Seroprevalence of measles, rubella, and mumps antibodies in Catalonia, Spain: results of a cross-sectional study

The conneXion between sex and immune responses

There are notable sex-based differences in immune responses to pathogens and self-antigens, with female individuals exhibiting increased susceptibility to various autoimmune diseases, and male individuals displaying preferential susceptibility to some viral, bacterial, parasitic and fungal infections. Although sex hormones clearly contribute to sex differences in immune cell composition and function, the presence of two X chromosomes in female individuals suggests that differential gene expression of numerous X chromosome-linked immune-related genes may also influence sex-biased innate and adaptive immune cell function in health and disease. Here, we review the sex differences in immune system composition and function, examining how hormones and genetics influence the immune system. We focus on the genetic and epigenetic contributions responsible for altered X chromosome-linked gene expression, and how this impacts sex-biased immune responses in the context of pathogen infection and systemic autoimmunity.

Immune Cells, Gut Microbiota, and Vaccines: A Gender Perspective

The development of preventive and therapeutic vaccines has played a crucial role in preventing infections and treating chronic and non-communicable diseases, respectively. For a long time, the influence of sex differences on modifying health and disease has not been addressed in clinical and preclinical studies. The interaction of genetic, epigenetic, and hormonal factors plays a role in the sex-related differences in the epidemiology of diseases, clinical manifestations, and the response to treatment. Moreover, sex is one of the leading factors influencing the gut microbiota composition, which could further explain the different predisposition to diseases in men and women. In the same way, differences between sexes occur also in the immune response to vaccines. This narrative review aims to highlight these differences, focusing on the immune response to vaccines. Comparative data about immune responses, vaccine effectiveness, and side effects are reviewed. Hence, the intricate interplay between sex, immunity, and the gut microbiota will be discussed for its potential role in the response to vaccination. Embracing a sex-oriented perspective in research may improve the efficacy of the immune response and allow the design of tailored vaccine schedules.

SARS-CoV-2 spike IgG titres up to 137 days following Comirnaty mRNA COVID-19 vaccination, Israel, February to May 2021

Background

Data regarding the long-term protection afforded by vaccination for the SARS-CoV-2 infection are essential for allocation of scarce vaccination resources worldwide.

Methods

We conducted a retrospective cohort study aimed at studying the kinetics of IgG antibodies against SARS-CoV-2 in COVID-19-naïve patients fully vaccinated with two doses of Comirnaty mRNA COVID-19 vaccine. Geometric mean concentrations (GMCs) of antibody levels were reported. Linear models were used to assess antibody levels after full vaccination and their decline over time.

Results

The study included 4,740 patients and 5,719 serological tests. Unadjusted GMCs peaked 28–41 days after the first dose at 10,174 AU/mL (95% CI: 9,211–11,237) and gradually decreased but remained well above the positivity cut-off. After adjusting for baseline characteristics and repeated measurements, the antibodies half-life time was 34.1 days (95% CI: 33.1–35.2), and females aged 16–39 years with no comorbidities had antibody levels of 20,613 AU/mL (95% CI: 18,526–22,934) on day 28 post-first-dose. Antibody levels were lower among males (0.736 of the level measured in females; 95% CI: 0.672–0.806), people aged 40–59 (0.729; 95% CI: 0.649–0.818) and ≥ 60 years (0.452; 95% CI: 0.398–0.513), and patients having haematological (0.241; 95% CI: 0.190–0.306) or solid malignancies (0.757; 95% CI: 0.650–0.881), chronic kidney disease with glomerular filtration rate (GFR) ≥ 30 (0.434; 95% CI: 0.354–0.532) or with GFR < 30 mL/min (0.176; 95% CI: 0.109–0.287), and immunosuppression (0.273; 95% CI: 0.235–0.317). Body mass index, cardiovascular disease, congestive heart failure, chronic obstructive pulmonary disease, diabetes and inflammatory bowel diseases were not associated with antibody levels.

Conclusions

Vaccination with two doses resulted in persistently high levels of antibodies (≥ cut-off of 50 AU/mL) up to 137 days post-first-dose. Risk factors for lower antibody levels were identified.

The Concordance between Mumps and Rubella Sero-Positivity among the Israeli Population in 2015

Mumps and rubella are vaccine-preventable viral diseases through the measles-mumps-rubella-varicella (MMRV) vaccine, administered at 12 months and again at 6 years. We assessed the sero-prevalence of mumps and rubella, identified factors associated with sero-negativity, and evaluated concordance between mumps and rubella sero-positivity. A national cross-sectional sero-survey was conducted on samples collected in 2015 by the Israel National Sera Bank. Samples were tested for mumps and rubella IgG antibodies using an enzyme-linked immunosorbent assay. Of 3131 samples tested for mumps IgG, 84.8% (95%CI: 83.5–86.0%) were sero-positive. Sero-negativity for mumps was significantly associated with age (high odds ratios observed in infants younger than 4 years and 20–29 years old subjects). Of 3169 samples tested for rubella IgG antibodies, 95.2% (95%CI: 94.4–95.9%) were sero-positive. Rubella sero-negativity was significantly associated with age (high odds ratios observed in children younger than 4 years old and adults older than 30 years), males, Jews, and others. Concordant sero-positivity for both mumps and rubella viruses was observed in 83.9% of the tested samples. The Israeli population was sufficiently protected against rubella but not against mumps. Since both components are administered in the MMRV vaccine simultaneously, the mumps component has a lower uptake than rubella and quicker waning.

Gender differences in measles incidence rates in a multi-year, pooled analysis, based on national data from seven high income countries

Background

Gender differences in a number of infectious diseases have been reported. The evidence for gender differences in clinical measles incidence rates has been variable and poorly documented over age groups, countries and time periods.

Methods

We obtained data on cases of measles by sex and age group over a period of 11–27 years from seven countries. Male to female incidence rate ratios (IRR) were computed for each year, by country and age group. For each age group, we used meta-analytic methods to combine the IRRs. Meta-regression was conducted to the estimate the effects of age, country, and time period on the IRR.

Results

In the age groups < 1, 1–4, 5–9, 10–14, 15–44, and 45–64 the pooled IRRs (with 95% CI) were 1.07 (1.02–1.11), 1.10 (1.07–1.14), 1.03 (1.00–1.05), 1.05 (0.99–1.11), 1.08 (0.95–1.23), and 0.82 (0.74–0.92) respectively. The excess incidence rates (IR) from measles in males up to age 45 are remarkably consistent across countries and time-periods. In the age group 45–64, there is an excess incidence in women.

Conclusions

The consistency of the excess incidence rates in young males suggest that the sex differences are more likely due to physiological and biological differences and not behavioral factors. At older ages, differential exposure can play a part. These findings can provide further keys to the understanding of mechanisms of infection and tailoring vaccination schedules.

Potential immunological effects of gender-affirming hormone therapy in transgender people - an unexplored area of research

There are well-described sex-based differences in how the immune system operates. In particular, cisgender (cis) females have a more easily activated immune system; associated with an increased prevalence of autoimmune diseases and adverse events following vaccinations. Conversely, cis males have a higher threshold for immune activation, and are more prone to certain infectious diseases, such as coronavirus disease (COVID-19). Oestrogen and testosterone have immune-modulatory properties, and it is likely that these contribute to the sexual dimorphism of the immune system. There are also important immune-related genes located on the X chromosome, such as toll-like receptor (TLR) 7/8; and the mosaic bi-allelic expression of such genes may contribute to the state of immune hyperactivation in cis females. The scientific literature strongly suggests that sex-based differences in the functioning of the immune system are related to both X-linked genes and immune modulation by sex hormones. However, it is currently not clear how this impacts transgender (trans) people receiving gender-affirming hormonal therapy. Moreover, it is estimated that in Australia, at least 2.3% of adolescents identify as trans and/or gender diverse, and referrals to specialist gender-affirming care are increasing each year. Despite the improving social awareness of trans people, they remain chronically underrepresented in the scientific literature. In addition, a small number of case studies describe new onset autoimmune disorders in adult trans females following oestrogen use. However, there is currently minimal long-term research with an immunological focus on trans people. Therefore, to ensure the positive health outcomes of trans people, it is crucial that the role of sex hormones in immune modulation is investigated further.

Mumps virus-specific immune response outcomes and sex-based differences in a cohort of healthy adolescents

Despite high levels of MMR-II usage in the US, mumps outbreaks continue to occur. Evidence suggests that mumps vaccine-induced humoral immunity wanes over time. Relatively few studies have examined cell-mediated immunity or reported on sex-based differences. To better understand sex-based differences in the immune response to mumps vaccine, we measured neutralizing antibody titers and mumps-specific cytokine/chemokine responses in a cohort of 748 adolescents and young adults after two doses of MMR vaccine. We observed significantly higher neutralizing antibody titers in females than in males (120.8 IU/mL, 98.7 IU/mL, p = 0.038) but significantly higher secretion levels of MIP-1α, MIP-1β, TNFα, IL-6, IFNγ, and IL-1β in males compared to females. These data demonstrate that sex influences mumps-specific humoral and cell-mediated immune response outcomes, a phenomenon that should be considered during efforts to improve vaccines and prevent future outbreaks.

Safety of measles, rubella and mumps vaccines in adults: a prospective cohort study

BACKGROUND

In recent years, multiple outbreaks of measles associated with vaccine hesitancy occurred in high-income countries, where measles incidence had previously been low. Most safety data about the measles, mumps and rubella (MMR) vaccine are derived from studies conducted among children, whereas evidence regarding the safety profile of the vaccine in adults is scarce.

METHODS

In 2017, during an outbreak of measles in Europe, Israeli travellers to high-risk locations who were incompletely vaccinated, were urged to complete the two MMR vaccination schedule before their travel. In this prospective cohort study, we analysed adverse events (AEs) of MMR and MMRV (measles, mumps, rubella and varicella) vaccines among these travellers. All participants were followed up using structured questionnaires 2-4 weeks after vaccination.

RESULTS

Seven hundred and eighty-five adult travellers whose median age was 49.2 years were vaccinated and followed up. Any AEs were reported by 25.2% of all participants; 11.6% reported local AEs, and 18.6% reported systemic AEs, none of which were severe. In general, AEs were much more common among female travellers (19.4% of males vs 30.1% of females (P < 0.001)). Local AEs, overall systemic AEs, headache and arthralgia were much more common among females, whereas rates of general malaise and fever were not statistically different between genders. We did not observe any significant differences in the rates of total, local or systemic AEs between the MMR and MMRV vaccines. Higher rates of systemic AEs were observed among participants who were younger and probably immunized once with MMR compared to older vaccines immunized once to measles only and to those who were never immunized.

CONCLUSIONS

The current study demonstrated low rates of systemic AEs and no serious AEs following either MMR or MMRV administration. More AEs were reported among females, and rates of AEs were similar after either MMR or MMRV.

Gender Differences in the Level of Antibodies to Measles Virus in Adults

Individuals without a protective antibody level are susceptible to measles infection. There are differences in the persistence of antibodies after vaccination and infection, while the impact of gender on this process has not been sufficiently studied. Measles Ig G antibodies were measured in 1742 employees of a large hospital facility-403 men and 1339 women aged from 25 to 67 years; 15% participants had antibody levels less than the protective threshold of ≥0.18 IU/mL. Significant differences were found in the age group 40-49, where the level of IgG antibodies to measles among men was higher than among women (1.51 IU/mL (0.41; 3.38) vs. 0.70 IU/mL (0.22;1.98) respectively, (U = 3.2, p = 0,001)); in the age group 60 and older, by contrast, the level of antibodies among women was higher compared to men (3.29 IU/mL (1.72; 4.07) vs. 2.90 IU/mL (1.46; 3.53) respectively (U = 2.2, p = 0.03)). The proportion of seronegative women in the age group 40-49 was significantly higher than of seronegative men: 22 [18-26]% and 11 [6-18]% respectively (χ2 = 7.0, p = 0.001). The revealed gender characteristics that affect persistence of measles immunity may be important in personalization of vaccinal prevention for men and women.

Time to get ill: the intersection of viral infections, sex, and the X chromosome

Females have more robust immune responses than males, and viral infections are more severe for males. Hormones and genetic sex, namely the X chromosome, influence sex differences with immune responses. Here, we review recent findings underlying sexual dimorphism of disease susceptibility for two prevalent viral infections, influenza and SARS-CoV-2, which exhibit male-biased disease severity. Viral infections are proposed to be an initiating event for autoimmunity, which exhibits a female bias. We also review recent work elucidating the epigenetic and genetic contribution of X-Chromosome Inactivation maintenance, and X-linked gene expression, for the autoimmune disorder Systemic Lupus Erythematosus, and highlight the complex considerations required for identifying underlying hormonal and genetic contributions responsible for sex differences in immune responses.

When the balance is broken: X-linked gene dosage from two X chromosomes and female-biased autoimmunity

Women and men exhibit differences in innate and adaptive immunity, and women are more susceptible to numerous autoimmune disorders. Two or more X chromosomes increases the risk for some autoimmune diseases, and increased expression of some X-linked immune genes is frequently observed in female lymphocytes from autoimmune patients. Evidence from mouse models of autoimmunity also supports the idea that increased expression of X-linked genes is a feature of female-biased autoimmunity. Recent studies have begun to elucidate the correlation between abnormal X-chromosome inactivation (XCI), an essential mechanism female somatic cells use to equalize X-linked gene dosage between the sexes, and autoimmunity in lymphocytes. In this review, we highlight research describing overexpression of X-linked immunity-related genes and female-biased autoimmunity in both humans and mouse models, and make connections with our recent work elucidating lymphocyte-specific mechanisms of XCI maintenance that become altered in lupus patients.

Factors That Influence the Immune Response to Vaccination

There is substantial variation between individuals in the immune response to vaccination. In this review, we provide an overview of the plethora of studies that have investigated factors that influence humoral and cellular vaccine responses in humans. These include intrinsic host factors (such as age, sex, genetics, and comorbidities), perinatal factors (such as gestational age, birth weight, feeding method, and maternal factors), and extrinsic factors (such as preexisting immunity, microbiota, infections, and antibiotics). Further, environmental factors (such as geographic location, season, family size, and toxins), behavioral factors (such as smoking, alcohol consumption, exercise, and sleep), and nutritional factors (such as body mass index, micronutrients, and enteropathy) also influence how individuals respond to vaccines. Moreover, vaccine factors (such as vaccine type, product, adjuvant, and dose) and administration factors (schedule, site, route, time of vaccination, and coadministered vaccines and other drugs) are also important. An understanding of all these factors and their impacts in the design of vaccine studies and decisions on vaccination schedules offers ways to improve vaccine immunogenicity and efficacy.

Seroprevalence of antibodies against varicella zoster virus and rubella virus among newly recruited expatriate healthcare workers: a cross-sectional study

OBJECTIVES

To assess the state of immunity to varicella zoster virus (VZV) and rubella virus (RV) among newly recruited healthcare workers (HCWs) in Kuwait before they begin work, and to determine whether there are differences in the prevalence of seronegativity according to nationality, gender, age group and occupation group.

SETTING

This cross-sectional study involved analysis of blood samples from workers newly recruited to the Kuwaiti healthcare system.

PARTICIPANTS

All new non- national HCWs recruited during the study period (n=1540).

INTERVENTION

Enzyme-linked immunoassays for VZV-specific and RV-specific IgG were performed.

RESULTS

Among HCWs, 81.9% and 93.5% were immune to VZV and RV, respectively. Male seronegativity was higher than that of females for both viruses. Regarding VZV, the majority of seronegative individuals were Indians (23.5%), followed by Somalis (12.5), Filipinos (6.5) and Egyptians (5.4%); the between-group differences were significant for all groups. The age groups 20-30 and 30-40 years were most likely to be seronegative, with prevalences of 18.2% and 18.9%, respectively. VZV seronegativity was most common among nurses (21.1%) and least common among physicians (9.2%), and the difference was significant. In addition, RV seronegativity was most frequent among Somalis (12.5%) and lowest among Indians (5.3%); other nationalities (Egyptian, Filipino and others) ranged between 9.1% and 9.6%. Seronegative individuals were most frequently in the younger age group (<20 years old) (17.5%), followed by the >40 years old group (10.4%). RV seronegativity was highest among nurses (6.9%) and lowest among physicians (5.2%).

CONCLUSION

The prevalence of seronegativity is highest among Indians for VZV and Somalis for RV, and HCWs aged 20-40 years for VZV and <20 years for RV. For both viruses, the seronegativity rate was highest for male HCWs, and for nurses compared with other HCWs, with physicians having the lowest prevalence of both viruses.

Dihydrotestosterone levels at birth associate positively with higher proportions of circulating immature/naïve CD5+ B cells in boys

Boys present with higher proportions of immature/naïve CD5⁺ B cells than girls up to 3 years of age. Boys also have higher fractions of regulatory T cells (Tregs) in early infancy, but the mechanisms for these sex-related differences are unknown. In the prospective FARMFLORA follow-up study of 23 boys and 25 girls, we investigated if these immunological differences remained at 8 years of age. We also examined if testosterone or dihydrotestosterone (DHT) levels at birth and at 8 years of age were associated with immune maturation. Immunological variables and androgen levels were examined and measured in blood samples obtained at birth, 3–5 days and at 8 years of age. Boys had higher proportions of CD5⁺ and immature/transitional CD24^hiCD38^hi B cells, whereas girls had higher fractions of B cells with a memory phenotype at 8 years of age. School-aged boys also presented with higher frequencies of Tregs, and a greater capacity to produce T-cell-associated cytokines. Among boys, higher cord blood DHT levels were associated with higher proportions of CD5⁺ B cells in early infancy and at 8 years of life. These results suggest that DHT actions in utero might be involved in the mechanism for delayed peripheral B-cell maturation in boys.

Humoral immunity to mumps in a highly vaccinated population in Taiwan

BACKGROUND

A resurgence of mumps was noted recently and outbreaks were increasingly reported in populations with high vaccine coverage. We aimed to evaluate the seroprevalence to mumps in Taiwan, where a two-dose childhood mumps-containing vaccine program, with a high coverage rate, had been implemented for >20 years.

METHODS

The anti-mumps IgG was determined in 3552 participants of all ages in Taiwan. The age-specific seropositivity rates were calculated and the sociodemographic variables associated with the seronegative sera were analyzed with a logistic regression method.

RESULTS

The overall seroprevalence to mumps was 71%, with a higher rate in adults ≥19 years old than in the pediatric population <19 years old (80.4% versus 62.0%, P < 0.0001). In participants aged 2-20 years, who had been given at least one mumps-containing vaccine, the seropositivity fluctuated across different age subgroups and the lowest rate (36.8%) occurred in the 17-18 years age group. The multivariate analysis identified age within 17-18 years (adjusted odds ratio [aOR] 8.598, 95% confidence interval [CI] 2.990-24.722, P < 0.0001), within 19-20 years (aOR 5.076, 95% CI 1.702-15.133, P = 0.0080), and being a resident of the suburban area of northern Taiwan (aOR 1.089, 95% CI 0.823-1.414, P = 0.0008) as independent factors associated with an increased risk of seronegative sera.

CONCLUSION

The seropositivity to mumps was unexpectedly low in highly vaccinated generations, and with a significant geographical discrepancy in Taiwan, which may have been responsible for the sustained reports of mumps cases in Taiwan.

Prior pregnancy and antenatal rubella sero-negativity-evidence of persistent maternal immunologic alteration?

PROBLEM

It is unclear if the immunologic alterations induced by pregnancy could persist.

METHOD OF STUDY

Antenatal rubella sero-negativity was correlated with gravidity, abortions and parity in 112 083 gravidae managed during 1997-2015, with further analysis stratified for factors known to influence rubella serology.

RESULTS

The 10.2% sero-negative gravidae had different characteristics, and the incidence showed significant difference and positive trend (P<.001 for both) with gravidity, abortions and parity. The pattern remained consistent when analysis was stratified for advanced age, high body mass index and medical history, but was negated by hepatitis B virus infection except for abortions, and by high body mass index for parity. For gravidity 2-4, no difference in rubella sero-negativity was found between gravidae with all previous pregnancies ended in abortion vs delivery.

CONCLUSION

Prior pregnancies diminished rubella immunity in a dose-dependent manner, which may be a reflection of the cumulative effect of pregnancy-associated maternal immunologic alteration.

Impact of antigens, adjuvants and strains on sexually dimorphic antibody response to vaccines in mice

Sexually dimorphic antibody response to vaccines has long been noticed. In addition to sex hormones, other factors such as antigens, adjuvants and strains of mice, as shown by indirect evidence, could also impact the sexual dimorphism. To clarify this, we immunized both gender mice of distinct strains with inactivated FMDV or HBsAg with or without adjuvants, and detected the specific antibody response of the mice. We found that in absence of adjuvants, the recombinant HBsAg but not the inactivated FMDV induced enhanced IgG antibody response in the female BALB/c mice. The o/w emulsion could facilitate the HBsAg to induce the comparable level of IgG antibodies in the male BALB/c mice as that in the females. The o/w emulsion rather than ISA206, a w/o/w emulsion, could assist the inactivated FMDV to induce higher levels of IgM antibodies in the female BALB/c mice. Moreover, the sexually dimorphic antibody response varied among the ICR, BALB/c and the F1 (BALB/c × C57BL/6) mice. Thus the data suggest that antigens, adjuvants and strains all impact the sexually dimorphic antibody response to vaccines and may provide insights for developing gender-based vaccines.

Serological assessment of the establishment of herd immunity against measles in a health district in Malaysia

Background

Malaysia still faces challenges optimizing resources to effectively eliminate measles through high immunization and herd immunity, with sporadic outbreaks of measles as evidence. The objective of this study is to determine the age-specific positive measles antibodies seroprevalence used for assessing the establishment of herd immunity against measles in different age groups. This is useful for identifying vulnerable age groups requiring supplementary immunization.

Methods

A seroprevalence study was conducted among respondents aged 6–9 years, 15–24 years and 45–54 years attending government health clinics in Seremban between September 2014 and January 2015. A total of 1541 measles IgG antibody status were determined using ELISA technique (NovaTec Immundiagnostica GMBH) and assessment of establishment of herd immunity was based on indicators developed by Plans. Data on socio-demographic background as well as medical and medication history were also gathered.

Results

Seropositive rate for all respondents were 87% (95% CI 85–89), while the rest had either indeterminate [6% (95% CI 5–7)] or negative titre [7% (95% CI 6–8)]. None of the factors analyzed except for age were significant predictors of positive measles antibodies. Seropositive rate differed by age with the highest rate seen in adults (94%; CI 92–96), followed by children (90%; 95% CI 87–94) and adolescents, and young adults (74%; 95% CI 70–78). Based on Plans’ indicators, herd immunity was established in adults and children, but not in adolescents and young adults.

Conclusions

To tackle the most susceptible group in the present study, it is advisable to give booster vaccination to secondary school students and freshmen who enter colleges and universities in Malaysia.

Genetically defined race, but not sex, is associated with higher humoral and cellular immune responses to measles vaccination

In addition to host genetic and environmental factors, variations in immune responses to vaccination are influenced by demographic variables, such as race and sex. The influence of genetic race and sex on measles vaccine responses is not well understood, yet important for the development of much-needed improved measles vaccines with lower failure rates. We assessed associations between genetically defined race and sex with measles humoral and cellular immunity after measles vaccination in three independent and geographically distinct cohorts totaling 2872 healthy racially diverse children, older adolescents, and young adults. We found no associations between biological sex and either humoral or cellular immunity to measles vaccine, and no correlation between humoral and cellular immunity in these study subjects. Genetically defined race was, however, significantly associated with both measles vaccine-induced humoral and cellular immune responses, with subjects genetically classified as having African-American ancestry demonstrating significantly higher antibody and cell-mediated immune responses relative to subjects of Caucasian ancestry. This information may be useful in designing novel measles vaccines that are optimally effective across human genetic backgrounds.

Seroprevalence of vaccine-preventable diseases among young children in the United Arab Emirates

OBJECTIVES

In the United Arab Emirates (UAE), many vaccine-preventable diseases are notifiable and are often reported despite high estimated immunization coverage. The serological assessment of immunity against these infections (serosurveillance) complements disease surveillance (notification). This study aimed to assess the yet unmeasured serological immunities to nine vaccine-preventable infections among vaccinated Emirati children.

METHODS

This cross-sectional study involved children who attended the Well-Child Care Programme of the Ambulatory Healthcare Services (Al-Ain, UAE) between July 2014 and September 2015. Serological testing was performed in 227 Emirati children (49% females); subjects were aged (mean±standard deviation) 45±14 months (median 43, range 23-71 months).

RESULTS

The seroprevalence rates varied markedly among the studied vaccine-preventable diseases, ranging from 39.2% (pertussis) to 98.3% (rubella). Other high seroprevalence rates were noted for measles (98.2%) and poliovirus (92%). The seroprevalence rate for mumps was 82.8%, for varicella was 68.3%, for diphtheria was 86.4%, for tetanus was 89.9%, and for Haemophilus influenzae type B was 84.1%.

CONCLUSIONS

A large number of the studied children had low seroprevalence rates against pertussis, varicella, and mumps. Studies are needed to explore whether modifying the national immunization programme could improve these low seroprevalence estimates.

Systematic Review of Measles and Rubella Serology Studies

Serological tests provide information about individual immunity from historical infection or immunization. Cross-sectional serological studies provide data about the age- and sex-specific immunity levels for individuals in the studied population, and these data can provide a point of comparison for the results of transmission models. In the context of developing an integrated model for measles and rubella transmission, we reviewed the existing measles and rubella literature to identify the results of national serological studies that provided cross-sectional estimates of population immunity at the time of data collection. We systematically searched PubMed, the Science Citation Index, and references we identified from relevant articles published in English. We extracted serological data for comparison to transmission model outputs. For rubella, serological studies of women of child-bearing age provide information about the potential risks of infants born with congenital rubella syndrome. Serological studies also document the loss of maternal antibodies, which occurs at different rates for the different viruses and according to the nature of the induced immunity (i.e., infection or vaccine). The serological evidence remains limited for some areas, with studies from developed countries representing a disproportionate part of the evidence. The collection and review of serological evidence can help program managers identify immunity gaps in the population, which may help them better understand the characteristics of individuals within their populations who may participate in transmission and manage risks.

Sex-based differences in immune function and responses to vaccination

Females typically develop higher antibody responses and experience more adverse reactions following vaccination than males. These differences are observed in response to diverse vaccines, including the bacillus Calmette-Guerin vaccine, the measles, mumps and rubella vaccine, the yellow fever virus vaccine and influenza vaccines. Sex differences in the responses to vaccines are observed across diverse age groups, ranging from infants to aged individuals. Biological as well as behavioral differences between the sexes are likely to contribute to differences in the outcome of vaccination between the sexes. Immunological, hormonal, genetic and microbiota differences between males and females may also affect the outcome of vaccination. Identifying ways to reduce adverse reactions in females and increase immune responses in males will be necessary to adequately protect both sexes against infectious diseases.

Rubella susceptibility in pregnant women and results of a postpartum immunization strategy in Catalonia, Spain

BACKGROUND

Elimination of congenital rubella syndrome depends not only on effective childhood immunization but also on the identification and immunization of rubella susceptible women. We assessed rubella susceptibility among pregnant women and evaluated the adherence and response to postpartum immunization with measles, mumps and rubella (MMR) vaccine.

METHODS

Cross-sectional study of women who gave birth at the Hospital Clinic de Barcelona (Spain) between January 2008 and December 2013. Antenatal serological screening for rubella was performed in all women during pregnancy. In rubella-susceptible women, two doses of MMR vaccine were recommended following birth. We evaluated rubella serological response to MMR vaccination in mothers who complied with the recommendations.

RESULTS

A total of 22,681 pregnant women were included in the study. The mean age was 32.3 years (SD 5.6), and 73.6% were primipara. The proportion of immigrants ranged from 43.4% in 2010 to 38.5% in 2012. The proportion of women susceptible to rubella was 5.9% (1328). Susceptibility to rubella declined with increasing maternal age. Immigrant pregnant women were more susceptible to rubella (7.6%) than women born in Spain (4.6%). Multivariate analyses showed that younger age (≤19 years) aOR 1.7 (95% CI 1.1-2.5), primiparas aOR 1.3 (95% CI 1.1-1.5) and immigrant women aOR 1.6 (95% CI 1.4-1.8) were more likely to be susceptible. The second dose of MMR vaccine was received by 57.2% (718/1256) of rubella-susceptible women, with the highest proportion being immigrant women compared with women born in Spain. After vaccination, all women showed rubella immunity.

CONCLUSIONS

The higher rubella susceptibility found in the three youngest age groups and in immigrant women highlights the relevance of antenatal screening, in order to ensure identification and postpartum immunization. The postpartum immunization strategy is an opportunity to protect women of childbearing age and consequently prevent occurrence of CRS, and to increase vaccination coverage against rubella and other vaccine-preventable diseases.

Sex differences in pediatric infectious diseases

The success of the immune response is finely balanced between, on the one hand, the need to engage vigorously with, and clear, certain pathogens; and, on the other, the requirement to minimize immunopathology and autoimmunity. Distinct immune strategies to achieve this balance have evolved in females and males and also in infancy through to adulthood. Sex differences in outcome from a range of infectious diseases can be identified from as early as fetal life, such as in congenital cytomegalovirus infection. The impact of sex hormones on the T-helper 1/T-helper 2 cytokine balance has been proposed to explain the higher severity of most infectious diseases in males. In the minority where greater morbidity and mortality is observed in females, this is hypothesized to arise because of greater immunopathology and/or autoimmunity. However, a number of unexplained exceptions to this rule are described. Studies that have actually measured the sex differences in children in the immune responses to infectious diseases and that would further test these hypotheses, are relatively scarce.

Associations between race, sex and immune response variations to rubella vaccination in two independent cohorts

INTRODUCTION

Immune response variations after vaccination are influenced by host genetic factors and demographic variables, such as race, ethnicity and sex. The latter have not been systematically studied in regard to live rubella vaccine, but are of interest for developing next generation vaccines for diverse populations, for predicting immune responses after vaccination, and for better understanding the variables that impact immune response.

METHODS

We assessed associations between demographic variables, including race, ethnicity and sex, and rubella-specific neutralizing antibody levels and secreted cytokines (IFNγ, IL-6) in two independent cohorts (1994 subjects), using linear and linear mixed models approaches, and genetically defined racial and ethnic categorizations.

RESULTS

Our replicated findings in two independent, large, racially diverse cohorts indicate that individuals of African descent have significantly higher rubella-specific neutralizing antibody levels compared to individuals of European descent and/or Hispanic ethnicity (p<0.001).

CONCLUSION

Our study provides consistent evidence for racial/ethnic differences in humoral immune response following rubella vaccination.

Are healthcare workers immune to rubella?

Healthcare workers (HCW) have high exposure to infectious diseases, some of which, such as rubella, are vaccine-preventable. The aim of this study was to determine the immunity of HCW against rubella. We performed a seroprevalence study using a self-administered survey and obtained blood samples to determine rubella Immunoglobulin G (IgG) antibody levels in HCW during preventive examinations by five Primary Care Basic Prevention Units and six tertiary hospitals in Catalonia. Informed consent was obtained. IgG was determined using an antibody capture microparticle direct chemiluminometric technique. The odss ratio (OR) and 95% confidence intervals (CI) were calculated. Logistic regression was made to calculate adjusted OR. Of 642 HCW who participated (29.9% physician, 38.8% nurses, 13.3% other health workers and 18% non-health workers), 46.6% were primary care workers and 53.4% hospital workers. Of total, 97.2% had rubella antibodies. HCW aged 30-44 years had a higher prevalence of antibodies (98.4%) compared with HCW aged<30 years (adjusted OR 3.92; 95% CI 1.04-14.85). The prevalence was higher in nurses than in other HCW (adjusted OR: 5.57, 95% CI 1.21-25.59). Antibody prevalence did not differ between females and males (97.4% vs. 97.1%, P 0.89), type of center (97.7% vs. 96.8%, P 0.51) or according to history of vaccination (97.3% vs. 96.8%, P 0.82). Seroprevalence of rubella antibodies is high in HCW, but workers aged<30 years have a higher susceptibility (5.5%). Vaccination should be reinforced in HCW in this age group, due to the risk of nosocomial transmission and congenital rubella.

Race and sex-based differences in cytokine immune responses to smallpox vaccine in healthy individuals

We assessed the effects of sex, race and ethnicity on smallpox vaccine-induced immune responses in 1071 armed forces members after primary Dryvax(®) smallpox vaccination, including 790 males and 281 females; 580 Caucasians, 217 African-Americans, and 217 Hispanics. Analysis of vaccinia-specific cytokine responses revealed that Caucasians had higher total IFNγ ELISPOT responses (median 57 spot-forming units/SFUs per 200,000 cells, p=0.01) and CD8(+)IFNγ ELISPOT responses (12 SFUs, p<0.001) than African-Americans (51 and 4 SFUs, respectively) and Hispanics (47 and 8 SFUs, respectively). Similarly, Caucasians secreted higher levels of vaccinia-specific IL-2 (p=0.003) and IFNα (p<0.001) compared to other racial/ethnic groups. Males had higher total IFNγ ELISPOT responses (median 55 SFUs) compared to females (41 SFUs, p<0.001). We observed statistically significant sex-related differences in the secretion of IL-2 (p<0.001), IL-1β (p<0.001) and IL-10 (p=0.017). These data suggest that vaccinia-specific cytokine responses following primary smallpox vaccination are significantly influenced by race and sex of vaccinees.

Prevalence of measles antibodies among health care workers in Catalonia (Spain) in the elimination era

BACKGROUND

Interruption of measles transmission was achieved in Catalonia (Spain) in 2000. Six years later, a measles outbreak occurred between August 2006 and June 2007 with 381 cases, 11 of whom were health care workers (HCW).The objective was to estimate susceptibility to measles in HCW and related demographic and occupational characteristics.

METHODS

A measles seroprevalence study was carried out in 639 HCW from six public tertiary hospitals and five primary healthcare areas. Antibodies were tested using the Vircell Measles ELISA IgG Kit. Data were analyzed according to age, sex, type of HCW, type of centre and vaccination history.The odds ratios (OR) and their 95% CI were calculated to determine the variables associated with antibody prevalence. OR were adjusted using logistic regression.Positive predictive values (PPV) and the 95% confidence intervals (CI) of having two documented doses of a measles containing vaccine (MCV) for the presence of measles antibodies and of reporting a history of measles infection were calculated.

RESULTS

The prevalence of measles antibodies in HCW was 98% (95% CI 96.6-98.9), and was lower in HCW born in 1981 or later, after the introduction of systematic paediatric vaccination (94.4%; 95% CI 86.4-98.5) and higher in HCW born between 1965 and 1980 (99.0%; 95% CI 97.0-99.8). Significant differences were found for HCW born in 1965-1980 with respect to those born in 1981 and after (adjusted OR of 5.67; 95% CI: 1.24-25.91).A total of 187 HCW reported being vaccinated: the proportion of vaccinated HCW decreased with age. Of HCW who reported being vaccinated, vaccination was confirmed by the vaccination card in 49%. Vaccination with 2 doses was documented in only 50 HCW, of whom 48 had measles antibodies. 311 HCW reported a history of measles.The PPV of having received two documented doses of MCV was 96% (95% CI 86.3-99.5) and the PPV of reporting a history of measles was 98.7% (95% CI 96.7-99.6).

CONCLUSIONS

Screening to detect HCW who lack presumptive evidence of immunity and vaccination with two doses of vaccine should be reinforced, especially in young workers, to minimize the risk of contracting measles and infecting the susceptible patients they care for.

Seroprevalence of antibodies against measles, rubella, mumps, varicella-zoster, and B. Pertussis in young adults of Madrid, Spain

In recent years, there has been an increase in the number of cases of certain immunopreventable diseases in our country. A high proportion of these have been recorded among the young adult population. The aim of this study was to determine the seroprevalence of antibodies against immunopreventable diseases with the greatest health impacts on the young adult population (19-39 y of age) in Madrid. We collected a total of 1,153 serum samples from healthy volunteers undergoing routine medical visits and used ELISA to determine the presence of IgG antibodies against measles, rubella, mumps, and varicella zoster, as well as Bordetella pertussis. The Pearson's χ(2) test was used to compare prevalences, the Mann-Whitney U test was used to compare means, and the Kruskal-Wallis test was applied for variables with more than 2 categories. Statistical significance was achieved with p values of<0.05. The global prevalence of antibodies was 92.1% for measles, 94.4% for rubella, 88.3% for mumps, 92.8% for varicella zoster, and 70.2% for B. pertussis. No statistically significant differences were found between genders. The prevalence of antibodies against measles was more than 95% in the group of individuals born after 1986, and the percentage of individuals susceptible to rubella was less than 5% in women born after 1986. In spite of adequate vaccination coverage, in our region, a population of young adults exists who have not achieved the objectives of the WHO for the elimination of measles and congenital rubella syndrome.

Serological survey of mumps immunity among health care workers in the Catalonia region of Spain

Susceptible health care workers are at risk of acquiring and transmitting mumps to or from patients. A survey was carried out in 639 health care workers from tertiary public hospitals and primary care centers in the Catalonia region of Spain during 2009 to determine the prevalence of immunity to mumps among this group. The prevalence of immune health care workers was 87.5% (95% confidence interval, 84.7-89.9). Vaccination with 2 doses of vaccine should be reinforced in health care workers to minimize the risk of mumps transmission in health care settings.

New preventive strategy to eliminate measles, mumps and rubella from Europe based on the serological assessment of herd immunity levels in the population

Herd immunity blocks the transmission of measles, mumps and rubella in a population group when the prevalence of positive serologic results (p) is higher than a critical value (p c), known as the herd immunity threshold. A new preventive strategy should be developed in order to achieve the elimination of measles, rubella and mumps in Europe based on the serological assessment of herd immunity levels in different population groups. This strategy could detect population groups without herd immunity (p < p c) and indicate the additional vaccination coverage required in these groups in order to establish herd immunity and prevent outbreaks. The serological assessment of herd immunity levels in Catalonia, Spain, showed that herd immunity had not been established for measles and mumps in schoolchildren (5-9 years of age) and youths/younger adults (15-29 years of age), and that the additional vaccination coverage required to establish herd immunity in these groups was 1-7%. The new preventive strategy should be used to detect priority population groups for preventive and surveillance activities in European countries.

Results of the rubella elimination program in Catalonia (Spain), 2002-2011

Rubella is usually a mild disease with nonspecific symptoms, but can cause congenital rubella syndrome (CRS) when infection occurs during pregnancy. The objective of this study was to evaluate the sensitivity and positive predictive value of different data sources used for surveillance purposes in the Rubella Elimination Program of Catalonia between 2002 and 2011. The Urgent Notification to the Statutory Disease Reporting System, the Individualized Disease Reporting System, screening for other viruses included in the Measles Elimination Program, the Microbiological Reporting System and the Minimum Hospital Discharge Data were evaluated. 100 suspected cases of postnatal rubella and 6 suspected cases of CRS were detected. For postnatal rubella, Urgent Notification had the highest sensitivity (32.5%; 95%CI 18.6-49.1), followed by the Virus screening in Measles Elimination Program (25%; 95%CI 12.7-41.2). Virus screening in the Measles Elimination Program had the highest PPV (76.9%; 95%CI 46.1-94.9), followed by the Individualized Disease Reporting System (57.1%; 95%CI 28.9-82.3). For CRS cases, the Individualized Disease Reporting System had the highest sensitivity (100%, 95%CI 29.2-100) and the highest PPV (60%; 95%CI 14.7-100). Most confirmed postnatal cases (25 cases, 48.1%) were in the 25-44 y age group followed by the 15-24 y age group (11 cases, 21.2%). The highest values of sensitivity and PPV for the detection of confirmed cases corresponded to activities that were specifically introduced in the measles and rubella elimination programs.

Toxicogenomic profiles in relation to maternal immunotoxic exposure and immune functionality in newborns

A crucial period for the development of the immune system occurs in utero. This results in a high fetal vulnerability to immunotoxic exposure, and indeed, immunotoxic effects have been reported, demonstrating negative effects on immune-related health outcomes and immune functionality. Within the NewGeneris cohort BraMat, a subcohort of the Norwegian Mother and Child Cohort Study (MoBa), immunotoxicity was demonstrated for polychlorinated biphenyls and dioxins, showing associations between estimated maternal intake levels and reduced measles vaccination responses in the offspring at the age of 3. The present study aimed to investigate this link at the transcriptomic level within the same BraMat cohort. To this end, whole-genome gene expression in cord blood was investigated and found to be associated with maternal Food Frequency Questionnaires-derived exposure estimates and with vaccination responses in children at 3 years of age. Because the literature reports gender specificity in the innate, humoral, and cell-mediated responses to viral vaccines, separate analysis for males and females was conducted. Separate gene sets for male and female neonates were identified, comprising genes significantly correlating with both 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and polychlorinated biphenyls (PCB) exposure and with measles vaccination response. Noteworthy, genes correlating negatively with exposure in general show positive correlations with antibody levels and vice versa. For both sexes, these included immune-related genes, suggesting immunosuppressive effects of maternal exposure to TCDD and PCB at the transcriptomic level in neonates in relation to measles vaccination response 3 years later.

Associations between demographic variables and multiple measles-specific innate and cell-mediated immune responses after measles vaccination

Measles remains a public health concern due to a lack of vaccine use and vaccine failure. A better understanding of the factors that influence variations in immune responses, including innate/inflammatory and adaptive cellular immune responses, following measles-mumps-rubella (MMR) vaccination could increase our knowledge of measles vaccine-induced immunity and potentially lead to better vaccines. Measles-specific innate/inflammatory and adaptive cell-mediated immune (CMI) responses were characterized using enzyme-linked immunosorbent assays to quantify the levels of secreted IL-2, IL-6, IL-10, IFN-α, IFN-γ, IFN-λ1, and TNF-α in PBMC cultures following in vitro stimulation with measles virus (MV) in a cohort of 764 school-aged children. IFN-γ ELISPOT assays were performed to ascertain the number of measles-specific IFN-γ-secreting cells. Cytokine responses were then tested for associations with self-declared demographic data, including gender, race, and ethnicity. Females secreted significantly more TNF-α, IL-6, and IFN-α (p<0.001, p<0.002, p<0.04, respectively) compared to males. Caucasians secreted significantly more IFN-λ1, IL-10, IL-2, TNF-α, IL-6, and IFN-α (p<0.001, p<0.001, p<0.001, p<0.003, p<0.01, and p<0.02, respectively) compared to the other racial groups combined. Additionally, Caucasians had a greater number of IFN-γ-secreting cells compared to other racial groups (p<0.001). Ethnicity was not significantly correlated with variations in measles-specific CMI measures. Our data suggest that innate/inflammatory and CMI cytokine responses to measles vaccine vary significantly by gender and race. These data further advance our understanding regarding inter-individual and subgroup variations in immune responses to measles vaccination.

Evaluation of the establishment of herd immunity in the population by means of serological surveys and vaccination coverage

The necessary herd immunity blocking the transmission of an infectious agent in the population is established when the prevalence of protected individuals is higher than a critical value, called the herd immunity threshold. The establishment of herd immunity in the population can be determined using the vaccination coverage and seroepidemiological surveys. The vaccination coverage associated with herd immunity (V(c)) can be determined from the herd immunity threshold and vaccine effectiveness. This method requires a vaccine-specific effectiveness evaluation, and it can be used only for the herd immunity assessment of vaccinated communities in which the infectious agent is not circulating. The prevalence of positive serological results associated with herd immunity can be determined from the herd immunity threshold, in terms of prevalence of antibodies (p(c)) and serological test performance. The herd immunity is established when the prevalence of antibodies is higher than pc. This method can be used to assess the establishment of herd immunity in different population groups, both when the infectious agent is circulating and when it is not possible to assess vaccine effectiveness. The herd immunity assessment in Catalonia, Spain, showed that the additional vaccination coverage required to establish herd immunity was 3-6% for measles, mump and varicella and 11% poliovirus type III in school children, 17-59% for diphtheria in youth and adults and 25-46% for persussis in school children, youth and adults.

[Susceptibility to measles and varicella in healthcare workers in a tertiary hospital in Catalonia]

INTRODUCTION

To estimate the susceptibility to measles and varicella (chickenpox) in healthcare workers in a public tertiary level teaching hospital, in Catalonia.

METHODS

A prevalence study was conducted from January 2006 to December 2008 on 2,752 workers who had serology performed for the determination of measles or varicella by ELISA test during a health examination. Data were analysed by, sex, age, professional category and work unit.

RESULTS

A total of 153 healthcare workers were susceptible to measles and 187 to varicella. The susceptibility of healthcare workers to measles was 6.04% (95% CI: 5.78 to 6.30), and to varicella it was 7.45% (95% CI: 7.14 to 7.75). The highest susceptibility to measles was in resident physicians with 14% (95% CI: 10.8 to 18.5). In high-risk services, where highly immunocompromised patients are attended, the susceptibility of workers was slightly higher than the rest to measles (6.32% vs 5.93%) and varicella (8.34% vs 7.09%). Healthcare workers born after 1980 were 20 times (95% CI: 11.0 to 37.2) more likely to be susceptible to measles, and 2 times (95% CI: 1.2 to 3.2) more likely to be susceptible to varicella than those those born before 1965.

CONCLUSIONS

The susceptibility to measles in healthcare workers in our centre is higher in younger cohorts, with values higher than expected in a community with high vaccination coverage against measles, mumps, rubella vaccine (MMR) in the paediatric population for many years.

[Serological profile of immigrant pregnant women against HIV, HBV, HCV, rubella, Toxoplasma gondii, Treponema pallidum, and Trypanosoma cruzi]

INTRODUCTION

The increase in immigration is changing the prevalence of mother to child infectious diseases. Our aim is to determine the serological profile of foreign pregnant women against these infections.

METHODS

A retrospective cross sectional study was performed in a tertiary hospital from Madrid between August 2007 and October 2008. The seroprevalence against HIV, HBV, HCV, rubeola, T. gondii, T. pallidum and T. cruzi was determined in every pregnant immigrant, as well as in a representative group of Spanish pregnant women.

RESULTS

A total of 2526 immigrant and 157 Spanish pregnant women were studied. None of the Spanish and 0.5% of the foreigners showed antibodies against HIV; 18.9% of them were Sub-Saharan women. Antigen HBs was detected in 2% of the immigrant women and in 1.1% of the Spanish women. Asian women had the highest rate of type B Hepatitis (10.9%). There was 0.9% of type C Hepatitis among the immigrants and 1% among the Spanish. Within the cases with RPR ≥ 1/8, 1.6% were immigrants, most of whom were Latin American. Thirty-one per cent of the immigrants showed antibodies against T. gondii (37.5% from Central America, 2.5% from the Far East). More than 95% of the Spanish women had antibodies against Rubella, this being lower in the rest of the areas (75.5% in Sub-Saharan Africa). T. cruzi infection was detected in 12.1% of the Bolivian women studied.

CONCLUSION

The prevalence of mother-to-child transmitted infections depends on the origin of pregnant women. Knowledge of these differences may lead to improved control these diseases.

Measles antibodies and response to vaccination in children aged less than 14 months: implications for age of vaccination

Passive immunity against measles decreases during the first months of life. The objective of this study was to determine titres of measles antibodies in children aged 9-14 months and their mothers before vaccination, and the children's response to vaccination. Blood samples were collected by capillary puncture before and 28 days after vaccination. Samples were obtained between February and June 2007 during an ongoing measles outbreak. Titres of specific measles IgG antibodies were determined by enzyme-linked immunosorbent assay. Seroconversion was defined as the presence of antibodies after vaccination in subjects without antibodies before vaccination. Maternal antibodies were present in 37·7% of all 69 children included and in 45·1% of children aged 9 months. Of the 51 children in whom a second sample was obtained, 31 (60·8%) were seronegative before vaccination and 61·3% seroconverted. Interference of maternal antibodies was 30%. Advancing the first dose of measles vaccination from 15 to 12 months is a correct strategy, given the increase in the time of susceptibility of infants to measles.

Common SNPs/haplotypes in IL18R1 and IL18 genes are associated with variations in humoral immunity to smallpox vaccination in Caucasians and African Americans

BACKGROUND

Identifying genetic factors that influence poxvirus immunity across races may assist in the development of better vaccines and approaches for vaccine development.

METHODS

We performed an extensive candidate-gene genetic screen (across 32 cytokine and cytokine receptor genes) in a racially diverse cohort of 1056 healthy adults after a single dose of smallpox vaccine. Associations between single-nucleotide polymorphisms (SNPs)/haplotypes and vaccinia virus-specific neutralizing antibodies were assessed using linear regression methodologies.

RESULTS

The combined analysis identified 63 associations between candidate SNPs and antibody levels after smallpox vaccination with P < .05. Thirty-one of these were within the IL18R1 and IL18 genes. Five IL18R1 SNPs, including a coding synonymous polymorphism rs1035130 (Phe251Phe) and 2 promoter SNPs (rs6710885, rs2287037), all in linkage disequilibrium, were associated with significant variations in antibody levels in both Caucasians (P ≤ .016) and African Americans (P ≤ .025). Similarly, associations with 2 intronic IL18 SNPs (rs2043055 and rs5744280) were consistent in the Caucasian (P ≤ .023) and African American samples (P ≤ .014). Haplotype analysis revealed highly significant associations between IL18R1 haplotypes and vaccinia virus-specific antibody levels (P < .001, by combined analysis) that were consistent across races.

CONCLUSIONS

Our study provides evidence for IL18 and IL18R1 genes as plausible genes regulating the humoral immune response to smallpox vaccine in both Caucasians and African Americans.

A large observational study to concurrently assess persistence of measles specific B-cell and T-cell immunity in individuals following two doses of MMR vaccine

The measurement of measles-specific neutralizing antibodies, directed against the surface measles virus hemagglutinin and fusion proteins, is considered the gold standard in measles serology. We assessed functional measles-specific neutralizing antibody levels in a racially diverse cohort of 763 young healthy adolescents after receipt of two doses of measles-mumps-rubella vaccine, by the use of an automated plaque reduction microneutralization (PRMN) assay, and evaluated their relevance to protective antibody levels, as well as their associations with demographic and clinical variables. We also concurrently assessed measles-specific IFNγ Elispot responses and their relation to the observed antibody concentrations. The geometric mean titer for our cohort was 832mIU/mL (95% CIs: 776; 891). Sixty-eight subjects (8.9%) had antibody concentrations of less than the protective threshold of 210mIU/mL (corresponding to PRMN titer of 120; suggesting protection against symptomatic disease), and 177 subjects (23.2%) demonstrated persisting antibody concentrations above 1841mIU/mL (corresponding to PRMN titer of 1052; suggesting total protection against viral infection), 7.4 years after vaccination, in the absence of wild-type virus boosting. The mean measles-specific IFNγ Elispot response for our cohort was 46 (95% CIs: 43; 49) IFNγ-positive spots per 200,000 cells with no relation of cellular immunity measures to the observed antibody concentrations. No significant associations between antibody titers and demographic and clinical variables, including gender and race, were observed in our study. In conclusion, in a large observational study of measles immunity, we used an automated high-throughput measles virus-specific neutralization assay to measure humoral immunity, and concurrently determined measles-specific cellular immunity to aid the assessment of potential susceptibility to measles in vaccinated populations.

Pregnant women in and around dhaka city: are their children at risk of developing congenital rubella syndrome?

Rubella Virus (RUBV) is a common cause of childhood rash and fever in non-immunized populations, and its public health importance relates to teratogenic effects of primary rubella infection in women with early pregnancy. Infection of the fetus may lead to congenital rubella syndrome (CRS). This work aimed to assess the degree of risk associated in acquiring rubella virus infection by the women during pregnancy and developing CRS among their children in Bangladesh. The study population (n = 275) included pregnant mothers (15-38 years) from various socioeconomic backgrounds attending a women health care based hospital. All subjects were personally interviewed, clinically examined and a standardized questionnaire was filled up for each of them. From each participant 3 ml blood was taken and serum was separated. Commercially available ELISA kit was used for the qualitative and quantitative determination of IgM and IgG class antibodies against RUBV in collected serum samples. 209 women were found to contain detectable level of antiRUBV IgG antibodies, but did not possess IgM antibodies against rubella. Only 9% participants were vaccinated previously against rubella virus among the whole antenatal population studied. Ninety-two percent of these vaccinated pregnant women contained serum anti-rubella IgG antibody which was significantly (P = 0.05) higher than that of the nonvaccinated study population (75%). Pregnant women from lower middle and poor socioeconomic class had significantly (P = 0.05) more intra uterine growth retardation (IUGR) of fetus than the upper middle class. 20% of the women of child bearing age examined in this work were not yet exposed to RUBV and at risk of acquiring this virus during pregnancy and subsequently transmitting the virus to the fetus. Our work demonstrates rubella attack rate among antenatal population in Bangladesh as 14.5 in 1000 during pregnancy. A proper and reliable vaccination policy against rubella virus is not yet adopted at the national level in many developing countries including Bangladesh. This work identifies the requirement of detailed study for the identification of intrauterine rubella infection and its related influence on perinatal morbidity and mortality. Thorough epidemiological studies are also considered necessary prior to the development and acceptance of national immunization program against rubella virus in Bangladesh.

The Xs and Y of immune responses to viral vaccines

The biological differences associated with the sex of an individual are a major source of variation, affecting immune responses to vaccination. Compelling clinical data illustrate that men and women differ in their innate, humoral, and cell-mediated responses to viral vaccines. Sex affects the frequency and severity of adverse effects of vaccination, including fever, pain, and inflammation. Pregnancy can also substantially alter immune responses to vaccines. Data from clinical trials and animal models of vaccine efficacy lay the groundwork for future studies aimed at identifying the biological mechanisms that underlie sex-specific responses to vaccines, including genetic and hormonal factors. An understanding and appreciation of the effect of sex and pregnancy on immune responses might change the strategies used by public health officials to start efficient vaccination programmes (optimising the timing and dose of the vaccine so that the maximum number of people are immunised), ensure sufficient levels of immune responses, minimise adverse effects, and allow for more efficient protection of populations that are high priority (eg, pregnant women and individuals with comorbid conditions).

Prevalence of protective measles virus antibody levels in umbilical cord blood samples in Catalonia, Spain

The prevalence of protective antibody levels (>160 mIU/ml) in neonates was 98.5%. The mean measles virus antibody level was 3,406 mIU/ml and increased with maternal age. Measles vaccination was reported by 42% of pregnant women and decreased with age.

Gender effects on humoral immune responses to smallpox vaccine

There are no data currently available on gender and racial variation in smallpox vaccine immune responses. We recruited 1076 healthy adults 18-40 years old who received one dose of the US-licensed smallpox vaccine (Dryvax). Vaccinia neutralizing antibody titers in each subject's serum were determined using a high throughput neutralization assay based on a recombinant, beta-gal expressing vaccinia virus. Results are reported as the serum dilution inhibiting 50% of virus activity (ID(50)). The median ID(50) for all subjects was 132.2 (inter-quartile range (IQR)=78.8, 205.6). While no significant differences were observed with race and ethnicity, females had significantly higher neutralizing antibody titers than males (158.5 [93.2, 255.8] vs. 124.1 [75.2, 185.9]; p<0.0001). As expected, time since vaccination was also associated with variations in neutralizing antibody titers in our subjects. These data indicate that neutralizing antibody titers following primary smallpox vaccination vary by gender.

The influence of public or private paediatric health care on vaccination coverages in children in Catalonia (Spain)

BACKGROUND

Maintaining high vaccination coverages is necessary in order to control vaccine-preventable diseases. We studied vaccination coverages in a representative sample of 630 children aged <3 years in Catalonia in order to determine the relationship between vaccination coverages and socioeconomic factors.

METHODS

Sampling was carried out in a representative sample of the health regions in Catalonia stratified according to habitat. A sample of 630 parents of children aged <3 years born in October 2001 were interviewed by telephone. Information collected included sociodemographic data, type of health care provider (public or private) and information on vaccination coverage for the basic plus booster immunization series (BBI) which consisted of: four DTP, four OPV, one MMR and the doses of Hib and MenC necessary according to age of administration of the first dose.

RESULTS

A total of 87.62% of the children were vaccinated with the BBI series, and no statistically significant differences in coverage between public (87.93%) and private (88.30%) paediatric providers, or between social classes (high: 87.58%, low: 88.81%) were found. Vaccination coverage was associated with attending a day-care centre (OR: 1.89; 95% CI: 1.12-3.21) and maternal university education (OR: 1.84; 95% CI: 1.01-3.33).

CONCLUSION

Vaccination coverages are high and are similar between types of provider, probably due to preventive policies which have made a concerted effort to ensure universal vaccination.

Effectiveness of a vaccination program against mumps in Ukraine

Medical records and incidence data were analyzed retrospectively to document the epidemiology, clinical features, and outcomes of mumps in relation to vaccination status in the Lviv province of Ukraine over a 7.5-year period, beginning in 2000, when a second dose of mumps vaccine was introduced. Lviv, 1 of 27 provinces in western Ukraine, with a land area of 21,833 km(2), had a total population of about 2,555,834 in 2006. The initial success of the second dose introduction in 2000 in Ukraine was limited by a local outbreak of mumps in Lviv province in 2000-2002 due to a vaccine shortage; most cases were over the age of 7 years. The vaccine with the Leningrad-3 virus strain used before 2001 was then replaced by the triple vaccine "Priorix", with the RIT 4385 derivate of the Jeryl Lynn strain, Belgium. Orchitis and aseptic meningitis were associated with the Russian vaccine. Of the 10,894 reported cases, the most severe (367 cases, 3.4%) were hospitalized in the Lviv Hospital for Infectious Diseases. Admitted patients were predominantly male and over 14 years old. Of the 367 patients admitted to the Lviv Hospital for Infectious Diseases, 45.8% had been vaccinated (mostly by a first dose of Russian vaccine), 15.9% had not been vaccinated, and 38.1% had an unknown vaccination status. More mumps cases occurred in winter and spring than in summer and autumn. The clinical picture and complications (orchitis, pancreatitis, meningitis, and encephalitis) were typical of this disease. The vaccine shortage and an increase in the susceptible population among those who received the Russian vaccine contributed to the outbreak. The use of vaccine with a derivate of the Jeryl Lynn strain has resulted in a dramatic drop in mumps cases since 2002.