with temperature between 38.1 and 39.0 ℃ in children cases (35.0%,14 744/42 097) was significantly higher than that in adults (32.0%,7 696/24 085). The number of herpes in chickenpox cases was mainly less than 50, but the proportion of severe cases with 100-200 herpes in children was higher than that in adults. The incidence rate of complications was 1.4% (333/24 085) in adults chickenpox, the incidence rate of complications was 1.7% (731/42 097) in children chickenpox. The incidence of encephalitis and pneumonia in children was higher than in adults, and the difference was statistically significant (P<0.05). The proportion of chickenpox cases was mainly outpatient, but the hospitalization rate of children cases was 14.4% (6 049/42 097), higher than that of adults, which was 10.7% (2 585/24 085). Conclusions: There were differences between adult chickenpox and child chickenpox in terms of epidemic and clinical manifestations; the symptoms of child chickenpox were more serious than adult chickenpox. However, the adult chickenpox population is generally susceptible and lacks immune strategy protection, which calls for more attention.
Child ; Humans ; Adult ; Male ; Female ; Infant ; Chickenpox/prevention & control* ; Hospitalization ; Incidence ; Pneumonia/epidemiology* ; Epidemics ; Fever/epidemiology* ; Chickenpox Vaccine

PURPOSE: Although varicella outbreakes have frequently occured, the epidemiology of varicella in Korea has not well been delineated. Furthermore without enough investigation with regard to safety and efficacy of varicella vaccine in Korean population, the vaccine has begun to be used in healthy children. Therefore the authors analized the clinical features of patients diagnosed of varicella to aid in understanding the epidemiology of varicella in Korea, and also compared the difference depending on varicella vaccination status. METHODS: The study population consisted of 1154 otherwise healthy patients diagnosed of varicella by six private pediatricians (5 in Seoul and 1 in Incheon) from March 1994 to February 1996. The information pertaining to clinical features of varicella was obtained through questionnaires answered by pediatricians. RESULTS: 1) Among the total 1154 patients, sex ratio was 1.2:1 with male predominance. The average age was 4.1+/-2.5 years old with the range of 1 month to 15 years of age. One thousand and thirty patients (89.2%) were younger than 6 years old and 126 patients (10.9%) were younger than 1 year old. 2) Occurrence of varicella was reported every month during the study period and peak in June, July, and November to January. 3) Two hundreds and eight-four patients (24.6%) had a history of previous varicella vaccination. 4) Four hundreds and fifty-five patients (53.3%) had a history of exposure to patients with varicella and the mean incubation period was 13.7+/-4.1 days with no difference according to varicella vaccination status. 5) Prodromal symptoms were reported from 615 patients (53.3%) with temperature elevation being most frequent. Except for temperature elevation, occurrence of all other prodromal symptoms was not different between unvaccinated and vaccinated patients. 6) Duration of new rash development was 3.9+/-1.3 days with the range of 1 to 9 days and longer in unvaccinated patients (4.1+/-1.2 days) compared to vaccinated patients (3.1+/-1.1 days). Atypical rash was observed in 144 patients (12.5%) and more frequently among unvaccinated patients. 7) Sixty-eight patients suffered from complications which were skin infection (49), conjunctivitis (20), neurologic complication (1), and pneumonia (1), with no difference between unvaccinated and vaccinated patients. CONCLUSIONS: The current study is reporting, for the first time, the epidemiologic features of varicella in Korea. Bedsides, the result of the study, illustrating that 1/4 of the patients reported to have varicella were vaccinated with varicella vaccine, indicates the necessity of the investigation for the safety and efficacy of the vaccine in Korean population.
Chickenpox Vaccine ; Chickenpox* ; Child ; Conjunctivitis ; Epidemiology* ; Exanthema ; Humans ; Korea* ; Male ; Pneumonia ; Prodromal Symptoms ; Surveys and Questionnaires ; Seoul ; Sex Ratio ; Skin ; Vaccination

OBJECTIVEforecast the epidemic trend and to evaluate the effect of outbreak control measures by investigation of a varicella outbreak event with a discrete time delay SEIR model.

METHODSA discrete time delay model was formulated by discretization method based on a continuous SEIR model with the consideration of the time delay effect on latent period and communicable period. The epidemic trend forecast was carried out based on the number of expected cases. The theoretical effect evaluation was assessed by comparing the results from different emergency control measures.

RESULTSWithout any control measures, the theoretical attack rate was 30.16% (504/1671). The course of the epidemic lasted for 4 months and the peak epidemic time was 78 days after the onset of the first case. 'Generation' phenomenon had been observed in the course of the epidemic with the interval of two weeks. The actual number of cases was decreased by 89.48% (451/504) compared with the number of expected cases under no control measure scenario. With the rigorous quarantine measure for all cases on their onset day, when the measure was conducted on 0, 14, 28, 42 days after the onset of the first case, the total numbers of expected cases were 22, 59, 127 and 220 respectively. With the quarantine measure conducted on 14 days after the onset of the first case, when the proportion of quarantine was 30%, 50%, 70%, 90%, the total number of expected cases were 485, 457, 386 and 169, respectively. With the emergent vaccination for all persons, when the measure was conducted on 0, 14, 28, 42 days after the onset of the first case, the total numbers of expected cases were 7, 26, 81 and 202 respectively. With the emergent vaccination conducted on 14 days after the onset of the first case, when the immunization coverage rate was 30%, 50%, 70%, 90%, the total numbers of expected cases were 354, 246, 127 and 40, respectively.

CONCLUSIONThe number of expected cases can be regarded as the reference to evaluate the effect of control measures. The simulation results suggest that it will get more benefits to conduct control measures earlier in varicella outbreak events, and the effect of emergent vaccination is better than that of quarantine measure under the same conditions.

Chickenpox ; epidemiology ; prevention & control ; Communicable Disease Control ; methods ; Disease Outbreaks ; prevention & control ; Humans ; Incidence ; Models, Theoretical

Chickenpox ; prevention & control ; Chickenpox Vaccine ; therapeutic use ; Child ; China ; epidemiology ; Communicable Disease Control ; methods ; Disease Outbreaks ; prevention & control ; Female ; Humans ; Male ; Schools ; Students

Varicella, which is mostly a benign disease, but also can cause considerable health burden in the community, can be prevented by immunization with live attenuated varicella vaccine. Higher uptake of varicella vaccine by universal immunization in North America has apparently been associated with decline in the number of reported cases of varicella, varicella-related hospitalizations, and the number of deaths caused by complications of varicella. On the contrary, there has been some reluctance in endorsing varicella vaccine for universal immunization in most of European countries. Concerns include unanticipated outbreaks of varicella among vaccine recipients, risk of varicella among unvaccinated adults, risk of herpes zoster among vaccinees as well as unvaccinees. Recently developed measles, mumps, rubella, and varicella combination vaccine and herpes zoster vaccine that may be licensed in the upcoming years may be the solution for varicella vaccine to be utilized in a greater scale. In Korea several varicella vaccine products have been utilized since late 1980. The adoption of varicella vaccine for universal immunization since 2005 along with the changing view in varicella prevention strategy mandates more studies for immunogenecity and efficacy of varicella vaccines as well as more surveillance to delineate the changes in epidemiology of varicella in Korea.
Adult ; Chickenpox Vaccine ; Chickenpox* ; Disease Outbreaks ; Epidemiology ; Herpes Zoster ; Herpes Zoster Vaccine ; Hospitalization ; Humans ; Immunization ; Korea ; Measles ; Mumps ; North America ; Rubella ; Vaccination* ; Vaccines

OBJECTIVETo understand clinical features of in-patients with varicella and complications in our hospital during 1980-1999.

METHODSAge distribution, season characteristics, complication, occurrence of hospitalized varicella patients in 1980-1999 were analyzed.

RESULTSVaricella mainly occurred in pre-school and school children, most cases were seen in winter and spring. There were 240 hospitalized varicella patients, 160 of whom had complications, 126 patients scattered in 1994-1996 (78.75%). The most often seen complication was skin infection which occurred in 71 patients (44.38%); the second was encephalitis, which occurred in 29 patients (18.12%).

CONCLUSIONSThe occurrence of varicella increased and the disease seemed to be more serious.

Adolescent ; Age Distribution ; Chickenpox ; complications ; epidemiology ; Child ; Child, Preschool ; China ; epidemiology ; Encephalitis ; etiology ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Retrospective Studies ; Skin Diseases, Infectious ; etiology

OBJECTIVE: To investigate the level of IgG antibody to varicella in the healthy population aged 1-19 years in Harbin, China. METHODS: Random sampling was performed to select 1 203 healthy individuals aged 1-19 years in Harbin. According to age, they were divided into ≥1 years group (n=240), ≥4 years group (n=396), ≥7 years group (n=364) and 14-19 years group (n=203). Enzyme-linked immunosorbent assay was used to measure the concentration of varicella-zoster virus (VZV)-IgG antibody in serum, and a concentration of VZV-IgG antibody of ≥100 mIU/mL was considered positive, suggesting that the subject had the ability to resist VZV infection. RESULTS: The overall positive rate of VZV-IgG antibody was 71.49% (860/1 203), and the concentration of VZV-IgG antibody was 447±17 mIU/mL. The concentration of VZV-IgG antibody tended to increase with age (P<0.05). The positive rate of VZV-IgG antibody in the urban population was significantly higher than that in the rural population (P<0.05). There was significant difference in the positive rate of VZV-IgG antibody between the populations with different doses of varicella vaccination (P<0.05), and the population with 2 doses of vaccination had the highest positive rate of VZV-IgG antibody. There was a significant difference in the concentration of VZV-IgG antibody between the populations with different medical histories (P<0.05), and the population with a past history of varicella had the highest concentration. CONCLUSIONS Among the healthy population aged 1-19 years in Harbin, there is a significant difference in the level of VZV-IgG antibody between the urban and rural populations, as well as between different age groups. Varicella vaccination should be strengthened in areas with a low vaccination rate and the population aged <14 years.
Adolescent ; Adult ; Antibodies, Viral ; Chickenpox ; epidemiology ; Child ; Child, Preschool ; China ; epidemiology ; Herpesvirus 3, Human ; Humans ; Immunoglobulin G ; Infant ; Seroepidemiologic Studies ; Young Adult

OBJECTIVES: Although the nationwide inoculation rate of varicella vaccine was approximately 95% in Korean children recently, the number of notified varicella cases is unexpectedly continuously increasing till now. To suggest some hypotheses regarding this discrepancy, an age-period-cohort (APC) analysis as a descriptive epidemiology study was conducted for children residing in Jeju-do, Korea.METHODS: The raw data were obtained from the nationwide database for insurance claim of healthcare fee provided by the National Health Insurance Service, Korea. The selection criteria were children aged 2–13 years who visited any healthcare center due to varicella from 2005 to 2016 while residing in Jeju-do. After calculating the birth cohort-specific crude incidence rates by age and year, the intrinsic estimator method was used to perform the APC analysis.RESULTS: As the annual crude incidence rates decreased with increasing age between 2005 and 2016, the age and period effects also decreased. The intrinsic estimator coefficients suggesting the cohort effect shifted from positive to negative in 2011, the starting year of free varicella vaccine program in Jeju-do.CONCLUSIONS: The results suggested that inoculated varicella vaccines have preventive effects. However, further studies to evaluate waning immunity would be needed.
Chickenpox Vaccine ; Chickenpox ; Child ; Cohort Effect ; Delivery of Health Care ; Epidemiology ; Fees and Charges ; Humans ; Immunization Programs ; Immunization Schedule ; Incidence ; Insurance ; Jeju-do ; Korea ; Measles-Mumps-Rubella Vaccine ; Methods ; National Health Programs ; Parturition ; Patient Selection ; Vaccines