Prevalence of anti-rubella, anti-measles and anti-mumps IgG antibodies in neonates and pregnant women in Catalonia (Spain) in 2013: susceptibility to measles increased from 2003 to 2013

Serosurveillance for Measles and Rubella

Measles and rubella remain global health threats, despite the availability of safe and effective vaccines. Estimates of population immunity are crucial for achieving elimination goals and assessing the impact of vaccination programs, yet conducting well-designed serosurveys can be challenging, especially in resource-limited settings. In this review, we provide a comprehensive assessment of 130 measles and rubella studies published from January 2014 to January 2024. Methodologies and design aspects of serosurveys varied greatly, including sample size, assay type, and population demographics. Most studies utilized enzyme immunoassays for IgG detection. Sample sizes showed diverse sampling methods but favored convenience sampling despite its limitations. Studies spanned 59 countries, predominantly including adults, and revealed disparities in seroprevalence across demographics, regions, and notably among migrants and women. Age-related declines in antibodies were observed, particularly among infants, and correlations between vaccination status and seropositivity varied. We conclude with an outlook on measles and rubella serosurveillance, emphasizing the need for proper survey design and the advantages of standardized, multiplex serology assays.

Risk Factors for Measles Nonimmunity in Rubella-Immune Pregnant Patients

OBJECTIVE

Measles immunity testing, unlike that for rubella, is not currently part of prenatal screening even though immunity to both is conferred by the measles-mumps-rubella (MMR) vaccine. Although endemic transmission of measles was declared eliminated in the United States in 2001, outbreaks have continued to occur. Given the risks associated with measles infection during pregnancy, we sought to identify risk factors for measles nonimmunity (MNI) in rubella-immune (RI) pregnant individuals.

METHODS

We performed a retrospective observational cross-sectional study of patients receiving prenatal care and delivering at two university hospitals and a county hospital in Southern California from April 1, 2019 to February 1, 2021. Inclusion criteria were pregnant individuals ≥18 years old who had serological testing for rubella and measles during pregnancy. Demographic data were extracted from electronic medical records, including results of serological testing and chronic medical conditions. All subjects were rubella immune, and we compared measles-immune (MI) with MNI groups.

RESULTS

In total, 1,813 RI individuals were identified, with 1,467 (81%) MI and 346 (19%) MNI individuals. Variables associated with an increased risk of MNI included having public health insurance (adjusted relative risk [aRR]: 1.56; 95% confidence interval [CI]: 1.24, 1.97) and Hispanic ethnicity (aRR: 1.37; 95% CI: 1.06, 1.78). Black race was associated with a decreased risk of MNI (aRR: 0.52; 95% CI: 0.29, 0.91). Birth year before 1989 demonstrated a trend toward increased risk of MNI, but this did not reach statistical significance (aRR 1.23; 95% CI: 1.00, 1.52). No differences were seen between the two groups for medical comorbidities.

CONCLUSION

Our study is the first to demonstrate risk factors for measles MNI in patients with documented rubella immunity. In the absence of universal measles serological screening recommendations, the risk factors identified could help guide clinicians in selective screening for those at risk of needing postpartum MMR vaccination.

KEY POINTS

· The rate of measles nonimmunity is higher than previously reported.. · Hispanic ethnicity and use of public insurance are risk factors for measles nonimmunity.. · The current recommendation for history-based screening for measles immunity is likely insufficient..

Screening for TORCH Antibodies in Croatian Childbearing-Aged Women, 2014-2023

TORCH infections usually result in mild maternal morbidity, but may cause severe congenital abnormalities. Therefore, it is important to detect maternal infections, monitor the fetus after the disease has been recognized, and define the seronegative women who are at risk of primary infection during pregnancy. From 2014 to 2023, serum samples from 1032 childbearing-aged and pregnant women (16-45 years) were tested for IgM/IgG antibodies to the most common TORCH pathogens: Toxoplasma gondii, rubella virus (RUBV), cytomegalovirus (CMV), and herpes simplex viruses (HSV-1 and HSV-2). The overall IgG seroprevalence rates were 20.1% for T. gondii, 91.3% for RUBV, 70.5% for CMV, 66.8% for HSV-1, and 3.5% for HSV-2. Only HSV-2 seroprevalence was age-related, with a significant progressive increase in seropositivity from 0% in those aged less than 26 years to 9.3% in those older than 40 years. The seroprevalence of T. gondii was higher in residents of suburban/rural areas than in residents of urban areas (27.4% vs. 17.1%). In addition, participants from continental regions were more often toxoplasma-seropositive than those from coastal regions (22.2% vs. 15.3%). HSV-1 seroprevalence was also higher in suburban/rural areas (71.7% vs. 64.7%). Obstetric history was not associated with TORCH seropositivity. Univariate and multivariate risk analysis showed that suburban/rural areas of residence and continental geographic regions were significant risk factors for T. gondii seroprevalence. Furthermore, suburban/rural area of residence was a significant risk factor for HSV-1 seroprevalence, while older age was a significant risk factor for HSV-2 seroprevalence. A declining trend in the seroprevalence of all TORCH pathogens was observed compared to previous Croatian studies (2005-2011). Similarly, the proportion of women simultaneously IgG-seropositive to two or three pathogens decreased over time. The maternal serology before pregnancy could potentially reduce the burden of congenital TORCH infections.

Seroepidemiology study of rubella virus antibodies among neonates and pregnant women at hospitals in Henan province, China

Rubella virus infection can cause vertical transmission to the fetus during pregnancy. In China's Henan province, rubella surveillance needs to be well-established. In this research, a total of 1933 neonates and 2502 pregnant women were enrolled, and their sera for IgG and IgM antibodies against rubella were tested by chemiluminescence assay. Of 1933 neonates' sera tested, the seropositive of rubella IgG was 68.7%. The seroprevalence of rubella IgM in neonates was 0.4%. 30.9% of neonates had negative results for IgG and IgM antibodies. Two thousand five hundred and two pregnant women participated in the serosurvey, and 79.3% were rubella IgG positive. Rubella IgG seropositivity in pregnant women differed by age and number of births. 0.8% of the pregnant women had positive results for IgM against the rubella virus. The seronegative of rubella IgG and IgM antibodies in pregnant women was 19.8%. Due to the negative rubella-specific IgG antibody, many neonates remain at risk of rubella virus infection. Rubella virus continues to spread since some neonates and pregnant women with rubella-specific IgM antibody positive have been detected. Rubella vaccination may be introduced for childbearing-age women to increase immunity levels against rubella with periodic sero-surveillance.

Serological Responses to Influenza Vaccination during Pregnancy

Pregnant women, newborns, and infants under six months old are at the highest risk of developing severe and even fatal influenza. This risk is compounded by the inability to vaccinate infants under six months, highlighting the importance of vertically transferred immunity. This review identifies novel insights that have emerged from recent studies using animal models of pregnancy and vaccination. We also discuss the knowledge obtained using existing clinical trials that have evaluated influenza-specific serological responses in pregnant women and how these responses may impact early life immunity. We delineate the mechanisms involved in transferring specific maternal antibodies and discuss the consequences for early life immunity. Most importantly, we highlight the need for continued research using pregnant animal models and the inclusion of pregnant women, a commonly neglected population, when evaluating novel vaccine platforms to better serve and treat communicable diseases.

Benefits and Risks of IgG Transplacental Transfer

Maternal passage of immunoglobulin G (IgG) is an important passive mechanism for protecting the infant while the neonatal immune system is still immature and ineffective. IgG is the only antibody class capable of crossing the histological layers of the placenta by attaching to the neonatal Fc receptor expressed at the level of syncytiotrophoblasts, and it offers protection against neonatal infectious pathogens. In pregnant women with autoimmune or alloimmune disorders, or in those requiring certain types of biological therapy, transplacental passage of abnormal antibodies may cause fetal or neonatal harm. In this review, we will discuss the physiological mechanisms and benefits of transplacental transfer of maternal antibodies as well as pathological maternal situations where this system is hijacked, potentially leading to adverse neonatal outcomes.

Strategies for elimination of rubella in pregnancy and of congenital rubella syndrome in high and upper-middle income countries

Rubella infection generally leads to mild symptoms; otherwise, in pregnant women it can cause severe damages. The only way to prevent rubella is vaccine. Before the introduction of the vaccine, up to 4 babies in 1000 live births were born with CRS.

This work aims to review the most important strategies for the elimination of CRS in upper and high-income countries.

Papers were selected through a PubMed search up to January 2019, using keywords rubella, congenital rubella syndrome and epidemiology. Articles published in the last 12 years and referred to upper income and high-income countries in title or abstract were included.

Sixty-five papers were selected dealing with one or more of the following strategies: increasing of rubella vaccination coverage in childbearing age women, males, immigrants; exploitation of all appropriate occasions; improving of rubella surveillance.

Despite numerous suggestions and indications for valid strategies to eliminate rubella in pregnancy and congenital rubella syndrome, a practical application is often missing.

Vertically Transferred Immunity in Neonates: Mothers, Mechanisms and Mediators

Over the last years, an increasing number of outbreaks of vaccine-preventable infectious diseases has been reported. Besides elderly and immunocompromised individuals, newborns and small infants are most susceptible to infections, as their immune system is still immature. This vulnerability during infancy can be mitigated by the transplacental transfer of pathogen-specific antibodies and other mediators of immunity from mother to the fetus during pregnancy, followed postnatally by breast milk-derived immunity. Since this largely antibody-mediated passive immunity can prevent the newborn from infections, neonatal immunity depends strongly on the maternal concentration of respective specific antibodies during pregnancy. If titers are low or wane rapidly after birth, the protection transferred to the child may not be sufficient to prevent disease. Moreover, emerging concepts propose that mothers may transfer active immunity to the newborns via vertical transfer of pathogen-specific T cells. Overall, a promising strategy to augment and prolong neonatal immunity is to vaccinate the mother before or during pregnancy in order to boost maternal antibody concentrations or availability of specific T cells. Hence, a large number of pre-and postconceptional vaccine trials have been carried out to test and confirm this concept. We here highlight novel insights arising from recent research endeavors on the influence of prenatal maternal vaccination against pathogens that can pose a threat for newborns, such as measles, pertussis, rubella and influenza A. We delineate pathways involved in the transfer of specific maternal antibodies. We also discuss the consequences for children's health and long-term immunity resulting from an adjustment of prenatal vaccination regimes.

Seroepidemiological study of rubella in Vojvodina, Serbia: 24 years after the introduction of the MMR vaccine in the national immunization programme

Although rubella is usually a mild childhood disease, this infection in early pregnancy poses a serious problem due to its teratogenic effect. The goal of interrupted circulation and elimination of rubella virus was achieved in many countries in the world. The aim of this study was to determine the status of rubella immunity in Vojvodina and evaluate Serbia's progress toward this goal. A total of 3404 residual serum samples from patients of all ages (1 to 84 years) were included in the study. Samples were collected between May 2015 and December 2017 in Vojvodina. Rubella IgG antibodies were determined using an indirect chemiluminescent immunoassay. Percentage of participants seropositive for rubella antibodies was 92.9% in the entire sample. The highest number of seronegatives was in the youngest (1 year) age group (44.7%), followed by the group aged 24-49 (6.4%) and 2-11 years (6.2%). The absence of a higher percentage of children with protective anti-rubella antibodies in the group aged 2-11 can be explained by a lower immunization coverage during certain years. Participants in the group aged 24-49 were born during the pre-vaccination period with lower rubella incidence, leading to the conclusion that not all individuals of that age came into a contact with the virus. Comparing levels of anti-rubella IgG antibodies of seropositive males and females of different ages reveals that the immunity after a contact with the virus and a previously acquired infection is stronger than the immunity after the vaccination. Although the incidence rate of rubella in Vojvodina has been low for the last ten years, there is still a risk of an outbreak due to a decrease in immunization coverage. This study shows that the percentage of susceptible individuals is high, especially considering women aged 24-49, and that additional ("catch-up") immunization is required.

Measles in pregnant women: A systematic review of clinical outcomes and a meta-analysis of antibodies seroprevalence

OBJECTIVES

Pregnant women represent a category at high risk of severe measles infection, that negatively affects the fetus as well. A systematic review of clinical outcomes of measles infection in gravid subjects and a meta-analysis of antibodies prevalence among pregnant women was conducted.

METHODS

MEDLINE and EMBASE databases were searched up to 18 June 2018. The screening focused on: (i) articles describing the outcome of measles in pregnancy, synthesized in a descriptive fashion; (ii) articles addressing the measles seroprevalence in cohorts of gravid women, analysed quantitatively.

RESULTS

Twenty-nine articles met inclusion criteria. A total of 420 cases of measles in gravid subjects were described, from 1941 to 2012. Among women, 18 deaths (4.3%) occurred, and the most frequent complication was pneumonia (75/420, 17.9%). Prematurity was the most important complication concerning fetal outcomes (55 out of 410 cases with available data, 13.4%). The random-effects pooled seroprevalence of measles in 20,546 gravid women worldwide was 89.3% (95% CI: 87.3-91.1%), that decreased, although not in a statistically significant way, over time (p = 0.54).

CONCLUSIONS

Measles infection in pregnancy is dangerous both for the mother and the foetus. Antibody seroprevalence among gravid women on a global scale is lower than the herd immunity threshold.

Mumps antibodies in the cord blood: Association with maternal recall of mumps. Possible consequences for vaccination strategies

The present study aims to contribute to the evaluation of the serological impact of vaccination against mumps in Portugal, measuring anti-mumps IgG (MuIgG) levels in cord sera and the corresponding proportions of seropositive newborns, and their association with potential predictive variables. The data from this study came from 198 umbilical cord sera. Detailed vaccination records were available for all mothers. MuIgG were measured in the sera, using a commercial immunoassay. The geometric mean concentration (GMC) of MuIgG was 31.7 RU/ml. Seropositive/immune sera (concentration ≥16 RU/ml) were 75.3%. While 49 mothers were "unsure" about ever having had mumps, 46 said they had had the disease and 103 said they had not had it. Eighty eight women did not receive a single dose of MMR while the other received 1 or 2 doses, with different combinations of vaccine strains. This study found that recalling mumps was predictive of higher MuIgG GMC and seropositivity. Maternal age and vaccination status were not associated with GMC or seropositivity. Nevertheless, in the small subset of newborns from vaccinated mothers not recalling mumps, receiving two doses was predictive of higher GMC than just receiving one. Maternal recall of mumps is highly predictive of seropositivity while not recalling the disease results in numerous false-negatives. This is consistent with other studies and with the fact that infection with mumps virus can result in a wide range of clinical manifestations. We agree on the need for further research to support a recommendation of a three (or more)-dose MMR strategy but we also believe that evidence is fast accumulating in favour of a higher dose strategy. The issue of waning immunity due to vaccines when vaccination succeeds in controlling (and nationally eliminating) target diseases like measles and mumps must be urgently taken into account.

Measles in pregnancy: a threat for Italian women?

Measles in pregnancy may lead to serious sequelae for newborns and mothers. In Italy assessment of immunity against measles is not recommended as pregnancy screening. This study aimed to assess the immunity against measles in pregnant women from Apulia Region in Southern Italy between 2016 and 2017. Overall, 96.9% of pregnant women were positive for anti-measles IgG, younger women aged 19–29 years had a seroprevalence below 90%. No samples were positive for anti-measles IgM. In conclusion, younger pregnant women showed to be at higher risk of contracting measles during pregnancy. These findings have implication for measles vaccination policy and highlight the need for measles antibody testing in pregnancy screening in Italy.

Novel Whole-Cell Inactivated Neisseria Gonorrhoeae Microparticles as Vaccine Formulation in Microneedle-Based Transdermal Immunization

Neisseria gonorrhoeae is a strict human pathogen responsible for more than 100 million new sexually transmitted infections worldwide each year. Due to the global emergence of antibiotic resistance, the Center for Disease control (CDC) recently listed N. gonorrhoeae as an urgent threat to public health. No vaccine is available in spite of the huge disease burden and the possibility of untreatable gonorrhea. The aim of this study is to investigate the immunogenicity of a novel whole-cell-based inactivated gonococcal microparticle vaccine formulation loaded in dissolvable microneedles for transdermal administration. The nanotechnology-based vaccine formulation consists of inactivated whole-cell gonococci strain CDC-F62, spray dried and encapsulated into biodegradable cross-linked albumin matrix with sustained slow antigen release. The dry vaccine nanoparticles were then loaded in a dissolvable microneedle skin patch for transdermal delivery. The efficacy of the whole-cell microparticles vaccine formulation loaded in microneedles was assessed in vitro using dendritic cells and macrophages as well as in vivo mouse model. Antibody titers were measured using an enzyme immunosorbent assay (ELISA) and antigen-specific T lymphocytes were assessed in spleens and lymph nodes. Here we report that whole-cell-based gonococcal microparticle vaccine loaded in dissolvable microneedles for transdermal administration induced significant increase in antigen-specific IgG antibody titers and antigen-specific CD4 and CD8 T lymphocytes in mice compared to gonococcal antigens in solution or empty microneedles. Significant increase in antigen-specific IgG antibody levels was observed at the end of week 2 in groups that received the vaccine compared to the group receiving empty nanoparticles. The advantages of using formalin-fixed whole-cell gonococci that all immunogenic epitopes are covered and preserved from degradation. The spherical shaped micro and nanoparticles are biological mimics of gonococci, therefore present to the immune system as invaders but without the ability to suppress adaptive immunity. In conclusion, the transdermal delivery of microparticles vaccine via a microneedle patch was shown to be an effective system for vaccine delivery. The novel gonorrhea nanovaccine is cheap to produce in a stable dry powder and can be delivered in microneedle skin patch obviating the need for needle use or the cold chain.

Seroprevalence of Maternal and Cord Antibodies Specific for Diphtheria, Tetanus, Pertussis, Measles, Mumps and Rubella in Shunyi, Beijing

Maternal antibodies contribute to the protection of young infants from infectious diseases during the early life. However, vaccinations for women of child-bearing age are not routine in China. Therefore, we investigated the level of protective immunity against vaccine preventable diseases in pregnant women and newborns in China. A total of 194 paired maternal and cord blood samples were collected in Beijing from 2016 to 2017. Antibodies specific for the antigens covered by diphtheria-tetanus-pertussis (DTP) and measles-mumps-rubella (MMR) vaccine were determined by ELISA (Euroimmun, Lübeck, Germany). The cut off value of ≥0.1 IU/ml (anti-diphtheria), >0.1 IU/ml (anti-tetanus), >40 IU/ml (anti-pertussis toxin), ≥200 IU/l (anti-measles), ≥45 RU/ml (anti-mumps) and ≥10 IU/ml (anti-rubella) were used to assess the percentage of newborns with protective IgG concentrations, respectively. The results revealed that 61.3%, 73.2%, 97.4%, 30.4%, 65.5% and 17.0% of newborns had no protection against diphtheria, tetanus, pertussis, measles, mumps and rubella. Only 1.0% and 23.7% of newborns had protection against all three components of DTP or MMR, respectively. The finding suggested that most of newborns were susceptible to diphtheria, tetanus, pertussis and mumps, almost one-third of this population had no immune protection against measles, and about one-sixth of them were under threat of rubella infection. These data supported the immunization program for DTP and MMR vaccine in women at child-bearing age.

Voluntary termination of pregnancy: An opportunity for Measles, Mumps and Rubella vaccination in an Italian healthcare local unit

In Italy, the National Plan for the Elimination of Measles and Congenital Rubella 2010-15 suggests offering Measles, Mumps and Rubella (MMR) vaccination to susceptible women who underwent voluntary termination of pregnancy (VTP) In Rome, S. Eugenio Hospital is one of the structures where VTP is practised in an Operative Unit called "Family Planning" The primary goal of this study was to estimate the prevalence of susceptibility to rubella, using IgG and IgM immunoassays, among women accessing VTP and to offering MMR vaccination to susceptible women. Secondarily, this study evaluated acceptance of the vaccination offer From 2013 to 2015, data were collected from 1513 voluntary termination of pregnancy (VTP) cases The results show a significant increase of 5 percent in susceptibility prevalence in the target group from 13.6% in 2013 and 2014 to 18.4% in 2015 The association between rubella susceptibility and age was statistically significant (p<0.01) Throughout the entire period, acceptance of the vaccine proposal was 19% (45/232) among susceptible women; 58% (135/232) refused the vaccine and 23% (52/232) took time to think about it This study shows an increase of 5 percent in the prevalence of rubella susceptibility over two years. This result is worrying, even considering the short span of the data collection The rate of acceptance of vaccination is unsatisfactory considering the possibility of future pregnancies This issue deserves continued action, which, going forward, might transform a "project" into a shared strategy as part of a wider network with the goal of aligning Italy with international recommendations.

Impact of the two-dose rubella vaccination regimen on incidence of rubella seronegativity in gravidae aged 25 years and younger

Objective

This study compared the incidence of rubella seronegativity among gravidae of 25 year-old and younger, between those born in Hong Kong after 1983 when the two-dose rubella vaccination was implemented, versus gravidae born before, to examine the impact of the two-dose regimen.

Methods

In this retrospective cohort study, the incidence of antenatal rubella seronegativity in our parturients managed in1997-2015 was analysed by their age from ≤16 to 25 years, and the effect of year of birth was determined adjusting for confounding factors including teenage status, obstetric history, anthropometric factors, and health parameters including anaemia, thalassaemia trait and hepatitis B carrier status.

Results

Among the 12743 gravidae, the 6103 gravidae born after 1983 had overall higher rubella seronegativity (9.1% versus 4.4%, OR 2.061, 95% CI 1.797–2.364), with significant difference (p = 0.006) and inverse correlation (p<0.001) with age, in contrast to the 6640 gravidae born in/before 1983 whom there was significant difference (p = 0.027) but a positive correlation (p = 0.008) with age. For each year of age, the former had significantly higher incidence of rubella seronegativity except for those of ≤16 years. Regression analysis confirmed that birth after 1983 was independently associated with rubella seronegativity (aOR 2.207, 95% CI 1.902–2.562).

Conclusion

There was a significant trend between rubella seronegativity with age in young gravidae, but the pattern was opposite between gravidae born after versus in/before 1983, with the former having a higher incidence of seronegativity at all ages. Young women covered by the two-dose rubella immunisation programme have a paradoxically higher incidence of rubella seronegativity.

Physicochemical and Preclinical Evaluation of a Novel Buccal Measles Vaccine

The aim of this study is to develop an orally disintegrating film (ODF) containing a microparticulate measles vaccine formulation for buccal delivery. The measles vaccine microparticles were made with biocompatible and biodegradable bovine serum albumin (BSA) and processed by spray drying. These vaccine microparticles were incorporated in the ODF, consisting of Lycoat RS720®, Neosorb P60W® and Tween 80. The yield of the microparticles was approximately 85-95%, w/w. The mean size of the vaccine microparticles was 3.65 ± 1.89 μm and had a slightly negative surface charge of 32.65 ± 2.4 mV. The vaccine particles were nontoxic to normal cells at high concentrations (500 μg/2.5 × 10⁵ cells) of vaccine particles. There was a significant induction of innate immune response by vaccine microparticles which was observed in vitro when compared to blank microparticles (P < 0.05). The vaccine microparticles also significantly increased the antigen presentation and co-stimulatory molecules expression on antigen presenting cells, which is a prerequisite for Th1 and Th2 immune responses. When the ODF vaccine formulation was dosed in juvenile pigs, significantly higher antibody titers were observed after week 2, with a significant increase at week 4 and plateauing through week 6 comparative to naïve predose titers. The results suggest that the ODF measles vaccine formulation is a viable dosage form alternative to noninvasive immunization that may increase patient compliance and commercial distribution.

JC virus infection is acquired very early in life: evidence from a longitudinal serological study

JC virus (JCV) is a widespread member of the Polyomaviridae family. Following primary infection, which occurs asymptomatically during childhood, JCV establishes latency in the host. JCV seroprevalence can reach 80 % in healthy adults, but the age of viral exposure has not been yet characterized. This study was conducted to define JCV seroprevalence in Italian infants and to estimate the date of primary infection. A JCV viral protein 1 (VP1)-GST fusion protein was used in conjunction with a homemade indirect enzyme-linked immunosorbent assay (ELISA) to test for the presence of IgG antibodies to JCV in 981 serum samples collected from 644 Italian infants of different ages (1 day to 3 years old) and in 102 breast milk samples. IgM antibody presence was also evaluated in longitudinally collected samples from 17 selected children. JCV antibody prevalence and normalized optical density (nOD) were calculated. For the longitudinal analysis, generalized estimating equation techniques and spline functions were used to estimate the possible non-linear effects of time on antibody production kinetics. JCV IgG was detected in 71.8 % of the sera. Prevalence increased over time from 46.1 % (1 month old) to 80.7 % (12 months old), 85.9 % (24 months old), and 85.5 % (36 months old). As determined by nOD, the longitudinal analysis of serum IgG amounts in children of this study (ages 1 day to 3 years old) illustrated IgG kinetic changes with statistically significant trends (p = 0.001). One-month-old children were largely negative for JCV IgM (82.4 %), and 58.8 % of children produced JCV IgM within the second and sixth months of life. JCV IgG was detected in 27.3 % of breast milk samples. JCV primary infection likely occurs before 6 months of age, and a sizeable percentage of Italian infants will become JCV seropositive within 2 years of age. This study can be used to determine the optimal age for potential future JCV vaccination in infants.

Measles antibodies in cord blood in Portugal: Possible consequences for the recommended age of vaccination

The optimum age to give the first dose of measles vaccine must balance the risks of disease and vaccine failure. Both are influenced by the levels of transplacentally acquired maternal antibodies. This study was conducted in the Obstetric service of Portuguese hospital, in 2012-2013. Mothers were recruited after informed consent. Measles IgG was measured in 206 cord sera, using a commercial immunoassay. Geometric mean concentrations (and 95% CI) were 1849mIU/ml (1196-2857) and 790mIU/ml (618-1008) in cord sera of newborns from unvaccinated and vaccinated mothers respectively. Maternal age and vaccination status were both associated with the concentration in cord sera, but maternal age was the major predictor. The likely explanation is the same already mentioned in other studies: as a vaccination program progresses, vaccination coverage increases as measles incidence decreases. That results newborns from younger vaccinated mothers having less measles antibodies while the older mothers are more likely to have been infected with the wild virus. As the proportion of vaccinated mothers increase, developed countries tend to anticipate the recommended age of the first dose to 12 months of age. Models using hypothetical measles antibody decay rates in infancy were explored. Anticipating the first dose of MMR1 in Portugal to the age of 12 months might have not been the best decision but results were not conclusive, and arguments supporting or not the anticipation were discussed.