Active immunization of premature and low birth-weight infants: a review of immunogenicity, efficacy, and tolerability

Delayed Start of Routine Vaccination in Preterm and Small-for-Gestational-Age Infants: An Area-Based Cohort Study from the Tuscany Region, Italy

Preterm and small-for-gestational-age (SGA) infants are more susceptible to vaccine-preventable diseases. To evaluate routine vaccination timeliness in these high-risk groups, a full birth cohort of infants (n = 41,502) born in 2017 and 2018 in Tuscany was retrospectively followed up until 24 months of age. Infants were classified by gestational age (GA) and SGA status. The vaccinations included: hexavalent (HEXA), measles-mumps-rubella, varicella, pneumococcal conjugate (PCV), and meningococcal C conjugate. Time-to-event (Kaplan–Meier) analyses were conducted to evaluate the timing of vaccination according to GA; logistic models were performed to evaluate the associations between GA and SGA with vaccination timeliness. Time-to-event analyses show that the rate of delayed vaccine receipt increased with decreasing GA for all the vaccinations, with a less marked gradient in later vaccine doses. Compared to full-term infants, very preterm infants significantly showed an increased odds ratio (OR) for delayed vaccination in all the vaccinations, while moderate/late preterm infants only showed an increased OR for HEXA-1, HEXA-3, PCV-1, and PCV-3. SGA infants had a significantly higher risk of delayed vaccination only for HEXA-1 and PCV-1 compared to non-SGA infants. In conclusion, vaccinations among preterm and SGA infants showed considerable delay. Tailored public health programs to improve vaccination timeliness are required in these high-risk groups.

Health facility readiness to care for high risk newborn babies for early childhood development in eastern Uganda

BACKGROUND

The neonatal mortality rate in Uganda has barely changed over the past decades, estimated at 28/1000 and 27/1000 live births in 2006 and 2016 respectively. The survivors have a higher risk of developing neurodevelopmental disabilities (NDD) due to brain insults from perinatal complications related to poor quality of health services during pregnancy, around the time of birth, and during the postnatal period. This study aimed to assess health facility readiness to care for high risk newborn babies in order to inform programming that fosters early childhood development in eastern Uganda.

METHODS

A cross sectional study of 6 hospitals and 10 higher level health centers that offer comprehensive maternal and newborn care was carried out in February 2020 in eastern Uganda. A World Health Organization Service Availability and Readiness Assessment tool (SARA) was adapted and used to assess the health facility readiness to manage maternal and neonatal conditions that are related to NDD. In addition, 201 mothers of high risk newborn babies were interviewed on their satisfaction with health services received. Readiness scores were derived from percentage average facilities with available infrastructure and essential medical commodities to manage neonatal complications. Descriptive statistics were computed for client satisfaction with service provision, and p values used to compare private not for profit to public health facilities.

RESULTS

There was limited availability in numbers and skilled human resource especially the neonatal nurses. Hospitals and health centers scored least in preterm and hypothermia care, with averages of 38% and 18% respectively. The highest scores were in essential newborn care, with readiness of 78% and 85% for hospitals and health centers, followed by resuscitation at 78% and 77%, respectively. There were no guidelines on positive interaction with newborn babies to foster neurodevelopment. The main cause of admission to neonatal care units was birth asphyxia followed by prematurity, indicative of intrapartum care challenges. The overall client satisfaction with health services was higher in private not for profit facilities at 91% compared to public hospitals at 73%, p = 0.017.

CONCLUSION

Health facility readiness was inadequate in management of preterm complications. Efforts should, therefore, be geared to improving availability of inputs and quality of emergency obstetric and newborn care in order to manage high risk newborns and reduce the burden of NDD in this setting.

Hepatitis B Birth Dose Vaccination among Vietnamese Children: Implications for the Expanded Program on Immunization

Background

This study assesses the prevalence of Vietnamese children receiving the hepatitis B (HepB) vaccine birth dose and explores its associated socioeconomic factors.

Methods

We used the data of the Multiple Indicator Cluster Survey, 2014. We estimated the overall percentage of HepB birth dose vaccination among 0–23-month-old children and its percentages according to selected characteristics. Multiple logistic regression was applied.

Results

62.8% of children received the HepB vaccine birth dose. The prevalence rates by selected factors ranged from 35.3% to 76.7%. The categories with the lowest prevalence rates were children who had low birth weight (41.6%), had a mother aged less than 20 years (35.3%), had a mother with primary or less education (42.7%), belonged to ethnic minorities (30.3%), resided in rural areas (59.9%), and were in the 1^st quintile of mother's socioeconomic status (38.6%). Receiving HepB vaccine birth dose was associated with child's birth weight, mother's age, mother's education, socioeconomic status, and ethnicity.

Conclusions

This study identified vulnerable groups, upon which policy-makers should focus their efforts to equitably and sustainably tackle birth dose HepB vaccine coverage as well as the full vaccination coverage, thereby promoting long-lasting herd immunity in this country.

Vitamin A Supplementation during Pregnancy Enhances Pandemic H1N1 Vaccine Response in Mothers, but Enhancement of Transplacental Antibody Transfer May Depend on When Mothers Are Vaccinated during Pregnancy

Background

In the growing embryo, the vitamin A requirement is tightly regulated. Maternal vitamin A deficiency during pregnancy may alter maternal immune function to accommodate the fetus.

Objective

Our primary objective was to determine the effect of oral vitamin A supplementation (VAS) during pregnancy and until 6 mo postpartum on pandemic H1N1-vaccine responses in mothers and their infants at 6 mo of age.

Methods

In this randomized controlled clinical trial, pregnant women (n = 112) during the second trimester (mean ± SD: 14 ± 1 wk) were assigned to receive either an oral dose of 10,000 IU vitamin A or placebo weekly until 6 mo postpartum. During the third trimester, mothers received a single dose of inactivated pandemic H1N1-influenza vaccine. Hemagglutination-inhibition (HAI) titer was measured in cord, infant, and maternal blood samples. Multivariate regressions with adjustments were used for data analysis.

Results

Seventy-six percent of women had low plasma retinol concentrations (<1.05 μmol/L) in their second trimester. VAS of mothers increased vitamin A concentrations in cord blood by 21.4% and in colostrum by 40.7%. At 6 mo postpartum, women in the vitamin A group had 38.7% higher HAI titers and a higher proportion of HAI titer of ≥1:40 of the cutoff compared with the placebo group. A total of 54.5% of infants had an HAI titer ≥1:40 at 6 mo of age, but there was no difference in HAI titer in infants between groups. Overall, HAI in cord blood did not differ between groups, but in the placebo group, cord blood HAI was negatively associated with maternal "vaccination-to-delivery intervals" (rs = -0.401; P = 0.5), and maternal VAS increased cord blood HAI 6-fold if antenatal immunization was administered ≥10 wk before delivery.

Conclusions

In a community with low vitamin A status, weekly maternal VAS during pregnancy and postpartum increases the breast-milk vitamin A concentration and enhances prenatal H1N1-vaccine responses in mothers, but the benefits of maternal VAS in transplacental antibody transfer may depend on the time of gestation when mothers were vaccinated. This trial was registered at clinicaltrials.gov as NCT00817661.

Immunization Completion in Infants Born at Low Birth Weight

BACKGROUND

Low birth weight (LBW) has been associated with underimmunization. We sought to understand the effect of LBW on immunization completion after controlling for previously hypothesized mediators, including prematurity, neonatal illness, well-child care, non-well-child visits, and provider consistency.

METHODS

We formed a retrospective cohort of infants born between 2008 and 2011 with ≥2 years of military healthcare follow-up. International Classification of Diseases, Ninth Revision codes were used to identify LBW, preterm birth, neonatal illnesses, well-child visits, non-well-child visits, provider consistency, and parental rank in the inpatient and outpatient records. Immunization records were extracted from both records. Logistic regression determined the odds of immunization completion and well-child care completion (ie, having had ≥6 WCC visits by 15 months of age).

RESULTS

Of 135964 included infants, 116521 (85.7%) were completely immunized at the age of 2 years. In adjusted analysis, the odds of immunization completion were significantly decreased in infants born at LBW (odds ratio [OR], 0.88 [95% confidence interval (CI), 0.79-0.97]), very LBW (OR, 0.61 [95% CI, 0.48-0.77]), or extremely LBW (OR, 0.45 [95% CI, 0.33-0.63]) or at ≤32 weeks' gestation (OR, 0.76 [95% CI, 0.63-0.92]), infants with chronic lung disease (OR, 0.63 [95% CI, 0.45-0.88]), male infants (OR, 0.96 [95% CI, 0.93-0.99]), and infants who experienced decreased provider consistency (OR, 0.92 [95% CI, 0.91-0.92]). The rate of immunization completion increased with the overall number of healthcare visits (OR, 1.02 [95% CI, 1.02-1.02]) and complete well-child care (OR, 1.80 [95% CI, 1.75-1.86]). However, children born LBW or preterm were significantly less likely to have complete well-child care.

CONCLUSIONS

After adjustment for preterm birth, comorbid neonatal conditions, and early childhood patterns of healthcare use, LBW was significantly associated with immunization noncompletion in a universal healthcare system. Provider consistency and well-child care seem important for increasing immunization completion in LBW infants.

Adjuvant Effect of Bacille Calmette-Guérin on Hepatitis B Vaccine Immunogenicity in the Preterm and Term Newborn

Immunization is key to protecting term and preterm infants from a heightened risk of infection. However, preterm immunity is distinct from that of the term, limiting its ability to effectively respond to vaccines routinely given at birth, such as hepatitis B vaccine (HBV). As part of the Expanded Program on Immunization, HBV is often given together with the live-attenuated vaccine Bacille Calmette-Guérin (BCG), known to activate multiple pattern-recognition receptors. Of note, some clinical studies suggest BCG can enhance efficacy of other vaccines in term newborns. However, little is known about whether BCG can shape Th-polarizing cytokine responses to HBV nor the age-dependency of such effects, including whether they may extend to the preterm. To characterize the effects of BCG on HBV immunogenicity, we studied individual and combined administration of these vaccines to cord newborn and adult human whole blood and mononuclear cells in vitro and to neonatal and adult mice in vivo. Compared to either BCG or HBV alone, (BCG + HBV) synergistically enhanced in vitro whole blood production of IL-1β, while (BCG + HBV) also promoted production of several cytokines/chemokines in all age groups, age-specific enhancement included IL-12p70 in the preterm and GM-CSF in the preterm and term. In human mononuclear cells, (BCG + HBV) enhanced mRNA expression of several genes including CSF2, which contributed to clustering of genes by vaccine treatment via principle component analysis. To assess the impact of BCG on HBV immunization, mice of three different age groups were immunized subcutaneously with, BCG, HBV, (BCG + HBV) into the same site; or BCG and HBV injected into separate sites. Whether injected into a separate site or at the same site, co-administration of BCG with HBV significantly enhanced anti-HBV IgG titers in mice immunized on day of life-0 or -7, respectively, but not in adult mice. In summary, our data demonstrate that innate and adaptive vaccine responses of preterm and term newborns are immunologically distinct. Furthermore, BCG or "BCG-like" adjuvants should be further studied as a promising adjuvantation approach to enhance immunogenicity of vaccines to protect these vulnerable populations.

Subcutaneous diphtheria and tetanus vaccines in children with haemophilia: A pilot study and review of the literature

INTRODUCTION

Subcutaneous (SQ) vaccination has emerged as standard of care in children with severe bleeding disorders to reduce unnecessary factor exposure and avoid provoking an intramuscular bleed, but little is known about comparative immunogenicity to intramuscular (IM) vaccination.

AIM

To confirm immunogenicity of Diphtheria Tetanus acellular Pertussis (DTaP) vaccines administered SQ to individuals <6 years old with haemophilia.

METHODS

We performed a retrospective and prospective pilot study of tetanus and diphtheria antibody titres among patients evaluated at our Haemophilia Treatment Centre between 2015-2016. Children with haemophilia who had received three to four doses of DTaP containing vaccine administered SQ were eligible.

RESULTS

Eight children met inclusion criteria. The mean age at the time of diphtheria and tetanus antibody testing was 21.1±17.8 months. All children who received SQ diphtheria and tetanus developed a positive antibody titre to both antigens. There was no statistically significant difference in distribution of titre values. The average time between the last dose of vaccine and antibody testing was 6.6±3.9 months among SQ vaccinated subjects. Minor injection site reactions were common with SQ vaccines.

CONCLUSION

SQ administration of diphtheria and tetanus vaccination appears to be immunogenic in a pilot study of Haemophilia patients and supports this practice as the standard of care for this population.

Vaccination timeliness in preterm infants: An integrative review of the literature

AIMS AND OBJECTIVES

To take a systematic approach to reviewing the scientific literature examining the timeliness of vaccination in preterm infants and to identify any factors associated with timeliness.

BACKGROUND

Preterm infants are vulnerable to infection and guidance advocates they are vaccinated in accordance with their full-term peers. Vaccination is well tolerated and protective immune responses are observed, yet some early enquiries suggest that preterm infants experience unwarranted delays. The recent surge in pertussis cases and the increase in vaccinations administered make this a topic requiring further exploration.

DESIGN

An integrative review of the empirical literature.

METHODS

Studies were identified following a search of Medline, Academic Search Premier, Cochrane Database of Systematic Reviews and the Cumulative Index to Nursing and Allied Health Literature. The review methods used were influenced by a narrative synthesis approach. The retrieval of papers adhered to recognised reporting standards.

RESULTS

Fourteen studies were identified, which indicated that infants with the lowest gestational ages and birthweights experience the greatest delays. Vaccination timeliness is influenced by hospitalisation and increased postdischarge follow-up. There was a lack of consensus to indicate that parental socio-economic status and level of education were indicators for a delay. The studies propose that many delays are unjustified and not according to genuine contraindications.

CONCLUSION

This review indicates that preterm infants are not vaccinated in a timely manner. Those involved in vaccinating preterm infants must be informed of the genuine contraindications to avoid unnecessary delays putting preterm infants at an increased risk of infection.

RELEVANCE TO CLINICAL PRACTICE

Care providers should acknowledge the risk of a delay in preterm infants and actively promote vaccination in this population. Regular training should help to negate the occurrence of inappropriate delays, and careful discharge planning is needed to ensure that preterm infants are vaccinated on time.

Quality Improvement Project to Reduce Delayed Vaccinations in Preterm Infants

BACKGROUND

Preterm infants are especially vulnerable to infectious diseases. Although vaccinations are a safe and effective measure to protect preterm infants from vaccine-preventable diseases, delays in vaccinations are not uncommon.

PURPOSE

The goal of this quality improvement project was to improve on time vaccinations of preterm infants hospitalized in the neonatal intensive care unit.

METHODS

The Plan-Do-Study-Act model of quality improvement was adopted to develop, test, and implement interventions aimed at improving timely vaccination of preterm infants. The primary outcome measure of interest was the rate of on time vaccination, which was defined as the proportion of medically eligible preterm infants who received vaccinations within 2 weeks of the recommended schedule.

RESULTS

Baseline on time vaccination rate was only 36%. Following several Plan-Do-Study-Act cycles, a steady increase in on time vaccinations of eligible infants was observed, and a new baseline on time vaccination rate of 82% was achieved.

IMPLICATIONS FOR PRACTICE

Simple interventions implemented within the context of Plan-Do-Study-Act cycles are effective in improving timely vaccinations among preterm infants.

IMPLICATIONS FOR RESEARCH

Future research that focuses on vaccinations in preterm infants is needed to further reinforce the safety and efficacy of vaccines. Effective methods on how to disseminate and apply this knowledge to practice should also be studied.Video Abstract available at http://links.lww.com/ANC/A27.

Respiratory Decompensation and Immunization of Preterm Infants

BACKGROUND

Concern for respiratory decompensation after immunization in premature infants, particularly those with bronchopulmonary dysplasia (BPD), may lead to delayed and altered immunization schedules.

METHODS

A retrospective cohort of premature infants at <32 weeks' gestational age cared for in a tertiary level 4 NICU and immunized during their hospital stay were evaluated for respiratory decompensation within 72 hours of immunization. Respiratory measurements including change in respiratory support, mean fraction of inspired oxygen, and apnea, bradycardia, and desaturation events were compared between those infants with BPD and those without. The primary outcome was the difference in respiratory decompensation defined as a composite of increased respiratory support or increased fraction of inspired oxygen ≥10% within 72 hours of immunization.

RESULTS

Of 403 infants admitted to the NICU and immunized, 240 met the study criteria. Of those infants, 172 had a diagnosis of BPD. There was no difference in the primary outcome of respiratory decompensation after immunization between groups (P = .65). There was also no significant difference in apnea, bradycardia, and desaturation events between groups (P = .51).

CONCLUSIONS

In this cohort, respiratory decompensation requiring clinical intervention after immunization of preterm infants both with and without BPD was uncommon and not significantly different between groups. Consideration for immunization of this vulnerable population should not be delayed out of concern for clinical deterioration.

Response on Pneumococcal Vaccine in Preterm Infants After Neutral and Acidic Oligosaccharides Supplementation

BACKGROUND

Supplementation of oligosaccharides in premature infants was shown to influence the immune system. We determined the effect of combined short-chain galacto-oligosaccharides (scGOS), long-chain fructo-oligosaccharides (lcFOS) and pectin-derived acidic oligosaccharides (pAOS) on antibody concentrations after pneumococcal conjugate vaccination in very preterm infants.

METHODS

Very preterm infants with gestational age <32 weeks and/or birth weight <1500 g were randomized to receive enteral supplementation with scGOS/lcFOS/pAOS or placebo between days 3 and 30 of life. Blood samples were collected at birth, 5 and 12 months of age and compared with term samples from a Dutch cross-sectional population-based serosurveillance study. IgG antibody levels to pneumococcal capsular polysaccharides were determined by multiplex immunoassay.

RESULTS

In total, 113 preterm infants were included with similar baseline and nutritional characteristics in both groups. After 3 primary pneumococcal vaccinations, the scGOS/lcFOS/pAOS-group had lower GMC antibody concentrations (µg/mL; serotype 4: 1.53, 6B:0.25, 9V: 1.19, 14: 2.39, 18C: 1.88, 19F: 7.42, 23F: 0.72) than the placebo group (serotype 4: 3.29, 6B: 0.79, 9V:2.64, 14: 4.52, 18C: 3.13, 19F: 14.64, 23F: 1.88; all P < 0.05), but comparable with those in the term control group (serotype 4: 0.97, 6B: 0.32, 9V: 1.67, 14: 3.24, 18C: 2.03, 19F: 5.06, 23F: 0.59; all P > 0.05). After the booster vaccination at 11 months, antibody levels were no longer different between the two preterm groups.

CONCLUSION

Enteral supplementation of scGOS/lcFOS/pAOS has a regulatory effect on the response to conjugated polysaccharide pneumococcal vaccine with normalization of the enhanced responses in preterm infants toward levels similar to healthy term infants.

Adverse Events After Routine Immunization of Extremely Low-Birth-Weight Infants

IMPORTANCE

Immunization of extremely low-birth-weight (ELBW) infants in the neonatal intensive care unit (NICU) is associated with adverse events, including fever and apnea or bradycardia, in the immediate postimmunization period. These adverse events present a diagnostic dilemma for physicians, leading to the potential for immunization delay and sepsis evaluations.

OBJECTIVE

To compare the incidence of sepsis evaluations, need for increased respiratory support, intubation, seizures, and death among immunized ELBW infants in the 3 days before and after immunization.

DESIGN, SETTING, AND PARTICIPANTS

In this multicenter retrospective cohort study, we studied 13,926 ELBW infants born at 28 weeks' gestation or less who were discharged from January 1, 2007, through December 31, 2012, from 348 NICUs managed by the Pediatrix Medical Group.

EXPOSURES

At least one immunization between the ages of 53 and 110 days.

MAIN OUTCOMES AND MEASURES

Incidence of sepsis evaluations, need for increased respiratory support, intubation, seizures, and death.

RESULTS

Most of the 13,926 infants (91.2%) received 3 or more immunizations. The incidence of sepsis evaluations increased from 5.4 per 1000 patient-days in the preimmunization period to 19.3 per 1000 patient-days in the postimmunization period (adjusted rate ratio [ARR], 3.7; 95% CI, 3.2-4.4). The need for increased respiratory support increased from 6.6 per 1000 patient-days in the preimmunization period to 14.0 per 1000 patient-days in the postimmunization period (ARR, 2.1; 95% CI, 1.9-2.5), and intubation increased from 2.0 per 1000 patient-days to 3.6 per 1000 patient-days (ARR, 1.7; 95% CI, 1.3-2.2). The postimmunization incidence of adverse events was similar across immunization types, including combination vaccines when compared with single-dose vaccines. Infants who were born at 23 to 24 weeks' gestation had a higher risk of sepsis evaluation and intubation after immunization. A prior history of sepsis was associated with higher risk of sepsis evaluation after immunization.

CONCLUSIONS AND RELEVANCE

All ELBW infants in the NICU had an increased incidence of sepsis evaluations and increased respiratory support and intubation after routine immunization. Our findings provide no evidence to suggest that physicians should not use combination vaccines in ELBW infants. Further studies are needed to determine whether timing or spacing of immunization administrations confers risk for the developing adverse events and whether a prior history of sepsis confers risk for an altered immune response in ELBW infants.

Retrospective review of administration of childhood primary vaccination schedule in an Irish tertiary neonatal intensive care unit

AIMS

Quantify and evaluate administration of the routine childhood primary vaccination schedule in a tertiary neonatal intensive care unit (NICU).

STUDY DESIGN

Retrospective review of paper record of vaccinations administered to inpatients in the NICU from 01/01/2001-30/11/2013.

METHODS

Data were extracted from hospital records and institutional databases and analysed using SPSS for Mac version 21. Analysis was made based on gestational age, chronological age at time of administration of vaccine, corrected gestational age at time of vaccine administration and type of vaccine received.

RESULTS

For all preterm (gestation < 37 weeks) babies that received the first '6in1' vaccination while an inpatient (n = 344): mean gestational age = 27.3 weeks (sd = 2.6 weeks); mean chronological age at time of vaccination = 9.4 weeks. For all preterm patients that received the second '6in1' vaccination while an inpatient (n = 19): mean gestational age = 25.6 weeks (sd = 1.63); mean chronological age at time of vaccination = 18.4 weeks. For all term (gestation ≥ 37 weeks) patients that received the first '6in1' vaccination while an inpatient (n = 9): mean gestational age = 40.1 weeks (sd = 1.9); mean chronological age at time of vaccination = 9.8 weeks. There were no reported adverse events to any of the vaccinations administered.

CONCLUSION

It is safe for premature infants to receive the routine vaccination schedule in a NICU setting.

Improving preterm infants' immunisation status: a follow-up audit

AIM

Preterm infants are at increased risk of vaccine preventable diseases. An audit in 2007 identified suboptimal immunisation status of preterm infants. The aim of this study was to complete the 'audit loop', reviewing preterm infants' immunisation status at a single tertiary paediatric hospital.

METHODS

A retrospective follow-up immunisation audit was conducted at The Royal Children's Hospital, Melbourne, neonatal unit. The 'audit loop' included a preterm infants' reminder sticker and feedback of the original audit findings to Royal Children's Hospital health-care professionals. Immunisation status was determined using the Australian Childhood Immunisation Register record for all admitted preterm infants born <32 weeks gestation (July 2008-June 2009).

RESULTS

Conducted in March 2011, the median age of participants (n = 57) was 2.5 years (range 1.7-3.1 years). Forty-four per cent (25/57) had a history of chronic lung disease, 86% (49/57) were <1500 g and 42% (24/57) <28 weeks gestation. The majority (96% (55/57)) were up to date with routine immunisations at 12 months of age. There was a 2.4-fold increase, compared with the original audit, for receipt of the additional recommended hepatitis B vaccine at 12 months of age, as well as influenza vaccine in infants with chronic lung disease.

CONCLUSION

This study showed that a simple reminder combined with education strategies can improve vaccine delivery in special risk groups such as preterm infants.

Delayed start of diphtheria, tetanus, acellular pertussis and inactivated polio vaccination in preterm and low birth weight infants in the Netherlands

BACKGROUND

It is recommended that preterm (PT) and low birth weight infants be vaccinated according to standard guidelines. We studied the timeliness of the first diphtheria, tetanus, acellular pertussis and inactivated polio vaccination in the Netherlands, by gestational age (GA) and birth weight (BW).

METHODS

We included all vaccinated children born during 2006-2010. Data from the national immunization register were used to determine the vaccination age and the proportion of timely vaccinated infants (<70 days). Results were compared between groups based on GA (extreme PT: <32, PT: 32-36, full term (FT): ≥37 weeks) and BW. Characteristics associated with the timeliness of vaccination were studied by Cox regression analyses.

RESULTS

The median vaccination age was lower with a higher GA/BW. The proportion of timely vaccinated infants was 66% for extreme PT, 76% for PT and 82% for FT infants. Similar results were seen by BW. Overall, the proportion of timely vaccinated infants increased from 2006 (77%) until 2010 (85%) and there were regional differences and differences by ethnicity. In extreme PT and PT infants, living in a very highly urbanized municipality and being light for GA were associated with less timely vaccination. Being vaccinated in a hospital was associated with a timelier vaccination in extreme PT infants. However, the reverse was seen for PT infants.

CONCLUSIONS

In the Netherlands, PT and low birth weight infants were less often timely vaccinated than FT infants and were, therefore, at increased risk of vaccine-preventable infections. In FT infants, the timeliness of vaccination is better but could also be optimized.

Neutral and acidic oligosaccharides supplementation does not increase the vaccine antibody response in preterm infants in a randomized clinical trial

BACKGROUND

In preterm infants, a decreased immunological response and lower serological effectiveness are observed after immunizations due to ineffectiveness of both humoral and cellular immune mechanisms.

OBJECTIVE

To determine the effect of 80% neutral oligosaccharides [small-chain galacto-oligosaccharides/long-chain fructo-oligosaccharides (scGOS/lcFOS)] in combination with 20% pectin-derived acidic oligosaccharides (pAOS) on antibody concentrations after DTaP-IPV-Hib immunization in preterm infants.

DESIGN

In this randomized clinical trial, preterm infants with gestational age <32 weeks and/or birth weight <1500 g received enteral supplementation with scGOS/lcFOS/pAOS or placebo (maltodextrin) between days 3 and 30 of life. Blood samples were collected at 5 and 12 months of age.

RESULTS

In total, 113 infants were included. Baseline and nutritional characteristics were not different in both groups. Geometric mean titers were not different after prebiotic supplementation at 5 months, Ptx (37/44 EU/ml), FHA (78/96 EU/ml), Prn (78/80 EU/ml), Diphtheria (0.40/0.57 IU/ml), Tetanus (0.74/0.99 IU/ml) and Hib (0.35/0.63 µg/ml), and at 12 months Ptx (55/66 EU/ml), FHA (122/119 EU/ml), Prn (116/106 Eu/ml), Diphtheria (0.88/1.11 IU/ml), Tetanus (1.64/1.79 IU/ml) and Hib (2.91/2.55 µg/ml).

CONCLUSIONS

Enteral supplementation of neutral (scGOS/lcFOS) and acidic oligosaccharides (pAOS) does not improve the immunization response in preterm infants.

TRIAL REGISTRATION

Controlled-Trials.com ISRCTN16211826 ISRCTN16211826.

Blood stream infection is associated with altered heptavalent pneumococcal conjugate vaccine immune responses in very low birth weight infants

OBJECTIVE

Sepsis in older children and adults modifies immune system function. We compared serotype-specific antibody responses to heptavalent pneumococcal conjugate vaccine (PCV7) in very low birth weight infants (<1500 g,VLBWs) with and without blood stream infection (BSI) during their birth hospitalization.

STUDY DESIGN

Retrospective analysis of prospectively collected data for the Neonatal Research Network study of PCV7 responses among VLBWs. Infants received PCV7 at 2, 4 and 6 months after birth with blood drawn 4 to 6 weeks after third dose. Serotype antibodies were compared between infants with or without a history of BSI. Regression models were constructed with BW groups and other confounding factors identified in the primary study.

RESULT

In all, 244 infants completed the vaccine series and had serum antibody available; 82 had BSI. After adjustment, BSI was not associated with reduced odds of serum antibody 0.35 μg ml(-1).

CONCLUSION

BSI was not associated with reduced odds of World Health Organization-defined protective PCV7 responses in VLBWs.

Seroprevalance of pertussis antibodies in maternal and cord blood of preterm and term infants

BACKGROUND

The resurgence of pertussis has resulted in an increased morbidity and mortality, especially among young infants. The aim of our study was to determine the antibody concentrations against pertussis antigens in cord and maternal blood in both preterm and term infant-mother pairs and to evaluate the efficacy of transplacental antibody transfer.

METHODS

Antibodies to pertussis toxin (PT) and filamentous hemagglutinin (FHA) in maternal and cord blood samples were measured by in-house enzyme linked immunosorbent assay (ELISA) in 100 preterm infant-mother and 100 term infant-mother pairs. Geometric mean concentrations (GMCs) of pertussis antibodies and cord:maternal GMC ratios were calculated.

RESULTS

Cord GMCs for anti-PT and anti-FHA in the preterm group were 13.15 and 14.55 ELISA U/ml (EU/ml), respectively. Cord GMCs for anti-PT and anti-FHA in the term group were 19.46 and 19.18 EU/ml, respectively. Cord anti-PT GMC was significanlty lower in the preterm group (p=0.037). There were no differences between the groups with regard to maternal anti-PT and anti-FHA GMC. Placental transfer ratios for anti-PT and anti-FHA in preterms were 68% and 72%, respectively. The same ratios in terms were 107% and 120%, respectively and were significantly higher than those of preterms (p<0.001). Placental transfer ratios were even lower in preterms <32 weeks when compared to preterms ≥32 weeks and terms. There was a strong correlation between maternal and cord anti-pertussis antibody levels both in preterm and term infants.

CONCLUSIONS

Anti-pertussis antibody levels were generally low in infant-mother pairs and would not be adequate to confer protection until the onset of primary immunization series. Transplacental anti-pertussis antibody transfers and antibody levels were lower in the cord blood of preterm infants, especially in those <32 weeks. These findings support the rationale for maternal immunization, which in combination with cocooning, could be a better option for preterm infants.

Innate immune function by Toll-like receptors: distinct responses in newborns and the elderly

Given the "inborn" nature of the innate immune system, it is surprising to find that innate immune function does in fact change with age. Similar patterns of distinct Toll-like-receptor-mediated immune responses come to light when one contrasts innate immune development at the beginning of life with that toward the end of life. Importantly, these developmental patterns of innate cytokine responses correlate with clinical patterns of susceptibility to disease: A heightened risk of suffering from excessive inflammation is often detected in prematurely born infants, disappears over the first few months of life, and reappears toward the end of life. In addition, risk periods for particular infections in early life reemerge in older adults. The near-mirror-image patterns that emerge in contrasts of early versus late innate immune ontogeny emphasize changes in host-environment interactions as the underlying molecular and teleologic drivers.

Bordetella pertussis infection in a child with completed primary immunization: A case report

A 20 mo old male child, born at 31 weeks, presented to an out-of-hours General Practitioner (GP) with a 7 d history of cough and fever. There was history of post-tussive vomiting. On assessment a pernasal swab was cultured from which B. pertussis was isolated. This child had received a complete course of primary immunization. In the light of recent increase in Pertussis cases in the United Kingdom we would like to use this case report to increase the awareness among clinicians to the possibility of a diagnosis of whooping cough even in children with completed primary immunization and particularly in preterm infants.

The developing human preterm neonatal immune system: a case for more research in this area

Neonates, particularly those born prematurely, are among the most vulnerable age group for morbidity and mortality due to infections. Immaturity of the innate immune system and a high need for invasive medical procedures in the context of a preterm birth make these infants highly susceptible to common neonatal pathogens. Preterm infants who survive may also suffer permanent disabilities due to organ damage resulting from either the infection itself or from the inflammatory response generated under an oxidative stress. Infections in preterm infants continue to pose important healthcare challenges. Yet, developmental maturation events in the innate immune system that underlie their excessively high vulnerability to infection remain largely understudied. In this review article, we identify pertinent knowledge gaps that must be filled in order to orient future translational research.

Incidence of adverse events in premature children following 2-month vaccination

Using a population based self-controlled case series study design we examined data on 834,740 children in the province of Ontario, Canada. We observed that when comparing to SGA10 term children (term children born in the lowest 10th percentile of weight for a given gestational age), relative incidence of emergency room visits and admission in the 3 d post 2 mo vaccination progressively decreased in near term (relative incidence ratio 0.89 (95% CI 0.74-1.07)) and very premature children [(0.67(0.49-0.93)]. When compared with all term children this decrease in risk is not statistically significant. We speculate that the immune response is reduced in premature children resulting in reduced adverse events. This is masked when comparing to all term children because the reduced birth weight of premature children results in a comparatively increased dose of vaccine. This in turn results in an increased immune response and risk of immediate adverse reactions. Future studies of immune response in premature children should examine the impact of weight at the time of immunization.

Mother-infant transfer of anti-human papillomavirus (HPV) antibodies following vaccination with the quadrivalent HPV (type 6/11/16/18) virus-like particle vaccine

The exploratory immunogenicity objective of this analysis was to characterize the titer of vaccine human papillomavirus (HPV)-type immunoglobulins in both peripartum maternal blood and the cord blood of infants born to women who received blinded therapy. Data were derived from a randomized, placebo-controlled, double-blind safety, immunogenicity, and efficacy study (protocol 019; NCT00090220). This study enrolled 3,819 women between the ages of 24 and 45 years from 38 international study sites between 18 June 2004 and 30 April 2005. Data in the current analysis are from subjects enrolled in Philippines and Thailand. For each of HPV types 6, 11, 16, and 18, maternal anti-HPV was found in cord blood samples. Furthermore, HPV titers in cord blood samples were highly positively correlated with maternal HPV titers. Additionally, there were instances when anti-HPV antibodies were no longer detectable in maternal serum samples and yet were detected in matched cord blood samples. These results demonstrate that quadrivalent HPV (qHPV) vaccine-induced antibodies cross the placenta and could potentially provide some benefit against vaccine-type HPV infection and related diseases such as recurrent respiratory papillomatosis.

Protective effect of hepatitis B vaccine combined with two-dose hepatitis B immunoglobulin on infants born to HBsAg-positive mothers

BACKGROUND

Despite the use of hepatitis B (HB) vaccine and hepatitis B immunoglobulin (HBIG), a portion of infants are still non- or low-responders, or even immunoprophylaxis failure. We aimed to determine the immune response in the infants from the mothers being positive for hepatitis B surface antigen (HBsAg), by which the infants received three doses of HB vaccine in combination with two-dose 200 IU HBIG injections.

METHODS

In this retrospective study, 621 infants from HBsAg-positive mothers in Beijing YouAn Hospital between January 2008 and December 2009 were included. All the infants were given three doses of 10 µg HB vaccine (at 0, 1 and 6 months of age) and two-dose of 200 IU HBIG (at birth and in 2 weeks of age). Serum HBsAg and antibody to HBsAg (anti-HBs) in all the infants were determined at 7 months of age.

RESULTS

Of the 621 infants, 2.9% were immunoprophylaxis failure (positive for HBsAg), 1.4% were non-responders (anti-HBs undetectable), 95.7% were responders. The 594 responders could be categorized into three subsets, 22 were 10 to 99 IU/L for anti-HBs levels, 191 were 100 to 999 IU/L, and 381 were ≥1000 IU/L. The immunoprophylaxis failure rate was at 0% and 5.2% for the infants of HBeAg-negative and HBeAg-positive mothers(P<0.001). Infants from mothers with detectable HBV DNA had higher incidence of immunoprophylaxis failure than those of mothers without detectable HBV DNA (P = 0.002). The factors including gender, birth weight, gestation weeks, the rates of maternal HBeAg-positive, and detectable HBV DNA did not contribute to the no response to HB vaccination.

CONCLUSIONS

Through vaccination by three doses of HB and two-dose of HBIG, majority of the infants (95.7%) achieved a protective level of anti-HBs at 7 months of age. Maternal HBeAg-positive and HBV DNA detectable were associated with the immunoprophylaxis failure, but not contribute to the non- or low-response to HB vaccination.

How the immune response to vaccines is created, maintained and measured: addressing patient questions about vaccination

This article gives an overview of the immune response to vaccines, including ways in which it is measured and/or augmented to enhance its effectiveness. A brief description is given of the immune response, adaptive immunity, immunologic memory, antibodies, and adjuvants. Given that many young parents and physicians have never witnessed the ravages of vaccine-preventable diseases, it is hoped this article will aid the many people involved in the prevention of infectious disease to understand better the concepts and practicalities of immunization and vaccine development.

Impact of birth weight at term on rates of emergency room visits and hospital admissions following vaccination at 2 months of age

BACKGROUND

Birth weight of children born at term may theoretically be associated with risk of adverse events from immunization.

METHODS

We analyzed data on children born between April 1st 2002 and March 31st 2009 in the province of Ontario. Using the self-controlled case series design, we examined the risk of the combined endpoint of emergency room visit and hospital admission in the immediate three days post vaccination at 2 months of age compared to a control period 9-18 days after vaccination. In term children, we conducted 4 comparisons of relative incidence (RI) of events: (1) 4 lower birth weight quintiles compared to the largest quintile (2) SGA10 infants compared to non SGA10 infants, (3) low birth weight infants (<2500g) compared to non low birth weight infants and (4) SGA10 infants vaccinated before 60 days compared to those vaccinated after 60 days.

RESULTS

There was a significant trend towards increasing relative incidence of the combined endpoint with decreasing birth weight quintile (p=0.016). There was an increased relative incidence of events in SGA10 versus non SGA10 infants (RI 1.25 (95% CI 1.09-1.44)) and in SGA10 children vaccinated before 60 days of age compared to after 60 days of age (RI 1.57 (95% CI 1.14-2.18)). No significant effect was observed in low birth weight children. The impact of birth weight was primarily mediated through an increase in ER visits in the 24h following vaccination.

CONCLUSION

Lower birth weight appears to be correlated with an increased risk of emergency room visits within 24h of vaccination. The absolute risk is small and there was no impact on admissions or death.

Immunogenicity and safety of heptavalent conjugate vaccine against Streptococcus pneumoniae in pre-term Polish infants

The purpose of the study was to assess post-vaccination immune response and occurrence of adverse events in the group of prematurely born infants. The study included 40 pre-term infants. Each child was vaccined four times (2, 4, 6 and 16 months) with the heptavalent conjugated pneumococcal vaccine (PCV7). Assessing of the level of antibodies was performed before vaccination, 4 weeks after primary series, before and 4 weeks after the booster dose. The research participants were qualified into 2 groups: group I - 19 children born before 30th gestational week, group II - 21 children born between the 30th and 34th gestational week. After the basic vaccination, an increase in the average antibody concentration in the area of all serotypes in most of the children tested was registered, with no significant differences observed between the groups. However, differences between individual serotypes were observed. The lowest values were found for serotype 6B. Before administering the booster dose, a significant drop in antibody titre in all of the children tested was noted. The last vaccination caused another significant increase in antibody concentration in both groups and the results obtained were markedly higher than those obtained after administering three vaccine doses. The majority of the children tested (with the exception of three from group II) achieved the preventive antibody level ≥ 0.35 μg/ml. In all of the children, no serious adverse events were observed. Our research showed, that heptavalent pneumococcal conjugate vaccine is immunogenic in children born before the completion of the 34th week of pregnancy. A booster dose of vaccine must be given at the right time to optimal response to the vaccine for all serotypes. Finally, any serious adverse events were observed.

Update on immunizations commonly used in the NICU

With few exceptions, it is currently recommended that all premature infants should receive routine childhood vaccines at the same chronologic age as term infants. Thus, neonatal nurses need to stay current on the recommendations for immunizations commonly used in the NICU setting. It is important for nurses to provide information that is reliable and verifiable with scientific evidence to the parents.

Optimizing immunization in pediatric special risk groups

This article analyzes the current recommended practices and evidence in the immunization of pediatric 'special risk groups'. Special risk group patients are at higher risk of vaccine-preventable diseases and hence require additional strategies to maximize protection against these diseases. The special risk groups include those with an underlying chronic disease, some of whom are on immunosuppressive therapy to treat that condition. The article uses four special risk groups (acute lymphoblastic leukemia; preterm birth; juvenile idiopathic arthritis; and inflammatory bowel disease), to highlight the management considerations and potential vaccination strategies. The risks, benefits and timing of vaccination in the setting of immunosuppression require detailed discussion with treating clinicians, in particular the use of live-attenuated vaccines. The immunogenicity of vaccines in these special risk groups helps provide the evidence base for their immunization guidelines. Protection can include 'cocooning' (i.e., ensuring appropriate immunizations within the immediate family; e.g., varicella, influenza and pertussis vaccination). Improving timeliness and minimizing missed opportunities to vaccinate individuals with these special risk conditions will also optimize protection from vaccine-preventable diseases.

Transplacental transport of IgG antibodies to preterm infants: a review of the literature

Newborn infants, especially preterm infants, have an immature immune system, which is not capable to actively protect against vaccine-preventable infections. Therefore, the newborn is dependent on transplacental transport of Immunoglobulin G (IgG), an active, FcRn receptor mediated process. Fetal IgG rises from approximately 10% of the maternal concentration at 17-22weeks of gestation to 50% at 28-32weeks of gestation. If transplacental acquired IgG is lower in preterm than in term infants, preterm infants are especially at risk for these vaccine-preventable diseases. The aim of this study was to review the transplacental transfer of IgG against vaccine-preventable diseases (measles, rubella, varicella-zoster, mumps, Haemophilus influenza type B, diphtheria, tetanus, pertussis and polio) to (pre)term infants and to identify factors that influence the transplacental transfer of these antigens. After selection, 18 studies on transplacental transport to preterm infants were included. In general, these studies showed for all antibodies that preterm infants have lower antibody concentrations compared with term infants. Maternal and infants antibody concentrations showed a strong correlation in 7 of the included studies. Infant antibody concentration was not associated with parity, maternal age, height or weight. Infants of vaccinated mothers had lower anti-measles antibody titers than infants of natural immunized mothers. IgG titers of preterm infants decrease earlier in life below protective antibody titers than term infants. Combined with their immature immune system, this puts preterm infants at increased risk for vaccine-preventable diseases.

Transplacental transport of IgG antibodies specific for pertussis, diphtheria, tetanus, haemophilus influenzae type b, and Neisseria meningitidis serogroup C is lower in preterm compared with term infants

BACKGROUND

Maternal antibodies, transported through the placenta during pregnancy, contribute to the protection of infants from infectious diseases during the first months of life. The aim of this study was to measure the concentration of antibodies against several vaccine-preventable diseases in paired maternal and cord blood serum samples in preterm and term infants and to assess placental transfer ratios and infant antibody concentrations against vaccine-preventable diseases.

METHODS

Antibody concentrations specific against pertussis proteins (pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae), diphtheria and tetanus toxins, and antibody concentrations specific against polysaccharides from Haemophilus influenzae type b and Neisseria meningitidis serogroup C were measured in cord blood samples from preterm (<32 weeks and 1500 g) and term infants and maternal serum samples, using a fluorescent bead-based multiplex immunoassay.

RESULTS

A total of 96 preterm and 42 term infants and their mothers were included in the study. Placental transfer ratios of antibodies against all vaccine antigens were significantly lower in preterm infants (medians varied from 0.26 to 0.86) compared with term infants (medians, 0.74-1.89; all antibodies P < 0.05). Furthermore, polysaccharide-vaccine-specific antibodies showed lower transplacental transport ratios than protein-vaccine-specific antibodies. Maternal concentrations are the most important determinants of infant antibody concentrations against vaccine-preventable diseases.

CONCLUSIONS

Preterm infants benefit to a lesser extent from maternal antibodies against vaccine-preventable diseases than term infants, posing them at higher risk for infectious diseases in the first months of life.

The challenge of assessing infant vaccine responses in resource-poor settings

Newborns and infants are highly susceptible to infectious diseases, resulting in high mortality and morbidity, particularly in resource-poor settings. Many vaccines require several booster doses, resulting in an extensive vaccine schedule, and yet there is still inadequate protection from some of these diseases. This is partly due to the immaturity of the neonate and infant immune system. Little is known about the specific modifications to immunological assessment protocols in early life but increasing knowledge of infant immunology has helped provide better recommendations for assessing these responses. Since most new vaccines will eventually be deployed in low-income settings such as Africa, the logistics and resources of assessing immunity in such settings also need to be understood. In this article, we will review immunity to vaccines in early life, discuss the many challenges associated with assessing immunogenicity and provide practical tips.

Effect of heptavalent pneumococcal conjugate vaccination on invasive pneumococcal disease in preterm born infants

Background

Evidence for protection of preterm born infants from invasive pneumococcal disease (IPD) by 7-valent pneumococcal conjugate vaccination (PCV7) is relatively sparse. Data from randomized trials is based on relatively small numbers of preterm born children.

Methods

We report data from active prospective surveillance of IPD in children in Germany. The cohorts of preterm born children in 2000 and 2007 and the respective whole birth cohorts are compared regarding occurrence of IPD.

Results

After introduction of PCV7 we observed a reduction in the rate of IPD in preterm born infants comparing the 2000 and 2007 birth cohort. The rate of IPD among the whole birth cohorts was reduced from 15.0 to 8.5 notifications per 100,000 (P < .001). The impact among the preterm birth cohort was comparable: A reduction in notification rate from 26.1 to 16.7 per 100,000 comparing the 2000 with the 2007 preterm birth cohort (P = .39). Preterm born infants with IPD were either unvaccinated or vaccinated delayed or incomplete.

Conclusions

This adds to evidence that PCV7 also protects preterm born infants effectively from IPD. Preterm born infants should receive pneumococcal vaccination according to their chronological age.

The mother's immune system is a balanced threat to the foetus, turning to protection of the neonate

Immunological tolerance by the mother prevents rejection of the foetus, but aberrations may increase risk of abnormalities like spontaneous abortion, or foetal growth restriction. The neonate is normally colonized with mother's gut microflora, mainly composed of protective anaerobes. This least threatening form of microbial colonization of the neonate, is impaired by sectio delivery, but supported by breastfeeding. Mother's transplacental IgG, secretory IgA and other milk components help protect the neonate together with its own slowly expanding immune system.

CONCLUSION

The mother's immune system tolerates her foetus via several mechanisms. Failure to do so may cause foetal growth retardation, or spontaneous abortion. The mother and the neonate cooperate in preventing infections in the offspring.

Recurrence of cardiorespiratory events following repeat DTaP-based combined immunization in very low birth weight premature infants

We evaluated the tolerance to immunization of 64 very low birth weight preterm infants. Thirty-three of the infants experienced a cardiorespiratory event after the first vaccination, and 6 of these 33 (18%) had a recurrence after the second vaccination, including 2 infants previously discharged to home. A cardiorespiratory event associated with the first vaccination was the sole risk factor for recurrence identified.