Varicella-zoster Virus Seroprevalence Research Articles

Seroprevalence of varicella-zoster virus among people living with human immunodeficiency virus in Ile-Ife, Nigeria: A cross-sectional study

Seroprevalence of varicella-zoster virus among people living with human immunodeficiency virus in Ile-Ife, Nigeria: A cross-sectional study

Varicella Seroprevalence among Healthcare Workers: A Pilot Study from a Tertiary Care Centre in Northern India

Introduction: Susceptible Healthcare Workers (HCWs) lacking immunity to Varicella Zoster Virus (VZV) can get infected and spread the infection to their patients. Effective screening can help in early vaccination to limit nosocomial transmission of VZV. Aim: To assess the seroprevalence of VZV among HCWs. Materials and Methods: This was a hospital-based pilot study where serum samples were collected from 201 HCWs working in different departments of the Government Medical College, Srinagar, Jammu and Kashmir, India and its eight associated hospitals over a period from January 2021 to February 2021, after obtaining their consent to participate in the study. Samples were tested for VZV Immunoglobulin G (IgG) antibodies using the Enzyme Linked Immuno Sorbent Assay (ELISA) method (NovaLisaVZVIgG, ELISA Kit). Variables including age, sex, professional category, history of varicella infection, and VZV vaccination were collected in a proforma. Statistical analysis was done using Open Epi version 3.01. Results: The overall prevalence of antibodies to varicella was 150/196 (76.53%). HCWs had equivocal results in 4 (2.04%) cases. An age-related increase in seroprevalence was observed. Only 6/196 (3.06%) participants were vaccinated against VZV, and 38/196 (19.39%) participants had a history of VZV infection in the past. Conclusion: The present study found a significant proportion of HCWs susceptible to VZV, making them potentially at risk of acquiring and transmitting the infection. This reinforces the need for screening HCWs against VZV and vaccinating them whenever necessary to protect the patients.

Seroprevalence of VZV and HSV-2 Antibodies among Women of Childbearing Age Referring to Health Centres of Mashhad, Iran: The Need for Consideration of VZV Vaccination Program.

Infections with herpes simplex virus type 2 (HSV-2) and varicella-zoster virus (VZV) are associated with serious maternal and neonatal health consequences. The literature review reveals a research gap regarding the seroprevalence of HSV-2 and VZV among women of reproductive age in Mashhad, Northeast of Iran. The present study aims to evaluate the seroprevalence of these viruses among a group of women in Mashhad, Iran. Sera were collected by health center personnel using a cluster sampling method from healthy women with specific age characteristics residing in three distinct socioeconomic regions of the city. The participants, aged 20-35, were divided into three groups (20-25, 26-30, and 31-35 years). The levels of VZV and HSV-2 IgG antibodies were evaluated using commercial ELISA kits. Subsequently, the results were analyzed using SPSS software. A total of 93 women were included in the study. Anti-HSV-2 IgG antibody was detected in 3 out of 93 participants (7.5%), while anti-VZV IgG antibody was found positive in 80 out of 93 individuals (83.3%). The HSV-2 positive cases were concurrently positive for the VZV antibody. There was no significant difference in the positivity of anti-HSV-2 and anti-VZV antibody positivity within age groups or socioeconomic status (P > 0.05). The high seroprevalence of VZV among nonvaccinated participants indicates a widespread presence of the virus and underscores its potentially serious impact on community health. Therefore, it is recommended that a VZV vaccination program be considered by the health system. Furthermore, the reactivation of latent HSV-2, whether symptomatic or asymptomatic, during pregnancy should not be disregarded as a life-threatening threat.

Comparative gender analysis of the seroprevalence of varicella zoster virus among HIV-infected individuals receiving care at Offa, north-central Nigeria

Background: Varicella zoster virus (VZV) infections are common and contribute substantially to morbidity and mortality among HIV-infected patients. This study was conducted to determine the level of exposure, compare the gender distribution pattern and correlate with CD4 count, history of chicken pox and demographics among HIV patients.
 Methodology: Blood samples were collected from 273 randomly selected HIV-positive patients (93 males and 180 females) receiving care and management at the General Hospital Offa, Kwara State, Nigeria, between September 2019 and March 2020, after obtaining informed consent. Sera were separated from the blood samples and tested for the presence of VZV-specific IgG antibodies using Enzyme Linked Immunosorbent Assay (ELISA).
 Results: The seroprevalence rate of VZV in the selected HIV patients was 76.9% (210/273), which was similar in both male (83.9%, 78/93) and female (73.3%, 132/180) patients (χ2=3.265, p=0.071). The seroprevalence rates of VZV in both male and female patients were significantly associated with marital status, occupational status, and CD4+ cell count (p<0.05), however, age group was not significantly associated with VZV seroprevalence in both male (χ2=8.014, p=0.155) and female (χ2=4.689, p=0.455) patients. The seroprevalence of VZV in males (32%) who reported history of chicken pox was about twice that of females (17.4%) (OR=2.235, 95% CI=1.162-4.302, p=0.023).
 Conclusion: The level of exposure of HIV-infected individuals to VZV in Offa, Nigeria is high and is similarly distributed in both male and female genders. However, more males with VZV exposure reported history of chicken pox (acute infection) than their female counterparts.

Seroprevalence of varicella-zoster virus antibody and immunogenicity of live attenuated varicella vaccine in healthcare workers in Taiwan.

Healthcare workers (HCWs) without evidence of immunity to varicella-zoster virus (VZV) are recommended to undergo varicella vaccination. Immunogenicity of live attenuated varicella vaccine has rarely been investigated among HCWs in Taiwan. Anti-VZV immunoglobulin G (IgG) titer was checked for all HCWs at Changhua Christian Hospital from 2011 to 2017. One-dose and two-dose (separated by 4-8 weeks) vaccines were administered to HCWs with equivocal and negative anti-varicella IgG results, respectively. Follow-up anti-VZV IgG was determined at least 4 weeks after completion of vaccination. Factors associated with seroconversion to varicella vaccination were analyzed. Among 2406 included HCWs, the anti-VZV IgG serostatus was tested positive, equivocal and negative in 1924 (79.9%), 117 (4.9%) and 365 (15.2%), respectively. The seroprevalence had decreased from 88.0% (235/267) in 2011 to 72.2% (270/374) in 2017 (p for trend <0.05). A total of 67.8% (327/482) HCWs completed scheduled vaccination and serological follow-up. The seroconversion rates for HCWs with baseline equivocal and negative anti-VZV IgG results were 100% (80/80) and 79.4% (196/247) after one- and two-dose vaccination, respectively. In multivariate analysis, obesity (adjusted odds ratio, 0.308; 95% confidence interval [CI], 0.11-0.94, p=0.039) was the only factor statistically significantly associated with seroconversion to vaccination. Decreasing trends of seroprevalence of VZV were observed among HCWs from 2011 to 2017. HCWs who were obese were less likely to respond to varicella vaccination.

Exploring human mixing patterns based on time use and social contact data and their implications for infectious disease transmission models

BackgroundThe increasing availability of data on social contact patterns and time use provides invaluable information for studying transmission dynamics of infectious diseases. Social contact data provide information on the interaction of people in a population whereas the value of time use data lies in the quantification of exposure patterns. Both have been used as proxies for transmission risks within in a population and the combination of both sources has led to investigate which contacts are more suitable to describe these transmission risks.MethodsWe used social contact and time use data from 1707 participants from a survey conducted in Flanders, Belgium in 2010–2011. We calculated weighted exposure time and social contact matrices to analyze age- and gender-specific mixing patterns and to quantify behavioral changes by distance from home. We compared the value of both separate and combined data sources for explaining seroprevalence and incidence data on parvovirus-B19, Varicella-Zoster virus (VZV) and influenza like illnesses (ILI), respectively.ResultsAssortative mixing and inter-generational interaction is more pronounced in the exposure matrix due to the high proportion of time spent at home. This pattern is less pronounced in the social contact matrix, which is more impacted by the reported contacts at school and work. The average number of contacts declined with distance. On the individual-level, we observed an increase in the number of contacts and the transmission potential by distance when travelling. We found that both social contact data and time use data provide a good match with the seroprevalence and incidence data at hand. When comparing the use of different combinations of both data sources, we found that the social contact matrix based on close contacts of at least 4 h appeared to be the best proxy for parvovirus-B19 transmission. Social contacts and exposure time were both on their own able to explain VZV seroprevalence data though combining both scored best. Compared with the contact approach, the time use approach provided the better fit to the ILI incidence data.ConclusionsOur work emphasises the common and complementary value of time use and social contact data for analysing mixing behavior and analysing infectious disease transmission. We derived spatial, temporal, age-, gender- and distance-specific mixing patterns, which are informative for future modelling studies.

Epidemiology of Varicella Zoster Virus and Herpes Zoster Virus in Gulf Cooperation Council Countries: A Review of the Literature.

The reactivation of varicella zoster virus (VZV) in previously infected individuals can cause herpes zoster (HZ), which is characterized by a localized, painful dermatomal rash. While there is a global trend of increasing HZ cases, there is a lack of research examining the epidemiology of HZ within the Gulf Cooperation Council (GCC) countries. Therefore, we aimed to critically appraise evidence on VZV and HZ epidemiology in the GCC countries and identify gaps in the current literature. A literature review was conducted via a comprehensive appraisal of the literature. PubMed and local-language journals were searched to identify articles related to HZ and VZV published up until 31 January 2022, with a sole focus on the GCC countries. Included studies reported on surveillance data, seroepidemiology, and patient outcomes for HZ and VZV, and comprised primary data reports, case series, case reports, narrative and systematic literature reviews, studies reporting HZ incidence or prevalence, and Ministry of Health reports. Thirteen studies were found that reported on VZV seroprevalence in Saudi Arabia, the United Arab Emirates (UAE), and Qatar, ranging from 15.0% to 92.2%, while no data were identified for Bahrain, Kuwait, or Oman. There was very limited country-wide information on the incidence of HZ in GCC countries, and three identified studies reported HZ prevalence as seen in a single clinic, ranging from 0.62% to 2.3%. A single study from Saudi Arabia and government surveillance data reported on the impact of VZV vaccination on VZV infection, though there was no evidence on the impact of VZV vaccination on HZ. There is a clear gap in the literature regarding the incidence of HZ infection, and the impacts of HZ and VZV vaccinations in the GCC countries. Further research into the epidemiology of HZ is necessary to inform the implementation of vaccination programs in the GCC countries.

Seroprevalence of Varicella-Zoster Virus and Measles among Healthcare Workers in a Tertiary Medical Center in Korea.

Measles and varicella still occur in the general population despite the widespread vaccination against them, and healthcare workers (HCWs) are still at risk of exposure to these diseases. Here, we evaluated the seroprevalence of measles and varicella-zoster virus (VZV) in HCWs and the trend of seroprevalence according to age, birth year, and occupational group. The serostatuses of measles and VZV of HCWs during new employee medical examinations between October 2015 and October 2021 were included. Thereafter, the trends of seroprevalence according to age, birth year, and occupational groups were evaluated. Overall, 2070 and 1827 HCWs were evaluated for VZV and measles serostatus, respectively. The seroprevalences of VZV and measles were 91% (1884/2070) and 70% (1284/1827), respectively. Younger HCWs had a significantly lower seroprevalence of measles (p = 0.02, age) and VZV (p = 0.003, birth year and p &lt; 0.001, age). The seroprevalence of measles and VZV was significantly higher among doctors and nursing assistants than among nurses and other HCWs (p &lt; 0.001 in both). In conclusion, the seroprevalence of measles and VZV significantly decreased in younger HCWs. Additionally, monitoring the serostatus of measles and VZV and the immunization of susceptible HCWs are required to prepare and control infectious diseases in healthcare facilities.

Impact of varicella vaccination in Argentina: Seroprevalence in children and adults in a pediatric hospital

BackgroundVaricella is the primary infection caused by varicella-zoster virus (VZV). In Argentina, the varicella vaccine was introduced in the National Immunization Programme in 2015 as a single dose scheduled at 15 months of age. ObjectivesTo estimate VZV seroprevalence in a healthy hospital based population before and after vaccine introduction to the NIP. Material y MethodsCross-sectional, observational, analytic study. Healthy subjects 1–40 years of age were included between June and December 2019 and tested for VZV-antibodies. Results were compared to data from a similar prevaccination study. ResultsOut of 599 samples, 11 indeterminate results were excluded, 424 were positive; overall seroprevalence rate was 72.1% (95 %CI = 68,3–75,8%). No differences were observed between pre and post vaccination studies for overall prevalence or between age groups, except for vaccinated children aged 11–15 (p = 0,005). Rates increased in both periods in subjects aged 6 years or older. Primary vaccine failures were 21%; in subjects <5 years 83% seropositive cases had been vaccinated, in >5 year-olds >90% seropositive cases were associated with a history of infection (OR: 10,4; IC95%: 6,4–16,8; p < 0,001) or household contact (OR:4,8; IC95%: 3,1–7,6; p < 0,001). Vaccination protected against disease (OR: 0.25; 95 %CI: 0.09–0.68; p = 0.004). Conclusionseroprevalence was high in all age groups except in unvaccinated 12 to 15-month infants. Seropositivity was due to vaccination in 15 months to 5 year-old children and to infection in older children.

1433. Promoting Vaccination of Vaccine Preventable Diseases in Newly Employed Nurses and Doctors Guided by Serological Study

BackgroundVaccination after serological evaluation of healthcare workers is key component of vaccine preventable diseases (VPDs) preparedness in hospital. The aim of this study is to determine the seroprevalence of VPDs and the vaccination rates among newly employed nurses and doctors.MethodsA cross-sectional study was conducted at a referral university hospital in the Republic of Korea. All newly employed nurses and doctors without immunity were recommended to have the hepatitis B virus (HBV), varicella zoster virus (VZV), measles, mumps, and rubella (MMR), hepatitis A virus (HAV) and tetanus-diphtheria-pertussis (Tdap) vaccination. HBV, VZV, MMR vaccinations were financially supported and Tdap vaccination was recommended without testing. We investigated the seroprevalence of HAV, HBV, and VZV and vaccination rate of recommended vaccination (HAV, HBV, MMR, VZV, and Tdap) from Jan 1st, 2017 to March 31th, 2020.ResultsA total of 668 (527 female, 141 male) newly employed nurses and doctors were identified. The median age (IQR) is 25 (24-27). Seroprevalence were 59.1% (95% confidence interval [CI] 55.4-62.8) for HAV, 86.1% (95% CI 83.5-88.7) for HBV, and 92.4% (95% CI 90.4-94.4) for VZV. Vaccination rate of recommended vaccination were 24.5% (95% CI 18.5-30.5) for HAV, 23.3% (95% CI 13.6-33.0) for HBV, 48.7% (95% CI 33.0-64.4) for VZV, 30.0% (95% CI 25.5-34.5) for MMR and 33.1% (95% CI 29.0-37.2) for Tdap respectively.ConclusionSeroprevalence of HAV was lower than HBV and varicella in newly employed nurses and doctors. Although persistent effort to improve the healthcare worker’s vaccination, the actual rates were low. Further strategy promoting vaccination of newly employed nurses and doctors are needed.Disclosures All Authors: No reported disclosures

Evaluation of Varicella-Zoster Virus Immunoglobulin G in Children With Malignancies on Chemotherapy

Background: Varicella-Zoster Virus (VZV) infection in children with different malignancies on chemotherapy has become an alarming problem. There are insufficient data about VZV seroprevalence among patients in Iran. Objectives: The current study was conducted to assess the seroprevalence of VZV serum IgG antibodies in children with malignancies on chemotherapy. Methods: The current single-center cross-sectional study was conducted from January 2018 to December 2019 at Mofid children’s hospital, Tehran, Iran. Five milliliters of blood samples were collected from the patients. Serum samples were then tested in duplicate for the IgG antibody against VZV using Varicella-Zoster ELISA IgG/IgM kit. Results: A total of 54 children with different malignancies were included. Overall, 24 and 30 serum samples were collected from females and males, respectively. The children were five months to 15-years-old with a mean age of 5.5 years. The overall seroprevalence of VZV IgG in the children was 21.1% (n = 13/54). Of patients with positive VZV IgG antibody, 9 (69.2%) were male, and four (30.8%) were female. Besides, Acute Lymphocytic Leukemia (ALL) with 61.1% (n = 33/54) was the most common underlying malignancy among these patients. The prevalence of anti-VZV IgG antibodies was 21.2% (n = 7/33) in the group of children with ALL. The highest seroprevalence of the VZV IgG antibody was seen in 11 to 15-year-old children (n = 3/7; 42.9%). The prevalence rates of IgG antibodies against VZV among children aged 0-2 years, 3-5 years, and 6-10 years were 28.6%, 25.9%, and 7.7%, respectively. Conclusions: The results showed that children with different malignancies on chemotherapy are quite susceptible to chickenpox infection. It is suggested that a safe and effective live attenuated varicella vaccine in line with the WHO recommendations be incorporated into Iran’s national immunization program for children with various malignancies.

New approaches to controlling an outbreak of chickenpox in a large immigration detention setting in England: the role of serological testing and mathematical modelling.

Chickenpox is caused by varicella-zoster-virus (VZV) and is highly contagious. Immigration detention settings are a high-risk environment for primary VZV transmission, with large, rapidly-changing populations in close quarters, and higher susceptibility among non-UK-born individuals. During outbreaks, operational challenges occur in detention settings because of high-turnover and the potential need to implement population movement restriction for prolonged periods. Between December 2017 and February 2018, four cases of chickenpox were notified amongst 799 detainees in an immigration removal centre (IRC). Microbiological investigations included case confirmation by vesicular fluid polymerase chain reaction, and VZV serology for susceptibility testing. Control measures involved movement restrictions, isolation of cases, quarantining and cohorting of non-immune contacts and extending VZV immunity testing to the wider detainee population to support outbreak management. Immunity was tested for 301/532 (57%) detainees, of whom 24 (8%) were non-immune. The level of non-immunity was lower than expected based on the existing literature on VZV seroprevalence in detained populations in England. Serology results identified non-immune contacts who could be cohorted and, due to the lack of isolation capacity, allowed the placement of cases with immune detainees. The widespread immunity testing of all detainees was proving challenging to sustain because it required significant resources and was having a severe impact on operational capacity and the ability to maintain core business activities at the IRC. Therefore, mathematical modelling was used to assess the impact of scaling back mass immunity testing. Modelling demonstrated that interrupting testing posed a risk of one additional case compared to continuing with testing. As such, the decision was made to stop testing, and the outbreak was successfully controlled without excessive strain on resources. Operational challenges generated learning for future outbreaks, with implications for a local and national policy on IRC staff occupational health requirements, and proposed reception screening of detainees for VZV immunity.

Immunity to varicella zoster virus among pregnant women in the Norwegian Mother and Child Cohort Study.

IntroductionInfection with varicella zoster virus (VZV) in pregnancy may lead to serious outcomes both for the mother and the newborn. Targeted screening and vaccination of non-immune women during reproductive age could prevent varicella infection in pregnancy. Currently, no universal varicella screening of pregnant women is implemented in Norway, but serological testing in pregnancy is recommended in particular situations. We examined seroprevalence of VZV in a national pregnancy cohort in order to help assess a need for VZV screening of women during reproductive age.MethodsWe determined the susceptibility to VZV and the reliability of self-reported history of VZV infection in the Norwegian obstetric population by using a random sample of 1,184 pregnant women from the Norwegian Mother and Child Cohort study (MoBa). The MoBa study included approximately 95,200 pregnant women in Norway between 1998 and 2009. Blood samples taken at gestational week 17–18 were analysed using a commercial enzyme immunoassay for specific IgG antibodies to Varicella-Zoster virus. Second sample taken at birth was tested if the first sample result was negative or equivocal.ResultsOf the 1,184 pregnant women, 98.6% (n = 1,167) were seropositive, 0.83% (n = 10) remained seronegative, and four women (0.34%) seroconverted during their pregnancy. No significant associations were found between serological status and women’s age at birth, gestational age, women’s country of birth and year of child’s birth. One woman reported prior history of varicella, whereas 143 (12.1%) women reported a household exposure to childhood diseases with fever and rash, of which 25 reported exposure to varicella, of which all were seropositive.ConclusionsThe findings support antenatal screening recommendations in Norway advising testing for VZV in pregnant women with unknown immunity to VZV. Further studies are however needed to better identify target groups for screening and vaccination.

Seroprevalence of varicella-zoster virus among pregnant women in Fayoum Governorate, Egypt

BackgroundChickenpox infection acquired during pregnancy is a serious condition. There may be congenital malformations and neonatal varicella syndrome with significant morbidity and mortality. Egypt has no routine varicella-zoster vaccination program.ObjectiveTo assess the immune status against varicella-zoster virus (VZV) antibodies among a group of pregnant women and to study the relationship between VZV seroprevalence and some sociodemographic characteristics.Subjects and methodsA descriptive cross-sectional study was conducted on a group of pregnant women (n = 333) attending antenatal care (ANC) clinic at Fayoum University Hospital. Serologic testing for VZV was performed using ELISA through the years 2016–2017.ResultsVZV seroprevalence was detected in 294 (88.3%) of the 333 recruited pregnant women. Older age > 25 years old was significantly associated with low percent of VZV-negative antibodies (6.7% in versus 17.4% in younger age, OR (95%CI) 0.34 (0.17–0.70)), also having more than one child was significantly associated with a low percent of VZV-negative antibodies (8.2% versus 16.1% among participants with no children or having one child, OR 0.34 (0.17–0.70)).ConclusionsDespite the absence of a routine VZV vaccination program in Egypt, VZV immunity was high among pregnant women, but less than that reported in many developed countries. We recommend targeted vaccination for women in the reproductive age especially young and primipara.Trial registrationEthical Committee Registration number R67 session 42: date 12/11/2017(retrospectively registered).

Epidemiology and factors influencing varicella infections in tropical countries including Sri Lanka.

Varicella zoster virus (VZV) infections occur worldwide but the epidemiology differs between different geographical regions. Epidemiology of varicella is partly understood in tropical and subtropical regions. Various hypotheses showing differences in exposure rates in different age groups have been proposed. Exposure to VZV during late childhood or adolescent stage causes high morbidity, especially in high school children, university students and young work force in tropical nations. Exposure to VZV infection or sero-prevalence rates through anti-VZV immunoglobulin G appears to be lower in Sri Lanka, similar to other tropical countries prior to the millennium. In contrast, a more recent study in a group of antenatal women showed a relatively higher exposure rate to VZV when compared to the exposure rates prior to 2004 in Sri Lanka. Climatic factors, socioeconomic conditions, mobility and cultural practices appear to play a role in the differences in the exposure rates to VZV infection in the tropics. In most tropical Asian countries including Sri Lanka, routine vaccination against varicella is not carried out. Individuals with negative history for varicella take the vaccine when there is a necessity. Medical and nursing students take the vaccine prior to their clinical training to avoid adulthood varicella.

The Seroprevalence of Varicella Zoster Virus in a Healthy Population from Tehran, Iran

Background: Varicella zoster virus (VZV) is responsible for chickenpox, which is generally a mild self-limited disease in healthy children. However, this disease may progress to a complicated and even life-threatening disease in adolescents, young adults, and immunocompromised patients in particular. The present study was conducted to investigate the seroprevalence of VZV in different age groups, selected among residents of Tehran, Iran. Methods: We performed varicella serological tests (IgG) on the serum specimens of healthy people, collected from 3 main laboratories in Tehran. VZV IgG was measured with the ELISA method. We divided the subjects into 6 subgroups: below 2 years, 2 - 5 years, 5 - 12 years, 12 - 19 years, 19 - 25 years, and above 25 years. We tested almost 95 specimens from each age group. Results: Samples were collected from 570 individuals, including 231 males. The VZV IgG was positive in 393 subjects; cumulatively, 81.3% of the population were immune to VZV. The seroprevalence rate was 43.2% in infants below 2 years, 32.6% in children aged 2 - 5 years, 47.2% in children aged 5 - 12 years, 74.7% in adolescents aged 12 - 19 years, 83.2% in young adults up to 25 years, and 90.5% in adults > 25 years. Conclusions: Although the cumulative seroprevalence was estimated at 81.3% for all age groups, this rate was only 43% in children below 12 years; therefore, adolescents and young adults (high-risk age groups) are prone to chickenpox infection. In order to protect individuals against this infection, we suggest well-designed studies to address the need for routine chickenpox immunization programs in young children.

Seroprevalence of varicella zoster virus in Colombo district, Sri Lanka

Objective: To determine the seroprevalence of varicella zoster virus (VZV) antibodies among the population residing in the Colombo district of Sri Lanka. Methods: A cross-sectional population-based study was conducted which included 1 258 participants. Blood samples were collected and questionnaires administered to obtain sociodemographic information and history of varicella and/or herpes zoster. Serum samples were assayed for VZV IgG antibodies using a commercial enzyme-linked immunosorbent assay kit. Results: Overall, the seroprevalence was 54.2% (95% CI = 51.5% 57.0%). Children below 1 year of age were seronegative, and only about 20.0% of children between 1 and 10 years of age were seropositive. Seropositivitiy increased with age and by the age of 40 years 74.3% were seropositive. Among women of childbearing age, the overall seroprevalence was about 62.0% (95% CI = 57.7%-66.1%) but was low 37.0% in the 15-19 age group. Conclusion In this population, 45.8% lacked natural immunity against varicella. Of women of childbearing age, 39.9% lacked immunity and in the subgroup of women 15-19 years of age, 63.0% women lacked immunity. In light of the country's success with the control and high coverage of other vaccine preventable diseases and that the vaccine is available in the private sector, the inclusion of varicella vaccine in the national immunization program may be considered.

Seroprevalence of Varicella Zoster Infection at Provincial Level in Iranian Adolescents: The CASPIAN-III Study

Background: Although primary varicella zoster virus (VZV) infection (chicken pox) is a mild childhood disease, it can cause severe infection with complications in adults. As the disease is preventable by effective vaccination, it is important to determine the level of immunity to VZV in every region to implement proper vaccination strategies. Objectives: The aim of this study was to investigate the seroprevalence of VZV infection in adolescents living in different provinces of Iran. Methods: In a cross-sectional multicentre study, serum samples from 2315 students, aged 10 - 18 years, were examined for VZV antibodies (IgM/IgG). Students were selected by multistage cluster sampling during a national surveillance program. Results: Prevalence of VZV antibodies was statistically different in various provinces of Iran (P = 0.001); it ranged from 82.4% in Isfahan, Center of Iran, to 98.5% in Mazandaran, North of the country. The VZV seroprevalence was not significantly different by gender, except for Khuzestan, South of Iran, where antibodies were much more prevalent in girls (92.7%) than in boys (78.3%, P = 0.004). Seroprevalence was not significantly different according to the living area (urban/rural). Conclusions: VZV seroprevalence is different in various provinces of Iran; the susceptibility of adult population to VZV infection is suggested to be high in Ardabil, Isfahan, and Kermanshah; and low in Kerman and Mazandaran. Therefore, different strategies should be implemented in each province to protect high-risk adults from severe varicella infection.

Varicella-zoster virus seroprevalence in children and adolescents in the pre-varicella vaccine era, Germany

BackgroundIn 2004, universal childhood varicella vaccination was introduced in Germany. We aimed to determine the age-specific prevalence of anti-varicella zoster virus (VZV) IgG-antibodies among children in the pre-varicella vaccine era in Germany, to identify factors associated with VZV seropositivity, and to assess the suitability of a commercially available ELISA for VZV seroepidemiological studies by comparing it with an in-house fluorescent antibody to membrane antigen test (FAMA) as the gold standard.MethodsSerum samples of 13,433 children and adolescents aged 1–17 years included in the population-based German Health Interview and Examination Survey for Children and Adolescents (KiGGS; conducted 2003–2006) were tested for anti-VZV IgG by ELISA. All samples with equivocal ELISA results and a random selection of ELISA-negative and -positive samples were tested by FAMA. Statistical analyses were conducted using a weighting factor adjusting the study population to the total population in Germany. Seroprevalences were calculated as percentages (%) with a 95% confidence interval (CI). Odds ratios (OR) were computed by multivariate logistic regression to determine the association between socio-demographic factors and VZV seropositivity.ResultsThe VZV seropositivity rate was 80.3% (95% CI: 79.3–81.3) in varicella-unvaccinated children and adolescents. VZV seropositivity rates differed significantly between age groups up to age 6 years, but not by gender. Of 118 retested serum samples with an equivocal ELISA result, 45.8% were FAMA-positive. The proportion of samples tested as false-negative in by ELISA varied by age group: 2.6% in children aged 1–6 and 9% in children aged 7–17 years. Multivariate analyses showed that age, having older siblings, and early daycare start were associated with seropositivity in preschoolers; migration background reduced the chance of VZV seropositivity in schoolchildren (OR: 0.65; 0.43–0.99) and adolescents (OR: 0.62; 0.4–0.97).ConclusionIn the pre-varicella vaccine era, most children in Germany contracted varicella by age six. Schoolchildren with a migration background and children without siblings have an increased risk of being VZV seronegative and should be targeted for catch-up vaccination, if they have no history of chickenpox. ELISAs are suitable for use in population-level serosurveys on VZV, but samples with equivocal ELISA results should be retested by FAMA.

Seroprevalence and Risk Factors of Varicella Zoster Infection in Iranian Adolescents: A Multilevel Analysis; The CASPIAN-III Study.

The objective of this study was to evaluate the varicella zoster virus (VZV) immunity in Iranian adolescents. It was conducted as a primary study for vaccine implementation, and to investigate the association of climatic and socioeconomic factors with the epidemiology of this infection. In this cross- sectional study, anti VZV antibodies were measured in serum samples obtained in a national school-based health survey (CASPIAN- III). Association of demographic, socio-economic, and climate of the living region with the frequency of VZV was investigated by multivariate multilevel analysis. Overall, sera of 2753 individuals aged 10–18 were tested for VZV antibodies, from those 87.4% were positive. The prevalence was statistically different in four socio-geographic regions (P<0.001), varying between 85.24% in West region (mostly mountainous areas with cold climate) to 94.59% in Southeast region (subtropical climate). Among variables studied, only age and mean daily temperature of the living area were positively associated with the VZV seroprevalence. Our findings show that most Iranians develop immunity to VZV before the age of 10, but a substantial proportion of them are yet susceptible to the infection. Therefore, it seems that the best strategy to reduce the burden of the disease is to vaccinate high- risk adults, i.e. those without a history of varicella infection. The regional temperature might be the only determinant of VZV epidemiology in Iran.