Comparison of immunogenicity and reactogenicity of a measles, mumps and rubella (MMR) vaccine in German children vaccinated at 9-11, 12-14 or 15-17 months of age

A phase II/III randomised, comparative study evaluating the safety and immunogenicity of Biological E's live, attenuated Measles-Rubella vaccine in 9-12 month old healthy infants

Measles is a major cause of childhood mortality and one-third of the world's Measles deaths occur in India. Rubella causes lifelong birth defects (Congenital Rubella Syndrome). Although neither condition has a cure, the MR vaccination can successfully prevent both diseases. The safety of Biological E's live attenuated MR vaccine (BE-MR) was established in 4-5-year-old healthy children. This phase-2/3 study was conducted to assess the safety and immunogenicity of BE-MR in 9-12 month old healthy infants. Overall, 600 subjects were enrolled and equally randomized to receive either BE-MR (n = 300) or the comparator vaccine, SII MR-Vac™ (n = 300). Safety profile of BE-MR vaccine was comparable to SII MR-Vac™ with no severe or serious adverse events (AEs) reported across the study groups. The primary objective of demonstrating non inferiority by BE-MR vaccine compared to SIIL's-MR Vac™ was met. The proportion of subjects with ≥ 2-fold and ≥ 4-fold increase in antibody titre against Measles and Rubella in both the study groups was comparable. Overall, BE-MR vaccine elicited robust and protective immune response as demonstrated by high proportion of sero-protected subjects and a large increase in anti-Measles and anti-Rubella antibodies at day 42 and can be administered safely to infants below one-year of age. This study was prospectively registered with the clinical trial registry of India- CTRI/2016/07/007109.

Cord Blood-Based Approach to Assess Candidate Vaccine Adjuvants Designed for Neonates and Infants

Neonates and infants are particularly susceptible to infections, for which outcomes tend to be severe. Vaccination is a key strategy for preventing infectious diseases, but the protective immunity achieved through vaccination typically is weaker in infants than in healthy adults. One possible explanation for the poor acquisition of vaccine-induced immunity in infants is that their innate immune response, represented by toll-like receptors, is immature. The current system for developing pediatric vaccines relies on the confirmation of their safety and effectiveness in studies involving the use of mature animals or adult humans. However, creating vaccines for neonates and infants requires an understanding of their uniquely immature innate immunity. Here we review current knowledge regarding the innate immune system of neonates and infants and challenges in developing vaccine adjuvants for those children through analyses of cord blood.

Effect of age at vaccination on the measles vaccine effectiveness and immunogenicity: systematic review and meta-analysis

Background

The objectives of this review were to evaluate the effect of age at administration of the first dose of a measles-containing vaccine (MCV1) on protection against measles and on antibody response after one- and two-dose measles vaccinations.

Methods

We conducted a systematic review of the PubMed/MEDLINE, Embase, Web of Science and Cochrane databases (1964–2017) to identify observational studies estimating vaccine effectiveness and/or measles attack rates by age at first vaccination as well as experimental studies comparing seroconversion by age at first vaccination. Random effect models were used to pool measles risk ratios (RR), measles odds ratios (OR) and seroconversion RR of MCV1 administered at < 9, 9–11 or ≥ 15 months compared with 12 or 12–14 months of age.

Results

We included 41 and 67 studies in the measles protection and immunogenicity analyses. Older age at MCV1, from 6 to ≥15 months, improved antibody response and measles protection among one-dose recipients. Pooled measles RR ranged from 3.56 (95%CI: 1.28, 9.88) for MCV1 at < 9 months to 0.48 (95%CI: 0.36, 0.63) for MCV1 at ≥15 months, both compared to 12–14 months. Pooled seroconversion RR ranged from 0.93 (95%CI: 0.90, 0.96) for MCV1 at 9–11 months to 1.03 (95%CI: 1.00, 1.06) for MCV1 at ≥15 months, both compared to 12 months. After a second dose, serological studies reported high seropositivity regardless of age at administration of MCV1 while epidemiological data based on few studies suggested lower protection with earlier age at MCV1.

Conclusions

Earlier age at MCV1 decreases measles protection and immunogenicity after one dose and might still have an impact on vaccine failures after two doses of measles vaccine. While two-dose vaccination coverage is most critical to interrupt measles transmission, older age at first vaccination may be necessary to keep the high level of population immunity needed to maintain it.

Biomaterials for vaccine-based cancer immunotherapy

The development of therapeutic cancer vaccines as a means to generate immune reactivity against tumors has been explored since the early discovery of tumor-specific antigens by Georg Klein in the 1960s. However, challenges including weak immunogenicity, systemic toxicity, and off-target effects of cancer vaccines remain as barriers to their broad clinical translation. Advances in the design and implementation of biomaterials are now enabling enhanced efficacy and reduced toxicity of cancer vaccines by controlling the presentation and release of vaccine components to immune cells and their microenvironment. Here, we discuss the rational design and clinical status of several classes of cancer vaccines (including DNA, mRNA, peptide/protein, and cell-based vaccines) along with novel biomaterial-based delivery technologies that improve their safety and efficacy. Further, strategies for designing new platforms for personalized cancer vaccines are also considered.

Post-immunisation fever and the antibody response to measles-containing vaccines

Fever is a common adverse event following measles vaccination, more frequent among older children and those receiving Measles-Mumps-Rubella-Varicella vaccine vs. Measles-Mumps-Rubella vaccine, two factors associated with a better antibody response. However, the role of fever in the immunogenicity of measles-containing vaccines (MCV) is unclear. We performed a post-hoc pooled analysis of data of 5 216 11 to 22 month-old children receiving MCV from 2004 to 2012 in Europe and USA to evaluate the association between post-immunisation fever and antibody response, measured by geometric mean concentrations (GMCs). We further evaluated fever as an effect modifier or a mediator in the associations between the type of MCV or the age at first vaccination and vaccine immunogenicity. After the first dose, fever was associated with 60% higher GMCs (95% CI 1.51–1.68). For children vaccinated at ⩾12 months, the fever did not modify and minimally mediated (2% to 3%) the association between age and antibody response. Fever mediated 18% of the association between type of MCV and GMCs. In a model including fever, age and type of vaccine, fever was the strongest predictor of GMCs. These results suggest that fever is associated with a stronger measles antibody response independently of age and type of MCV.

Comparisons of the effect of naturally acquired maternal pertussis antibodies and antenatal vaccination induced maternal tetanus antibodies on infant's antibody secreting lymphocyte responses and circulating plasma antibody levels

The goal of this study was to explore the effects of trans-placental tetanus toxoid (TT) and pertussis (PT) antibodies on an infant's response to vaccination in the context of antenatal immunization with tetanus but not with pertussis. 38 mothers received a single dose of TT vaccine during pregnancy. Infants received tetanus and pertussis vaccines at 6, 10 and 14 wk of age. TT and PT anti-IgG secretion by infant lymphocytes was measured at 15 wk. Plasma antibodies were measured at 6 wk (pre-vaccination), 15 wk and 1 y of age. Prior to vaccination, TT and PT antibody were detected in 94.6% and 15.2% of infants. At 15 wk anti-TT-IgG and anti-PT-IgG in plasma was increased by 7-9 fold over pre-vaccination levels, while at 1 y plasma anti-TT-IgG was decreased by approximately 5-fold from the peak and had returned to near the pre-vaccination level. At 1 y plasma anti-PT-IgG was decreased by 2-fold 1 yfrom the 15 wk level. However, 89.5% and 82.3% of infants at 1 y had protective levels of anti-TT and anti-PT IgG, respectively. Pre-vaccination plasma IgG levels were associated with lower vaccine-specific IgG secretion by infant lymphocytes at 15 wk (p < 0.10). This apparent inhibition was seen for anti-TT-IgG at both 15 wk (p < 0.05) and t 1 y (p < 0.10) of age. In summary, we report an apparent inhibitory effect of passively derived maternal antibody on an infants' own antibody response to the same vaccine. However, since the cut-off values for protective titers are low, infants had protective antibody levels throughout infancy.

An increasing, potentially measles-susceptible population over time after vaccination in Korea

BACKGROUND

In Korea, measles occurs mainly in infants <12months of age, who are unvaccinated. In addition, vaccine populations, including adolescents and young adults, can become infected though importation. Thus, the question arises whether the current level of herd immunity in Korea is now insufficient for protecting against measles infection.

METHODS

Age-specific measles seroprevalence was evaluated by performing enzyme immunoassays and plaque reduction-neutralization tests on 3050 subjects aged 0-50years (birth cohort 1964-2014) and 480 subjects aged 2-30years (birth cohort 1984-2012).

RESULTS

The overall seropositivity and measles antibody concentrations were 71.5% and 1366mIU/mL, respectively. Progressive decline in antibody levels and seropositivity were observed over time after vaccination in infants, adolescents, and young adults. The accumulation of potentially susceptible individuals in the population was confirmed by comparing data from 2010 and 2014 seroprevalence surveys. The statistical correlation between measles incidence and measles seronegativity was determined.

CONCLUSIONS

Waning levels of measles antibodies with increasing time post-vaccination suggests that measles susceptibility is potentially increasing in Korea. This trend may be related to limitations of vaccine-induced immunity in the absence of natural boosting by the wild virus, compared to naturally acquired immunity triggered by measles infection. This study provides an important view into the current measles herd immunity in Korea.

Similar Antibody Levels in 3-Year-Old Children Vaccinated Against Measles, Mumps, and Rubella at the Age of 12 Months or 18 Months

BACKGROUND

Measles-mumps-rubella (MMR) vaccinations have been offered to Finnish children at 14-18 months and 6 years of age. In May 2011, the recommended age for the first vaccine dose was lowered to 12 months because of the European measles epidemic.

METHODS

Fingertip capillary blood samples were collected from 3-year-old Finnish children vaccinated once with MMR vaccine at 11-19 months of age. The immunoglobulin G (IgG) antibodies to all 3 MMR antigens were measured with enzyme-linked immunosorbent assay. Neutralizing antibodies and the avidity of antibodies were measured for measles virus.

RESULTS

From April through October 2013, 187 children were enrolled. Equally high proportions of the samples were seropositive for measles virus, mumps virus, or rubella virus antibodies, and there were no significant differences in the IgG antibody concentrations in children vaccinated at 11-13 months of age, compared with those vaccinated at 17-19 months of age. However, among children vaccinated at 11-13 months of age, boys had lower antibody concentrations than girls. Neutralizing measles virus antibody titers were above the threshold for protective immunity in all 78 samples analyzed. The measles virus antibody avidity indexes were high for all children.

CONCLUSIONS

MMR induces similar antibody responses in 12-month-old children as compared to 18-month-old children, but in boys increasing age appears to improve the antibody responses.

Tolerability of Early Measles-Mumps-Rubella Vaccination in Infants Aged 6-14 Months During a Measles Outbreak in The Netherlands in 2013-2014

Background. In 2013–2014, a measles outbreak spread through the Netherlands. To protect young infants, measles-mumps-rubella (MMR) vaccination was offered to those aged 6–14 months in municipalities with routine first-dose MMR vaccine coverage of <90%. We assessed the tolerability of this early administration of MMR vaccine.

Methods. After study entry (n = 1866), parents of eligible infants (n = 10 097) completed a questionnaire (n = 1304). For infants who received an early MMR vaccine dose (n = 962), we asked for information about adverse events (AEs) associated with the dose. AE frequencies were compared between infants aged 6–8, 9–11, and 12–14 months. Using multivariable logistic regression, we assessed the association between the risk of AEs and age at early MMR vaccination.

Results. The response rate was 13%. Parents of 59 infants (6.1%) and 350 infants (36.4%) who received early MMR vaccination reported local and systemic AEs, respectively. Parents of infants vaccinated at 6–8 months of age reported systemic AEs less frequently (32%) than parents of children vaccinated at 9–11 months (45%) and 12–14 months (43%) of age (P = <.001). For local AEs, there were no differences (5%, 7%, and 10%, respectively; P = .08). Compared with vaccination at 6 months, all older infants except those aged 14 months showed an increased risk for any AE and for systemic AEs starting 5–12 days after vaccination.

Conclusions. Early MMR vaccination is well tolerated, with the lowest AE frequencies found in infants aged 6–8 months. It is a safe intervention for protecting young infants against measles.

Zymosan Induces Immune Responses Comparable with Those of Adults in Monocytes, Dendritic Cells, and Monocyte-Derived Dendritic Cells from Cord Blood

OBJECTIVE

To investigate the differences in toll-like receptor (TLR)-mediated immune responses between human neonates and adults, focusing on the cytokine profiles of monocytes, dendritic cells (DCs), and monocyte-derived DCs (MoDCs) in cord and adult blood.

STUDY DESIGN

Purified monocytes, DCs, and MoDCs were stimulated with the following TLR ligands: lipopolysaccharide (TLR4), Pam3CSK4 (TLR1/2), flagellin (TLR5), zymosan (TLR2), polyinosinic:polycytidylic acid (TLR3), imiquimod (TLR7), and CpG (TLR9). Interleukin (IL)-8, IL-6, tumor necrosis factor, IL-1β, and IL-10 concentrations were analyzed in culture supernatants.

RESULTS

Compared with the effects in adult blood, lipopolysaccharide-, Pam3CSK4-, flagellin-, and polyinosinic:polycytidylic acid-stimulated inflammatory cytokine production in cord blood was generally weak in monocytes, comparable in DCs, and elevated in MoDCs. CpG- and imiquimod-stimulated cytokine production in DCs was comparable in cord blood and adult blood, but cytokine production was almost absent in monocytes and MoDCs in both cord blood and adult blood. In contrast, zymosan stimulation produced comparable inflammatory cytokine profiles in the monocytes, DCs, and MoDCs of cord blood and adult blood.

CONCLUSION

The immaturity of TLR-mediated innate immunity in neonates depends on monocytes rather than on DCs. Our results indicate that zymosan-mediated TLR2 signaling may be useful for developing a neonatal vaccine adjuvant.

Assessing mumps outbreak risk in highly vaccinated populations using spatial seroprevalence data

Mumps is a potentially severe viral infection. The incidence of mumps has declined dramatically in high-income countries since the introduction of mumps antigen-containing vaccines. However, recent large outbreaks of mumps in highly vaccinated populations suggest waning of vaccine-induced immunity and primary vaccine failure. In this paper we present a simple method for identifying geographic regions with high outbreak potential, demonstrated using 2006 mumps seroprevalence data from Belgium and Belgian vaccination coverage data. Predictions of the outbreak potential in terms of the effective reproduction number in future years signal an increased risk of new mumps outbreaks. Literature reviews on serological information for both primary vaccine failure and waning immunity provide essential information for our predictions. Tailor-made additional vaccination campaigns would be valuable for decreasing local pockets of susceptibility, thereby reducing the risk of future large-scale mumps outbreaks.

Lower transplacental antibody transport for measles, mumps, rubella and varicella zoster in very preterm infants

BACKGROUND

Maternal antibodies, transported over the placenta during pregnancy, contribute to the protection of infants from infectious diseases during the first months of life. In term infants, this protection does not last until the first recommended measles-mumps-rubella vaccination at 14 months in the Netherlands, while these viruses still circulate. The aim of the study was to investigate the antibody concentration against measles, mumps, rubella and varicella (MMRV) in mothers and preterm infants or healthy term infants at birth.

METHODS

Antibody concentrations specific for MMRV were measured in cord blood samples from preterm (gestational age <32 weeks and/or birth weight <1500 g) and term infants, and matched maternal serum samples, using a fluorescent bead-based multiplex immune-assay.

RESULTS

Due to lower placental transfer ratios of antibodies against MMRV in 96 preterm infants (range 0.75-0.87) compared to 42 term infants (range 1.39-1.65), the preterm infants showed 1.7-2.5 times lower geometric mean concentrations at birth compared to term infants. Maternal antibody concentration is the most important determinant of infant antibody concentration against MMRV.

CONCLUSIONS

Preterm infants benefit to a lesser extent from maternal antibodies against measles, mumps, rubella and varicella than term infants, posing them even earlier at risk for infectious diseases caused by these still circulating viruses.

Childhood vaccination associated adverse events by sex: a literature review

BACKGROUND

Most approved medicines, including vaccines can be associated with adverse events. A vaccine adverse event is defined as any untoward medical occurrence which follows vaccination, but which does not necessarily have a causal relationship with the administration of the vaccine.

METHODS

The objective of this structured literature review is to analyse the adverse events reported with vaccinations usually done during childhood and adolescence: human papilloma virus vaccine, hepatitis B vaccine and measles-mumps-rubella vaccine. We evaluated the vaccine literature on children and adolescents by sex. We searched the Cochrane Database, Medline (Pubmed) and Embase using predefined terms.

RESULTS

Of the 417 publications retrieved from searches in the 3 databases, 89 papers (21%) were identified as potentially relevant to the review. On further scrutiny 41 of these satisfied the criteria for inclusion in the analysis. Serious adverse events related to vaccinations were rare. We found some possible sex related vaccine adverse events. Few trials however reported adverse events by age and sex and very few analyses evaluated the observed differences.

CONCLUSIONS

Despite earlier calls for sex-specific analyses of clinical studies, we found that vaccine trials were rarely reported and published by sex. Prospectively collated vaccine safety data in children and adolescents should be analysed by age and sex, so that clinical trial results can form an evidence base for vaccine practice recommendations.

The relationship between concentration of specific antibody at birth and subsequent response to primary immunization

BACKGROUND AND AIMS

Trans-placentally acquired antibodies can protect infants from infection in the first months of life. However, high concentrations of antibody at birth may impact the infant's own immune response to primary immunization. We examine the relationship between concentration of specific antibody to Bordetella pertussis, Haemophilus influenzae type b (Hib), tetanus toxoid and pneumococcal antigens at birth and following primary immunization.

METHODS

Healthy mother-infant pairs were recruited from a UK maternity unit. Peripheral blood samples were obtained at birth and 4 weeks after primary immunization. Specific antibody concentrations were determined using enzyme-linked immunosorbent assays. Pertussis antibody concentrations >50 IU/ml, Tetanus antibody levels >0.1 IU/ml and Hib antibody levels >0.15 mg/l were regarded as protective.

RESULTS

Following primary immunization, 35/36 (97%) infants had specific antibody concentrations associated with protection against Hib, 32/36 (89%) against pertussis and 36/36 (100%) against tetanus. Concentrations of all specific antibodies were significantly higher than at birth (p<0.0001), except anti-tetanus toxoid, p=0.41. However, there was an inverse correlation between infant antibody concentration at birth and fold-increase in antibody concentration post-immunization for tetanus: rs -0.86 (95%CI -0.93 to -0.74), p<0.0001; pneumococcus: rs -0.82 (95% CI -0.91 to -0.67), p<0.0001; pertussis: rs -0.77 (95% CI -0.89 to -0.58), p<0.0001 and Hib: rs -0.66 (95%CI -0.82 to -0.42), p<0.0001. The highest concentrations of specific IgG at birth were associated with lower concentrations post-immunization for tetanus (p=0.009) and pneumococcus (p=0.03). This association was not observed for Hib (p=0.88) or pertussis (p=0.14).

CONCLUSION

Higher antibody concentration at birth appeared to inhibit the response to infant immunization for tetanus and pneumococcus; the effect was less marked for Hib and pertussis. However, the majority of infants achieved high antibody levels post-immunization. This supports maternal immunization, as high levels of maternally derived antibody at birth may not inhibit infants' immunization responses in a clinically relevant manner.

Spatiotemporal analysis of infant measles using population attributable risk in Shandong province, 1999-2008

BACKGROUND

Reduction of measles incidence and mortality has been encouraging in China. However, it remains an important public health concern among infants. This study aimed to examine the space-time distribution pattern of infant measles occurrence for the period of 1999-2008 in Shandong, China.

METHODS AND FINDINGS

Measles cases among infants aged younger than 1 year were obtained from the national infectious diseases reporting information system. A spatiotemporal analysis using population attributable risk percent (PAR%) was used to distinguish between multiple geographic clusters of potential interest. The analysis detected 29 statistically significant space-time clusters with the most likely cluster in Zaozhuang City from 2006 to 2008. Of the 28 secondary clusters, 22 were found in 2008. The map of PAR%, relative risk (RR) and space-time cluster analysis indicated that the clusters were generally unchanged, and were found south-west and north-west of Shandong. The Lanshan District in Linyi had the highest PAR%, while highest RR was in the Yicheng District in Zaozhuang.

CONCLUSION

There were significant space-time clusters of infant measles in Shandong over the study period. PAR% is an effective way to analyze multiple clusters from their application like RR. Interrupting measles circulation and maintaining routine coverage over 95% may be the only effective strategy to achieve measles elimination.

Outbreak of measles in Central and Eastern Cheshire, UK, October 2008-February 2009

We describe the largest outbreak of measles in Central and Eastern Cheshire (North West England) since the MMR vaccine was introduced in 1988, the majority of cases were not vaccinated and more than 20% of the cases belonged to the travelling community. Over 4 months,147 clinical cases of measles were notified locally to the Cheshire & Merseyside Health Protection Unit (CMHPU). Of these, 67 (45.6%) were laboratory confirmed, 42 (28.6%) were negative, and one was equivocal, leaving 23 probable and 14 possible cases. The primary case was probably an 8-year-old unvaccinated travelling child, symptomatic on 1 October 2008. Measles spread locally and within school-aged children until early February 2009. Most of Central and Eastern Cheshire, including 23 educational institutions (playgroups, nurseries, primary schools, secondary schools, colleges), were affected, showing that there were enough susceptible/unvaccinated children to sustain an outbreak. Nearly a quarter of the confirmed cases (15/67, 22.4%) were aged <13 months and too young to be vaccinated under the UK immunization schedule. This outbreak is a reminder of the importance of achieving herd immunity to prevent spread and protect those at risk of severe illness or complications. There were no fatalities in this outbreak and no significant complications were reported.

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.

Early waning of maternal measles antibodies: why immunization programs should be adapted over time

Primary protection against measles in the first months of life is provided by transferred maternal antibodies. Since the introduction of the measles vaccine, changes in epidemiology have had major effects on the transmission of protective antibodies. The majority of women of childbearing age are now vaccinated and transfer fewer antibodies than naturally immune mothers, conferring shorter protection to their offspring. This article reveals an early loss of maternal antibodies in infants of vaccinated mothers but also in infants of naturally immune women. This increasing susceptibility window between loss of maternal antibodies and vaccination should be taken into account for a timely administration of the first dose of measles vaccine, particularly in the current context of re-emerging measles in Europe. Additional programs are needed to improve vaccination coverage within the global population and to reduce the spread of measles.

Kinetics of maternal antibodies against rubella and varicella in infants

Kinetics of maternal rubella and varicella antibodies in 213 mother-infant pairs are described in a longitudinal study in Belgium. Blood samples are taken at 7 time points (week 36 of pregnancy, birth (cord), 1, 3, 6, 9, and 12 months), and analyzed for anti-rubella IgG and anti-varicella IgG by enzyme linked immunosorbent assay (ELISA). A generalized exponential model is used to analyse maternal antibody decay in infants. Model based, the mean duration of passive immunity is 2.1 months for rubella and 2.4 months for varicella. Infants are susceptible at young age for rubella, a disease with high vaccination coverage, as well as for varicella, an endemic disease in Western Europe.

Modelling the first dose of measles vaccination: the role of maternal immunity, demographic factors, and delivery systems

Measles vaccine efficacy is higher at 12 months than 9 months because of maternal immunity, but delaying vaccination exposes the children most vulnerable to measles mortality to infection. We explored how this trade-off changes as a function of regionally varying epidemiological drivers, e.g. demography, transmission seasonality, and vaccination coverage. High birth rates and low coverage both favour early vaccination, and initiating vaccination at 9-11 months, then switching to 12-14 months can reduce case numbers. Overall however, increasing the age-window of vaccination decreases case numbers relative to vaccinating within a narrow age-window (e.g. 9-11 months). The width of the age-window that minimizes mortality varies as a function of birth rate, vaccination coverage and patterns of access to care. Our results suggest that locally age-targeted strategies, at both national and sub-national scales, tuned to local variation in birth rate, seasonality, and access to care may substantially decrease case numbers and fatalities for routine vaccination.

Antigen-specific lymphocyte proliferation assay and virus neutralization test for measurement of measles-specific immunity in 15-19 years old high school students in Tehran, Iran

Limited information is available concerning the role of measles-specific cell mediated immunity as a correlate of long-term protection from measles infection. Although serological responses are determined in epidemiological studies and high antibody titer is a good indicator of protection, the role of Cell-Mediated Immunity (CMI) has to be defined more clearly. In this study, Lymphocyte Proliferation (LP) and Viral Neutralization Test (VNT) were used in order to measure measles-specific cellular and humoral immune responses of 100 high school students in Tehran. From total number of subjects studied, 33 were girls and 67 were boys and all were in good health. Of these, 77 had protective neutralizing measles antibody titers and 23 did not have such titer. The results of LP showed that 89 subjects had protective cellular immune responses and 11 did not. A quantitative relationship between humoral and cellular immune responses was not observed. These findings suggest that measles-specific protective CMI is measurable for longer time in comparison to humoral immunity. These data suggest that LP responses may be better sustained than antibody titers in some children.

Passive transmission and persistence of naturally acquired or vaccine-induced maternal antibodies against measles in newborns

This paper reviews literature on passively transferred maternal antibodies against measles in infants. The amount and decay of these antibodies can be a result of changing patterns in society: increasing cohorts of women are vaccinated against measles instead of having naturally acquired immunity, the age of first childbirth is increasing and young adults are less exposed to natural boosters. The concentration and persistence of maternal antibodies differ in infants of women vaccinated against measles versus infants of naturally immune women. The date for commencing universal measles vaccination should take into account the presence of these antibodies since they can hamper the immunological response to vaccination. Each country should therefore consider adapting the timing of vaccination in relation to its measles sero-epidemiological situation. The possibility of priming the immune system with an early vaccine dose and boosting later on offers opportunities for vaccination at very young age.

Ribonucleotides: conditionally essential nutrients shown to enhance immune function and reduce diarrheal disease in infants

It remains a goal of pediatric nutrition to provide optimal nourishment for infants who are not fed human milk. Investigators have attempted to emulate the composition and functionality of human milk, the gold standard for infant nutrition. These efforts began with the analysis of milk components and continued with assessments of biological effects that culminated in clinical studies in infants. This chapter summarizes the path that researchers followed to study ribonucleotides and their role in infant nutrition. Based on analytical methods for the quantification of ribonucleotides in human milk, investigators assessed their potential impact on the immune systems of infants and looked for concomitant mechanistic explanations. These inquiries evolved into clinical trials in which ribonucleotide-supplemented formula performance was compared with that of non-supplemented formulas and with human milk. This chapter intends to summarize an area of pediatric nutrition that has yielded both enlightening evidence and seemingly contradictory data.

Differential immune responses to primary measles-mumps-rubella vaccination in Israeli children

Measles remains an important cause of morbidity and mortality worldwide, primarily due to problems associated with delivery of the live attenuated vaccine to susceptible populations. In some developed countries, there is concern about the effects of immunization on the immune system. In this study, we analyzed the responses of 12-month-old Bedouin and Jewish children living in Israel to routine measles-mumps-rubella (MMR) vaccination. Seroconversion to measles was 99% in Bedouin and 79% in Jewish children (P < 0.01), and that to mumps and rubella was 92 to 100% in both groups. Measles neutralizing antibody titers were higher in Bedouin (333 +/- 39 mIU/ml) than Jewish (122 +/- 60 mIU/ml) children (P < 0.002). Immunoglobulin G levels were higher in Bedouin than Jewish children (P = 0.007) and increased after vaccination (P = 0.0009). Leukocyte (P < 0.02) and lymphocyte (P = 0.04) counts were higher and CD4 lymphocyte percentages were lower (P < 0.001) in Bedouin than Jewish children before and after vaccination. Leukocyte counts and natural killer cell numbers did not change after vaccination, but lytic activity increased in Bedouin children (P < 0.005). Spontaneous proliferation of cultured peripheral blood mononuclear cells increased with vaccination, but there were no changes in the proliferative responses to phytohemagglutinin or tetanus toxoid. In summary, no adverse effects of MMR vaccination on immune function were detected. However, there were differences in underlying immunologic parameters and in response to the measles component of the vaccine between Bedouin and Jewish children. It is not known whether genetic differences or environmental exposure accounts for these differences.

Transplacentally acquired immunoglobulin G antibodies against measles, mumps, rubella and varicella-zoster virus in preterm and full term newborns

IgG antibody values against measles, mumps, rubella and varicella-zoster virus in 71 full term and 101 preterm infants and their 152 mothers and the decay of maternally acquired antibodies during infancy were studied. Both magnitude of transplacental antibody passage and cord blood antibody values correlated with gestational age. After 6 months preterm infants born before 32 weeks of gestation had lost maternal antibodies.

The Brighton Collaboration: addressing the need for standardized case definitions of adverse events following immunization (AEFI)

To further scientific progress of immunization safety, comparability of data from clinical trials and surveillance systems is essential. Comparability requires the availability of standardized case definitions for adverse events following immunization (AEFI) and guidelines for case determination, recording and data presentation.

METHOD

International collaborative working groups, consisting of professional volunteers from developed and developing countries, conduct systematic literature reviews to develop 50-100 AEFI definitions. Case definitions are finalized after a comment period by a reference group consisting of organizations concerned with immunization safety, and will be disseminated via the world-wide-web and other means for free world-wide use.

RESULTS

Literature reviews yielded substantial diversity in data collection and presentation. We have developed standardized case definitions together with guidelines for use in clinical trials and surveillance systems.

CONCLUSIONS

Diversity in safety methods leads to considerable loss of scientific information. We have built the necessary international network of currently about 300 participants from patient care, public health, scientific, pharmaceutical, regulatory and professional organizations to develop and assess standardized AEFI case definitions and guidelines. Evaluation studies, global implementation, ongoing definition development and a continuously growing network will be essential for the success of the collaboration.

Neonatal and early life vaccinology

Preclinical and human vaccine studies indicate that, although neonatal immunisation does not generally lead to rapid and strong antibody responses, it may result in an efficient immunological priming, which can serve as an excellent basis for future responses. The apparent impairment of CD4 and CD8 T-cell function in early life seems to result from suboptimal antigen-presenting cells-T cell interactions, which can be overcome by use of specific adjuvants or delivery systems. Although persistence of maternal antibodies may limit infant antibody responses, induction of T-cell responses largely remain unaffected by these passively transferred antibodies. Thus, neonatal priming and early boosting with vaccine formulations optimised for sufficient early life immunogenicity and maximal safety profiles, could allow better control of the huge infectious disease burden in early life.