Immunization of preterm infants

Penta- and hexavalent vaccination of extremely and very-to-moderate preterm infants born at less than 34 weeks and/or under 1500 g: A systematic literature review

Debate regarding vaccinating high-risk infants with penta- and hexavalent vaccines persists, despite their good immunogenicity and acceptable safety profile in healthy full-term infants. We report the findings of a systematic literature search that aimed to present data on the immunogenicity, efficacy, effectiveness, safety, impact, compliance and completion of penta- and hexavalent vaccination in high-risk infants, including premature newborns. Data from the 14 studies included in the review showed that the immunogenicity and the safety profile of penta- and hexavalent vaccines in preterm infants was generally similar to those seen in full-term infants, with the exception of an increase in cardiorespiratory adverse events such as apnea, bradycardia and desaturation following vaccination in preterm infants. Despite recommendations of vaccinating preterm infants according to their actual age, and the relatively high completion rate of the primary immunization schedule, vaccination was often delayed, increasing the vulnerability of this high-risk population to vaccine-preventable diseases.

Antibody deficiencies in children are associated with prematurity and a family history of infections

BACKGROUND

Recurrent respiratory tract infections (rRTIs) frequently affect young children and are associated with antibody deficiencies. We investigated the prevalence of and epidemiological risk factors associated with antibody deficiencies in young children with rRTIs and their progression over time, and linked these to prospectively measured RTI symptoms.

METHODS

We included children <7 years with rRTIs in a prospective cohort study. Patient characteristics associated with antibody deficiencies were identified using multivariable logistic regression analysis.

RESULTS

We included 146 children with a median age of 3.1 years. Daily RTI symptoms were monitored in winter in n = 73 children and repeated immunoglobulin level measurements were performed in n = 45 children. Antibody deficiency was diagnosed in 56% and associated with prematurity (OR 3.17 [1.15-10.29]) and a family history of rRTIs (OR 2.37 [1.11-5.15]). Respiratory symptoms did not differ between children with and without antibody deficiencies. During follow-up, antibody deficiency diagnosis remained unchanged in 67%, while 18% of children progressed to a more severe phenotype.

CONCLUSION

Immune maturation and genetic predisposition may lie at the basis of antibody deficiencies commonly observed in early life. Because disease severity did not differ between children with and without antibody deficiency, we suggest symptom management can be similar for all children with rRTIs.

IMPACT

An antibody deficiency was present in 56% of children <7 years with recurrent respiratory tract infections (rRTIs) in a Dutch tertiary hospital setting. Prematurity and a family history of rRTIs were associated with antibody deficiencies, suggesting that immune maturation and genetic predisposition may lie at the basis of antibody deficiencies in early life. RTI symptoms did not differ between children with and without antibody deficiency, suggesting that symptom management can be similar for all children with rRTIs, irrespective of humoral immunological deficiencies. During follow-up, 18% of children progressed to a more severe phenotype, emphasizing that early diagnosis is warranted to prevent long-term morbidity and increase quality of life.

Evaluation of vaccination status of children with special health care needs in Suzhou, China, 2020-2022: A retrospective survey study

Children with special health care needs (CSHCNs) are at an increased risk of vaccine-preventable infections (VPDs), but they also face the dilemma of vaccine hesitancy. We obtained information on pediatric visits from the Referral and Assessment Information System for Vaccination (RAISV) and information on vaccination from the Jiangsu Province Immunization Information System (JSIIS). We followed the occurrence of Adverse Events Following Immunization (AEFIs) and VPDs by actively calling and querying the China Information System for Disease Control and Prevention (CISDCP). The Poisson test was used to compare the incidence of AEFIs between groups. A total of 5,037 children who visited a vaccination assessment clinic were followed-up in this study. The majority were children with developmental anomalies (28.5%), certain conditions originating in the perinatal period (12.1%), and nervous system disorders (9.0%). Most CSHCNs (66.9%) were advised to have all vaccines according to routine practice, 29.0% were advised to have partial vaccination, and 4.1% were advised to delay all vaccines and wait for future assessment. A total of 201 (4.0%) CSHCNs were not vaccinated, although they were assessed to be eligible for vaccination. By querying the immunization planning module in CISDCP, we observed 55 AEFI cases, which amounted to an incidence rate of 1.2 per 1,000, and the occurrence of abnormal reactions was not significantly different compared with the general population. The vaccination program following the designed workflow for CSHCNs was safe and could be recommended in other areas.

An update on vaccination in preterm infants

OBJECTIVE

The objective of this article is to review the most current literature on vaccines, focusing on their safety, immunogenicity, and efficacy in preterm newborns, aiming to improve vaccine coverage in this population.

DATA SOURCE

Most recent scientific publications addressing the immunization of preterm newborns.

DATA SYNTHESIS

Despite its immunological immaturity, vaccination is well tolerated by preterm infants, and protective immune responses are observed, but some studies have shown that preterm infants undergo unjustified delays in their vaccination schedule.

CONCLUSIONS

Despite being widely recommended, the routine immunization of preterm infants is often delayed, putting this vulnerable population at risk for several diseases, many of which are preventable by immunization. Every effort should be made to develop universal guidelines that define the immunization of preterm infants.

A retrospective study of hepatitis B vaccination in preterm birth and low birth weight infants born to hepatitis B surface antigen-positive mothers: Time to close the policy-practice gap

National Immunization Program-version 2016 (ISIV-NIP-v2016) recommended a 4-dose hepatitis B vaccine (HepB) schedule for preterm birth (PTB) and low birth weight (LBW) infants born to HBsAg-positive mothers. However, the implementation of this immunization strategy in the past five years has not been fully evaluated in China. We reviewed the data of pregnant women and live-born infants from 24 hospitals between 2016 and 2021 in Lu'an, Anhui province, to estimate the prevalence of PTB, LBW, and hepatitis B virus (HBV) infected pregnant women. We analyzed the vaccination status of HepB and HBIG among PTB and LBW infants born to HBsAg-positive mothers. A total of 160 222 pregnant women and 159 613 live-born infants were included in this study. The estimated prevalence of PTB, LBW and HBV-infected pregnant women was 3.86% (range: 3.28%-5.10%), 2.77% (range: 2.12%-3.66%), and 3.27% (range: 3.03%-3.49%), respectively. We screened 340 PTB and LBW infants born to HBsAg-positive mothers between 2016 and 2020. We found that the coverage of HepB and HBIG among them was 100% and 99.39%. However, the timely vaccination rate of the HepB birth dose was only 78.59% and only four children (1.22%) received the 4-dose HepB as recommended by ISIV-NIP-v2016. The 4-dose of HepB for PTB and LBW infants born to HBsAg-positive mothers recommended by ISIV-NIP-v2016 was not fully implemented. A strong public health intervention should be taken to close the policy-practice gap in China in the future.

Le suivi de l'extrême prématuré après le congé des soins intensifs néonatals

La survie des extrêmes prématurés (moins de 28 semaines d'âge gestationnel) s'est améliorée au fil du temps. Bon nombre s'en sortent bien et ont une bonne qualité de vie. Ils demeurent toutefois vulnérables à des problèmes de santé, y compris des difficultés neurosensorielles et neurodéveloppementales, que les médecins de première ligne, les pédiatres et les cliniques spécialisées doivent surveiller. Le présent document de principes passe en revue les conséquences médicales et neurodéveloppementales potentielles pour les extrêmes prématurés dans les deux ans suivant leur congé et fournit des stratégies de counseling, de dépistage précoce et d'intervention. Parce qu'ils sont tous liés à l'extrême prématurité, la dysplasie bronchopulmonaire ou les troubles respiratoires, les problèmes d'alimentation et de croissance, le développement neurosensoriel (vision et audition), la paralysie cérébrale et le trouble du spectre de l'autisme doivent faire rapidement l'objet d'une évaluation. Pour évaluer la croissance et le développement, il faut corriger l'âge chronologique en fonction de l'âge gestationnel jusqu'à 36 mois de vie. Par ailleurs, l'attention au bien-être émotionnel des parents et des proches fait partie intégrante des soins de qualité de l'extrême prématuré.

Follow-up care of the extremely preterm infant after discharge from the neonatal intensive care unit

The survival of babies born extremely preterm (EP, <28 weeks gestation) has improved over time, and many have good outcomes and quality of life. They remain at risk for health issues, including neurosensory and neurodevelopmental difficulties requiring monitoring by primary physicians, paediatricians, and specialty clinics. This statement reviews potential medical and neurodevelopmental consequences for EP infants in the first 2 years after discharge and provides strategies for counselling, early detection, and intervention. EP-related conditions to assess for early include bronchopulmonary dysplasia or respiratory morbidity, feeding and growth concerns, neurosensory development (vision and hearing), cerebral palsy, and autism spectrum disorder. Correction for gestational age should be used for growth and development until 36 months of age. Integral to quality care of the child born EP is attention to the emotional well-being of parents and caregivers.

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.

Do Pediatricians and Nurses Recommend Vaccines for Preterm Infants? A Survey in Italy

OBJECTIVE

To assess the level of knowledge, attitudes, and behaviors regarding vaccination in preterm infants among primary care pediatricians (PCPs) and health care workers (HCWs) in neonatal intensive care units (NICUs).

STUDY DESIGN

Data were collected from PCPs through a confidential questionnaire distributed by email, whereas the research team distributed a self-administered anonymous questionnaire to all HCWs working in the selected NICUs.

RESULTS

Overall, 64.1% of HCWs consider vaccines in preterm infants to be very safe. The majority of HCWs (69.8%) stated that they always recommend that preterm infants' parents vaccinate their children following the same schedule as for term infants. This behavior was significantly more likely among those who know that the vaccination schedule for preterm infants is the same as for term infants, who consider vaccines in preterm infants very effective, and who strongly agree that preterm infants should be vaccinated on the same schedule as term infants. Moreover, PCPs were more likely than NICU pediatricians to always recommend that preterm infants' parents vaccinate their children following the immunization schedule of term infants, whereas this behavior was significantly less frequent among NICU nurses.

CONCLUSIONS

There is a need for physicians and nurses in the NICU and in the community to counteract missed or delayed immunizations. Engagement of HCWs in healthcare quality improvement initiatives focused on the promotion of timely vaccinations in preterm infants should be encouraged.

[Expert consensus on the follow-up management of bronchopulmonary dysplasia in preterm infants after discharge]

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in preterm infants and seriously affects the quality of life of preterm infants. BPD is a life-threatening disease to preterm infants and may lead to serious sequelae including feeding difficulties, recurrent lower respiratory tract infection, airway hyperreactive diseases, growth retardation, and neurodevelopmental delay. In order to further standardize the follow-up management of preterm infants with BPD after discharge, based on related clinical evidence in China and overseas and practice experience, the Neonatal Evidence-Based Medicine Group, Committee of Neonatal Medicine, Cross-Strait Medical and Health Exchange Association, formulated this expert consensus from the aspects of the follow-up and management of respiratory diseases, growth and development, pulmonary hypertension, nerve dysplasia, metabolic bone disease, and vaccination of preterm infants with BPD after discharge.

A Non-Invasive Neonatal Signature Predicts Later Development of Atopic Diseases

Background: Preterm birth is a major cause of morbidity and mortality in infants and children. Non-invasive methods for screening the neonatal immune status are lacking. Archaea, a prokaryotic life domain, comprise methanogenic species that are part of the neonatal human microbiota and contribute to early immune imprinting. However, they have not yet been characterized in preterm neonates. Objective: To characterize the gut immunological and methanogenic Archaeal (MA) signature in preterm neonates, using the presence or absence of atopic conditions at the age of one year as a clinical endpoint. Methods: Meconium and stool were collected from preterm neonates and used to develop a standardized stool preparation method for the assessment of mediators and cytokines and characterize the qPCR kinetics of gut MA. Analysis addressed the relationship between immunological biomarkers, Archaea abundance, and atopic disease at age one. Results: Immunoglobulin E, tryptase, calprotectin, EDN, cytokines, and MA were detectable in the meconium and later samples. Atopic conditions at age of one year were positively associated with neonatal EDN, IL-1β, IL-10, IL-6, and MA abundance. The latter was negatively associated with neonatal EDN, IL-1β, and IL-6. Conclusions: We report a non-invasive method for establishing a gut immunological and Archaeal signature in preterm neonates, predictive of atopic diseases at the age of one year.

Immunization of preterm infants: current evidence and future strategies to individualized approaches

Preterm infants are at particularly high risk for infectious diseases. As this vulnerability extends beyond the neonatal period into childhood and adolescence, preterm infants benefit greatly from infection-preventive measures such as immunizations. However, there is an ongoing discussion about vaccine safety and efficacy due to preterm infants' distinct immunological features. A significant proportion of infants remains un- or under-immunized when discharged from primary hospital stay. Educating health care professionals and parents, promoting maternal immunization and evaluating the potential of new vaccination tools are important means to reduce the overall burden from infectious diseases in preterm infants. In this narrative review, we summarize the current knowledge about vaccinations in premature infants. We discuss the specificities of early life immunity and memory function, including the role of polyreactive B cells, restricted B cell receptor diversity and heterologous immunity mediated by a cross-reactive T cell repertoire. Recently, mechanistic studies indicated that tissue-resident memory (Trm) cell populations including T cells, B cells and macrophages are already established in the fetus. Their role in human early life immunity, however, is not yet understood. Tissue-resident memory T cells, for example, are diminished in airway tissues in neonates as compared to older children or adults. Hence, the ability to make specific recall responses after secondary infectious stimulus is hampered, a phenomenon that is transcriptionally regulated by enhanced expression of T-bet. Furthermore, the microbiome establishment is a dominant factor to shape resident immunity at mucosal surfaces, but it is often disturbed in the context of preterm birth. The proposed function of Trm T cells to remember benign interactions with the microbiome might therefore be reduced which would contribute to an increased risk for sustained inflammation. An improved understanding of Trm interactions may determine novel targets of vaccination, e.g., modulation of T-bet responses and facilitate more individualized approaches to protect preterm babies in the future.

Vaccination rates and adherence in premature infants before and after pneumococcal conjugate vaccine schedule change for term infants - A claims database analysis in Germany

BACKGROUND

In 2015, the German Standing Committee on Vaccination (STIKO) changed the pneumococcal conjugate vaccination (PCV) schedule for mature infants from a 3+1scheme (2, 3, 4, and 11-14 months of age) to a 2+1scheme (2, 4, and 11-14 months of age). For premature infants, the 3+1scheme remained. The aim of this study was to assess vaccination rates, completeness, and timeliness for PCV in premature infants before and after the modified recommendation.

METHODS

A retrospective claims data analysis using the "Institut für angewandte Gesundheitsforschung Berlin" Research Database was conducted. Premature infants born in 2013 and 2016 with an individual follow-up of 24 months were included. Hexavalent combination (HEXA) vaccination with a consistent 3+1recommendation for mature and premature infants was analyzed as reference vaccination.

RESULTS

After 24 months, the PCV rate for at least one dose remained stable in premature newborns of 2016 compared to 2013, while the HEXA vaccination rate increased slightly. However, a significant decrease of a completed PCV schedule (4 doses) in premature infants was noted, whereas the completeness of HEXA vaccination did not change. The timeliness of PCV in premature newborns increased for the first and the booster PCV, while the timeliness of HEXA immunization did not change from 2013 to 2016.

CONCLUSION

Although STIKO still recommends a 3+1PCV schedule for premature infants in Germany, premature infants were vaccinated according to the changed recommendations for mature born infants. A substantial share of premature infants remained unvaccinated, and their vaccinations were often delayed.

Cost-Minimization and Budget Impact Analysis of a Hexavalent Vaccine (Hexaxim®) in the Colombian Expanded Program on Immunization

OBJECTIVES

To evaluate cost implications of a hexavalent vaccine (diphtheria, tetanus, and acellular pertussis [DTaP]-inactivated polio vaccine [IPV]-hepatitis B [HB]-Haemophilus influenzae type B [Hib] polysaccharide conjugated to T protein [PRP∼T]) as an alternative to DT-whole-cell pertussis (wP)-HB//Hib, DTwP, IPV, and oral polio vaccines in the Expanded Program on Immunization schedule in Colombia.

METHODS

Primary vaccination (DTaP-IPV-HB-PRP∼T or DTwP-HB-Hib + IPV [2, 4, 6 months]) and booster (DTaP-IPV-HB-PRP∼T or DTwP + oral polio vaccine [18 months]) (scenario 1) and primary vaccination only (DTaP-IPV-HB-PRP∼T or DTwP-HB-Hib + IPV) (scenario 2) were evaluated. An estimated cost-minimization analysis was based on a micro costing technique for vaccination-associated activities. Adverse event (AE)-associated costs, out-of-pocket costs, and productivity losses for caregivers were included. A budget impact (12-month temporal horizon) was estimated according to the distribution of full-term and premature infants. A 5% annual discount rate was used. A 2-way univariate (tornado) analysis evaluated which variables had the greatest impact on the overall cost.

RESULTS

DTaP-IPV-HB-PRP∼T resulted in a cost increase of 29.38% (scenario 1) and 22.19% (scenario 2) for full-term infants and a decrease of 0.99% (scenario 1) and 18.88% (scenario 2) for premature infants, probably because of the higher incidence of wP-related AEs and associated costs in premature infants. With a 100% replacement rate, the budget impact for full-term infants and full-term plus premature infants was 0.2373% and 0.2180% (scenario 1), respectively, and 0.1302% and 0.1114% (scenario 2), respectively, of the national immunization program budget. The variables with most impact were the hexavalent vaccine price and costs associated with the pentavalent safety profile.

CONCLUSIONS

Incorporation of the hexavalent vaccine in the Expanded Program on Immunization schedule would lead to an increase in spending largely mitigated by reduced AE incidence and reduced logistic and social costs.

Major cardiorespiratory events do not increase after immunizations, eye exams, and other stressors in most very low birth weight infants

BACKGROUND

Increased cardiorespiratory events with bradycardia and oxygen desaturation have been reported in very low birthweight (VLBW) infants following stressors such as immunizations. These events are difficult to quantify and may be mild. Our group developed an automated algorithm to analyze bedside monitor data from NICU patients for events with bradycardia and prolonged oxygen desaturation (BDs) and used this to compare BDs 24 hours before and after potentially stressful interventions.

METHODS

We included VLBW infants from 2012-2017 with data available around at least one of four interventions: two-month immunizations, retinopathy of prematurity (ROP) examinations, ROP therapy, and inguinal hernia surgery. We used a validated algorithm to analyze electrocardiogram heart rate and pulse oximeter saturation data (HR, SpO2) to quantify BD events of HR <  100 beats/minute for≥4 seconds with oxygen desaturation <  80%SpO2 for≥10 seconds. BDs were analyzed 24 hours before and after interventions using Wilcoxon rank-sum tests.

RESULTS

In 354 of 493 (72%) interventions, BD frequency stayed the same or decreased in the 24 hours after the event. An increase of at least five BD's occurred in 17/146 (12%) after immunizations, 85/290 (29%) after ROP examinations, 4/33 (12%) after ROP therapy, and 3/25 (12%) after hernia surgery. Infants with an increase in BDs after interventions had similar demographics compared to those without. More infants with an increase in BDs following immunizations were on CPAP or caffeine than those without.

CONCLUSIONS

Most VLBW infants in our cohort had no increase in significant cardiorespiratory events in the 24 hours following potentially stressful interventions.

Evaluation of immunogenicity after first dose of hepatitis B vaccine in newborns with very low birth weight

OBJECTIVE

Hepatitis-B virus (HBV) infection is an important health problem worldwide. HBV vaccine application varies according to the birth weight and gestational week in the neonatal period. This study aimed to reconsider delaying the administration of the HBV vaccine because the birth weight of newborns was very low.

METHODS

The newborns with very low birth weight in the study group were babies weighing less than 2000 g in the postnatal first month and at the time of administering HBV vaccine. Babies born at term from mothers who did not receive an HBV vaccine, had negative hepatitis B surface antibody levels, and were given HBV vaccine at birth were included in the study as a control group. The antibody levels against HBV vaccine were compared between these two groups.

RESULTS

The retrospective study included 60 participants (32 men and 28 women) grouped as control first vaccine weight (first vaccine weight was >2000 g, control group, n = 30) and case vaccine weight (first vaccine weight was <2000 g, case group, n = 30). The mean birth weight was 2976 ± 84.8 g and 1054 ± 44.5 g in the control and case groups, respectively. The first vaccine weight was 2030-3780 g and 960-1900 g in the control and case groups, respectively. The mean antibody level was 297.8 ± 76.3IU/mL and 309.7 ± 56.3IU/mL in the <1500 g and >1500 g groups, respectively. No significant difference was found in hepatitis antibody levels between the groups.

CONCLUSION

Further studies in larger samples are needed to confirm the efficacy and efficiency of postponement of hepatitis B vaccination in babies with a birth weight of <2000 g.

Vaccination timeliness and completeness among preterm and low birthweight infants: a national cohort study

Vaccinating premature and low birthweight (LBW) infants according to chronological age has been found safe and effective. Although these infants are susceptible to infections, vaccinations are often delayed. We estimated vaccination coverage (VC) in preterm and LBW infants compared to term infants in a cohort study (2016 Israel birth cohort, n = 181,543) using the National Immunization Registry. Vaccinations included Hepatitis B, Diphtheria-Tetanus-acellular Pertussis-IPV-Haemophilus influenzae B, Oral Polio Bivalent, Rotavirus, Pneumococcal Conjugate, Measles-Mumps-Rubella-Varicella and Hepatitis A. Inclusion criteria: (1) born in Israel; (2) having a unique identifier (allowing data matching); and (3) surviving to 24 months. VC at 24 months and timeliness of vaccine doses were evaluated according to infants' birthweight (BW) and gestational age (GA). Preterm infants (GA < 37 weeks) comprised 7.0% (n = 12,264); LBW infants (BW< 2500 g) were 7.7% (n = 13,950); BW was 1500-2499 g in 6.8%, 1000-1499 g in 0.6% and below 1000 g in 0.3%. Compared to normal birthweight (NBW) infants (BW≥2500 g), LBW infants showed delayed initiation of vaccinations. Odds ratio (OR) for delay: DTaP-IPV-Hib 1 OR = 1.26 [95%CI 1.19-1.33]; Rota 1, OR = 1.22 [95%CI 1.16-1.29]. Vaccination delay rates were higher among smaller new-borns (below 1000 g). At 24 months there was no significant difference regarding vaccination status. This national cohort VC analysis focused on preterm/LBW infants. Vaccinating preterm and LBW infants according to the recommended schedule induces protection against life-threatening infectious diseases. Vaccination initiation among LBW infants showed considerable delay. Health practitioners and parents should cooperate to improve timely vaccination initiation.

Immunization in the Neonatal Intensive Care Unit

Premature infants admitted to the neonatal intensive care unit are at risk for severe infections and infectious complications caused by vaccine-preventable diseases. Both maternal and neonatal vaccination prevent such infections and improve outcomes for premature infants. An understanding of vaccine efficacy, safety, and administration recommendations, as well as reasons for vaccine hesitancy among clinicians and caregivers, facilitate strategies for improving vaccination rates for infants in the neonatal intensive care unit. Timely vaccination of premature infants confers important protection and improves vaccination rates during childhood.

Immune Response of Indian Preterm Infants to Pentavalent Vaccine Varies With Component Antigens and Gestational Age

Childhood vaccination plays critical role in protecting infants from several dreaded diseases. Of the global 15 million preterm (PT) infants with compromised immune system born annually, India contributes to >3.5 million. Generation of adequate vaccine-induced immune response needs to be ensured of their protection. Immune response of Indian PT (n = 113) and full-term (FT, n = 80) infants to pentavalent vaccine administered as per the national recommendation was studied. Antibody titers against component antigens of pentavalent vaccine, immune cells profiling (T and B cells, monocytes and dendritic cells) and plasma cytokines were determined pre- and post-vaccination. Additionally, cell-mediated recall immune responses to pentavalent antigens were evaluated after short time antigenic exposure to infant PBMCs. Irrespective of gestational age (GA), all the infants developed adequate antibody response against tetanus, diphtheria, and protective but lower antibody levels for Haemophilus influenzae type-b and hepatitis B in preterm infants. Lower (~74%) protective antibody response to pertussis was independent of gestational age. PT-infants exhibited lower frequencies of CD4 T cells/dendritic cells/monocytes, increased plasma IL-10 levels and lower proliferation of central and effector memory T cells than in term-infants. Proliferative central memory response of FT-infants without anti-pertussis antibodies suggests protection from subsequent infection. Responder/non-responder PT-infants lacked immunological memory and could be infected with Bordetella. For hepatitis B, the recall response was gestational age-dependent and antibody status-independent. Humoral/cellular immune responses of PT-infants were dependent on the type of the immunogen. Preterm infants born before 32 weeks of gestation may need an extra dose of pentavalent vaccine for long lived robust immune response.

The Future of Respiratory Syncytial Virus Disease Prevention and Treatment

Respiratory syncytial virus (RSV) is a major cause of respiratory tract infections in infants, young children, and older or immunocompromised adults. Although aerosolized ribavirin was licensed for RSV treatment on the basis of data demonstrating a reduced need for supplemental oxygen, ribavirin use is limited because of issues with efficacy, safety, and cost. Currently, the treatment of RSV is primarily supportive. New antiviral treatments for RSV are in the early stages of development, but it will be years until any of these may be licensed by the US Food and Drug Administration (FDA). Palivizumab, an RSV monoclonal antibody [immunoprophylaxis (IP)], has demonstrated effectiveness in disease prevention and is the only licensed IP for RSV disease in specific high-risk pediatric populations. Although its efficacy is well established, some challenges that may interfere with its clinical use include cost, need for monthly injections, and changing policy for use by the American Academy of Pediatrics (AAP). Preventing RSV disease would be possible through RSV vaccine development (e.g., live-attenuated, vector-based subunit, or particle-based). Alternatively, new long-acting monoclonal antibodies have demonstrated promising results in early clinical trials. Despite scientific advances, until new agents become available, palivizumab should continue to be used to reduce RSV disease burden in high-risk patients for whom it is indicated.

Vaccination of immune compromised children-an overview for physicians

Immune compromised children are threatened by a higher risk of infections; some of these are preventable by vaccination. Primary care physicians play a fundamental role in optimising vaccination status. In this narrative review, we present the evidence on vaccine safety and immunogenicity in immune compromised children and discuss in which conditions live-attenuated vaccines can possibly be used. Vaccination schedules differ in some of these conditions, including the use of vaccines with higher antigenic contents (e.g. high-dose hepatitis B vaccine), additional vaccine doses (e.g. 2-dose schedule meningococcal vaccine), more frequent booster doses (e.g. life-long pneumococcal vaccine booster), supplementary vaccines (e.g. meningococcal B vaccine) and use of vaccines beyond the age of usual recommendation (e.g. Haemophilus influenza type b vaccine after 5 years of age). Serological monitoring is a useful tool for customizing vaccination schedule in immune compromised children, confirming adequate vaccine response and documenting seroprotection (especially against measles and varicella). Finally, verification of vaccination status of all household members can prevent them being vector of transmission of an infection to the immune compromised children. Conclusion: Intensified information strategies are needed to improve trust, rectify perceived risks and improve vaccine acceptability; primary physicians can play a critical role in the latter. What is Known: • Physician's awareness is key to success, since it repeatedly correlates with higher vaccination rates What is New: • The vaccination status of immunocompromised children is rarely up-to-date • Knowing the latest vaccine recommendations is challenging, as they differ for each medical condition and change periodically • This review summarises the vaccine recommendations for children with compromised immune systems and highlights how paediatricians play a key role in coordinating their application.

The Importance of Hepatitis B Antigen Screening in Pregnancy

In the United States, pregnant women are screened for hepatitis B antigen because of the significant risk of perinatal vertical transmission of hepatitis to the fetus. It is important that the maternal hepatitis B antigen screen is documented in the medical record to ensure appropriate prophylaxis for the neonate. The purpose of this column is to discuss the pathophysiology of hepatitis B, as well as the screening process and prophylaxis for the neonate.

Vaccination of Term and Preterm Infants

Newborns, especially those born preterm, are at high risk for infection. Preterm birth rates appear to be increasing in most countries, with ∼15 million infants born preterm globally each year, corresponding to ∼11% of all deliveries. Importantly, the vulnerability of preterm infants to infection continues beyond the perinatal period, following them throughout childhood and adolescence, highlighting the long-lasting effects of infection on overall health and well-being. Other than access to clean drinking water and proper sewage systems, immunization is the most effective biomedical intervention to reduce early life infection. Nevertheless, a significant proportion of infants discharged on or after 2 months of age from the NICU remains unimmunized or underimmunized at that time. Despite being safe and effective, protective responses to immunization in early life are different from those in older individuals, in part because of the distinct immune system of newborns and young infants. The paradigms of the Bacille Calmette-Guérin, hepatitis B, and polio vaccines, the only immunizations currently routinely administered in the neonatal period, provide evidence that it is feasible to successfully administer vaccines via different routes of delivery; thus, production of sufficient vaccine-induced immunity leads to disease prevention in the newborn. Strategies such as maternal immunization, adjuvantation systems, leveraging trained immunity, and counseling caregivers can be used to enhance vaccine-induced specific and heterologous protection from infection and boost adherence to the recommended immunization schedule.

Safety and immunogenicity of a fully-liquid DTaP-IPV-Hib-HepB vaccine (Vaxelis™) in premature infants

Background: Immune immaturity may put premature infants at increased risk for infections. DTaP-IPV-Hib-HepB vaccine (Vaxelis™), a hexavalent vaccine studied in >6,800 children, has acceptable safety and immunogenicity profiles generally similar to control vaccines. Here we evaluate safety and immunogenicity of DTaP-IPV-Hib-HepB vaccine in premature infants. Methods: Premature infants were identified using prior medical conditions terms "premature baby/delivery" and/or "low birth weight baby". Immunogenicity and safety data were summarized across one Phase II and four Phase III randomized, active-comparator-controlled clinical trials (Protocol 004 in Canada [Control: PENTACEL™]; Protocols 005 and 006 in the US [Control: PENTACEL™]; and Protocols 007 and 008 in the EU [Control: INFANRIX™ hexa]) and one Phase III clinical trial in the UK (PRI01C); no formal statistical comparisons were performed. Results: Overall, 160 infants were considered premature (DTaP-IPV-Hib-HepB = 111 Control = 49). The incidence of adverse events (AEs) for DTaP-IPV-Hib-HepB was comparable between overall and premature populations for all AEs days 1-15 postvaccination (Overall = 96.3%; Premature = 97.3%;), solicited injection-site AEs days 1-5 postvaccination (Overall = 84.1%; Premature = 75.5%), and solicited systemic AEs days 1-5 postvaccination (Overall = 93.7%; Premature = 94.5%). A high percentage of premature infants mounted protective immune responses to antigens contained in DTaP-IPV-Hib-HepB vaccine. Response rates in preterm infants for all antigens (80-99%) were in a similar range to all infants (80-99%) for both DTaP-IPV-Hib-HepB and control vaccines. Conclusions: DTaP-IPV-Hib-HepB vaccine has a low incidence of AEs, an acceptable safety profile, and elicited satisfactory immune responses in premature infants comparable to the overall study population. These findings support vaccination with DTaP-IPV-Hib-HepB vaccine in healthy premature infants.

Immunogenicity of Hepatitis B Vaccine in Preterm or Low Birth Weight Infants: A Meta-Analysis

CONTEXT

The study aims to quantitatively assess the immune response to hepatitis B vaccine in infants born preterm or with low birth weight.

EVIDENCE ACQUISITION

In December 2018, a literature search was conducted in 4 databases without date restrictions. The pooled ORs, mean differences, and their corresponding 95% CIs were calculated with random-effects models using the DerSimonian-Laird estimator. The potential risk of bias of each study was assessed using the Newcastle-Ottawa Scale. The stability and publication bias of the pooled estimates were also evaluated. Analyses were completed in 2019.

EVIDENCE SYNTHESIS

A total of 27 studies including 22,202 infants were eligible for analysis. The studies found that infants born preterm had significantly poorer immune responses to the hepatitis B vaccine. Preterm infants were 1.36 times more likely to exhibit nonresponse to the hepatitis B vaccine (95% CI=1.12, 1.65, p=0.002) compared with their full-term counterparts. The pooled estimates for preterm birth may be subject to a potential publication bias. However, these results were stable, as suggested by the leave-one-out analysis and fail-safe number. The association between low birth weight and impaired immune response to the hepatitis B vaccine was not statistically significant when birth weight was dichotomized at 2,500 g.

CONCLUSIONS

These findings suggest an association between preterm birth and lowered immune responses to hepatitis B vaccine.

Post-marketing surveillance study of the DTaP2-IPV-HB-Hib (Hexyon) vaccine administered in preterm infants in the Apulia region, Italy, in 2017

Recommendations in many countries state that preterm infants (PTIs) should receive the same routine immunization schedule and timing as for full-term births, according to their chronological age. Data regarding hexavalent vaccine safety in PTIs are still limited. We conducted a post-marketing surveillance study of the DTaP2-IPV-HB-Hib vaccine administered to PTIs in Apulia region, Italy. We identified PTIs by selecting the hospital discharge records of infants born between January and June 2017 using the DRG and ICD-9-CM codes for preterm birth, and we matched these data with records included in the regional immunization registry. We analyzed coverage and timeliness of vaccination. To investigate adverse events (AEs) after the first dose, we interviewed via phone the parents of PTIs vaccinated with at least one dose of the DTaP2-IPV-HB-Hib vaccine. At the time of our analysis (31.12.2017), 866/936 (92.5%) PTIs received the first dose of hexavalent vaccine and 539/936 (57.6%) were vaccinated by the third month of age, as recommended; 700/866 (80.8%) received the DTaP2-IPV-HB-Hib vaccine. The parents of 339 PTIs vaccinated with the DTaP2-IPV-HB-Hib vaccine reported local pain as the most common reaction (35.7% of the children). Erythema, swelling, induration and nodule were also reported in about 25% of the children. Systemic adverse events were generally rarer than local reactions. No serious AEs were reported. Our findings showed that more than 40% of PTIs received delayed hexavalent vaccination. This study showed a reassuring safety profile of the vaccine in the preterm population and may be considered as a pilot for further real-world studies.

Precision immunization: a new trend in human vaccination

Vaccination has been one of the major revolutions in the history of human health. Vaccination programs have targeted entire populations such as infants or elderly subjects as a matter of being efficient with time and resources. These general populations are heterogeneous in terms of factors such as ethnicity, health status, and socio-economics. Thus, there have been variations in the safety and effectiveness profiles of certain vaccinations according to current population-wide strategies. As the concept of precision medicine has been raised in recent years, many researchers have suggested that vaccines could be administered more precisely in terms of particular target populations, vaccine formulations, regimens, and dosage levels. This review addresses the concept and framework of precision immunization, summarizes recent and representative clinical trials of among specific populations, mentions important factors to be addressed in customizing vaccinations, and provides suggestions on the establishment of precision immunization with the goal of maximizing the effectiveness of vaccines in general.

Vaccinations in Infants Born Preterm: An Update

Infants born prematurely (before completion of 37 weeks of gestation) are at increased risk of morbidity and mortality due to vaccine preventable diseases, mostly because of their immunological immaturity and failure of transfer of maternal protective antibodies. Despite their great need of being vaccinated, concerns on vaccine safety and efficacy, constitute the main reasons for which vaccinations are often delayed in this group. In this review we summarize the latest evidence on vaccine safety, efficacy and immunogenicity in preterm infants which is similar to full-term infants. Therefore there is no reason for delaying vaccination in this population.

Respiratory syncytial virus hospitalizations in US preterm infants after the 2014 change in immunoprophylaxis guidance by the American Academy of Pediatrics

Palivizumab is the only licensed and effective immunoprophylaxis (IP) available to prevent respiratory syncytial virus (RSV) infection in high-risk infants including infants born at ≤35 weeks' gestational age (wGA). In 2014, the American Academy of Pediatrics stopped recommending IP for otherwise healthy 29-34 wGA infants, stating that their risk of RSV hospitalization (RSVH) was similar to term infants. Recent studies have demonstrated a significant decline in IP use after 2014 that was accompanied by an increased risk of RSVH in 29-34 wGA infants vs term infants. Severity and healthcare utilization of RSVH were high among 29-34 wGA infants. In 2018, the National Perinatal Association developed guidelines advocating IP use in all ≤32 wGA infants and 32-35 wGA infants with additional risk factors. Risk factor predictive models can identify infants who are at risk for RSVH and promote cost-effective use of palivizumab until new methods of RSV prevention become available.

Retrospective Review of Documentation Practices of Hepatitis B Immunoglobulin, Birth Dose, and Vaccination at the Hospital of Birth, in Thai Nationals and Migrants in Northern Thailand

Background

Vaccination remains the mainstay of prevention of hepatitis B virus (HBV) including birth dose and hepatitis B immunoglobulins (HBIGs). National estimates of vaccination coverage exclude migrants. The objective of this study is to investigate documentation practices of HBV-related infant vaccinations in Northern Thailand including migrants.

Methods

This is a retrospective review of hospital records of women who birthed infants in 2015 at Maharaj Nakorn Hospital, Chiang Mai (CM) or on the Thailand-Myanmar border, Tak.

Results

Of 2522 women, 987 were from CM (861 Thai nationals, 126 migrants) and 1535 were from Tak (651 Thai residence and 884 Myanmar residence). In CM, documentation for the birth dose vaccine (999 of 999, 100%) and HBIG was complete. In Tak, documentation was 1441 of 1549 (93%) for birth dose and 26 of 34 (76.5%) for HBIG, with missed opportunities including home delivery, delay in obtaining hepatitis B e-antigen status, and limitations of the records. Expanded Program of Immunization (EPI) documentation of 3 follow-up vaccinations dwindled with subsequent doses and distance, and complete documentation of 3 HBV EPI vaccines at the hospital of birth was low, 41.5% (1056 of 2547), but equitable for Thai or migrant status.

Conclusions

This review provides strong support for excellent documentation of HBIG and birth dose vaccination in urban and rural settings, and in migrants, consistent with Thailand's vaccination policy and practice. Documentation of the 3 HBV EPI at the hospital of birth decreases with sequential doses, especially in families further away. Innovative data linkage is required to prove coverage and identify gaps.

A successful preterm vaccination program in a neonatal unit in a developing country

Background

Although preterm infants are at a greater risk from vaccine preventable diseases, there are frequent delays in vaccine administration with great variability between units. There is little data from developing countries. Groote Schuur Hospital in Cape Town, South Africa starting vaccinating preterm infants from 2014.

Objectives

To determine whether vaccines were given at the correct chronological age and whether there were side effects or logistical problems.

Methods

For a six month period, all infants who were still admitted at 6 weeks of age were included. Date of vaccination and side effects were recorded.

Results

60 infants were included. 57 (95%) received their 6 week vaccines. 68% received the vaccines on time, 10% early and 17% late. Reasons for delay included oxygen dependence and concerns about sepsis. There were no side effects.

Conclusions

It is possible to implement a successful vaccination program for preterm infants in a low resourced setting.

Missed vaccinations and critical care admission: all you may wish to know or rediscover-a narrative review

Most vaccines are so effective that they could lead to the control/elimination of the diseases they target and directly impact on intensive care admissions or complications. This is best illustrated by the use of vaccines against Haemophilus influenzae type b, Streptococcus pneumoniae, zoster, yellow fever, Ebola virus, influenza or measles-but also by third party strategies such as maternal, toddler and care-giver immunization. However, each of these vaccine-induced protection is threatened by insufficient vaccine uptake. Here, we briefly discuss how vaccine hesitancy has led to the resurgence of diseases that were considered as controlled and explore the effect of vaccine-hesitant healthcare workers on nosocomial infections. As intensive care physicians are in charge of polymorbid patients, we briefly summarize the current recommendations for vaccinations in high-risk patients. We finally give some perspective on ongoing research, and discuss how institutional policies and intensive care physicians could play a role in increasing the impact of vaccination, overall and in intensive care units.

The Importance of Vaccinating Children and Pregnant Women against Influenza Virus Infection

Influenza virus infection is responsible for significant morbidity and mortality in the pediatric and pregnant women populations, with deaths frequently caused by severe influenza-associated lower respiratory tract infection and acute respiratory distress syndrome (ARDS). An appropriate immune response requires controlling the viral infection through activation of antiviral defenses, which involves cells of the lung and immune system. High levels of viral infection or high levels of inflammation in the lower airways can contribute to ARDS. Pregnant women and young children, especially those born prematurely, may develop serious complications if infected with influenza virus. Vaccination against influenza will lead to lower infection rates and fewer complications, even if the vaccine is poorly matched to circulating viral strains, with maternal vaccination offering infants protection via antibody transmission through the placenta and breast milk. Despite the health benefits of the influenza vaccine, vaccination rates around the world remain well below targets. Trust in the use of vaccines among the public must be restored in order to increase vaccination rates and decrease the public health burden of influenza.

Timeliness of immunisations in preterm infants in the Netherlands

BACKGROUND

In the Netherlands, preterm infants receive the immunisations at the same chronological age as recommended for term infants without correction for gestational age (GA). The aim of this paper was to describe the timeliness of the routine Dutch national immunisation schedule in preterm infants in their first year of life and to evaluate possible determinants of delay.

METHODS

Preterm infants were prospectively recruited between October 2015 and October 2017 and stratified according to GA (<28, 28-32 and 32-36 weeks). Data from the baseline parental questionnaire, monthly parental questionnaires and medical records were used to determine the immunisation age and proportion of infants timely receiving the first immunisations (between 42 and 63 days). Results were compared between the GA and birth weight (BW) groups. Determinants associated with timeliness of immunisation were studied by multivariate logistic regression analysis.

RESULTS

Timely start of immunisation occurs in 60.5% of preterm infants in the Netherlands. The proportion of infants receiving the first immunisation on time was lowest for the group with GA <28 weeks (37%). The mean age of the first immunisation across all GA groups was 62.7 days (range 33-118) and differed significantly between GA group <28 weeks and the other two GA groups of 28-32 and 32-36 weeks (p < 0.001). Similar results were seen when stratified by BW. Multivariate analysis showed that low socioeconomic status (SES) and prolonged hospitalisation beyond 37 weeks each negatively influenced timeliness of the first immunisation.

CONCLUSION

These findings indicate that start of immunisations was often delayed in prematures and differs for different GA groups, being lowest (37%) in infants <28 weeks GA. Lower SES and prolonged hospital stay beyond 37 weeks GA are important determinants of timeliness. Efforts to improve timeliness should focus most on counselling parents in lower SES.

Outcomes of the national programme on prevention of mother-to-child transmission of hepatitis B virus in China, 2016-2017

BACKGROUND

In addition to providing free hepatitis B vaccine (HBvacc) series to all infants in China since 2005, the national programme on prevention of mother-to-child transmission (PMTCT) of hepatitis B virus (HBV) started providing free hepatitis B immunoglobulin for all new-borns born to hepatitis B surface-antigen (HBsAg) positive mothers in 2010. However, few studies have evaluated the effectiveness of the PMTCT programme. Therefore, we aimed to investigate the outcomes of the programme and identify associated factors.

METHOD

Using a cross-sectional study design, we collected data on 4112 pairs of HBsAg-positive mothers and their children aged 7-22 months in four representative provinces through interviews and medical record review. We tested HBsAg and hepatitis B surface antibody (anti-HBs) of children by enzyme-linked immunosorbent assay at designated maternal and child hospital laboratories. We used logistic regression to analyse factors associated with child HBsAg and anti-HBs positivity.

RESULTS

Thirty-five children were HBsAg positive, indicating the mother-to-child transmission (MTCT) rate was 0.9% (0.6-1.1%). The anti-HBs positive rate was 96.8% (96.3-97.4%). Children receiving HBvacc between 12 and 24 h of birth were 2.9 times more likely to be infected than those vaccinated in less than 12 h (adjusted odds ratio [aOR] = 2.9, 95% confidence interval [CI]: 1.4-6.3, P = 0.01). Maternal hepatitis B e-antigen (HBeAg) positivity was associated with higher MTCT rate (aOR = 79.1, 95% CI: 10.8-580.2, P <  0.001) and lower anti-HBs positive rate (aOR = 0.4, 95% CI: 0.3-0.6, P <  0.001). Children with low birth weight (LBW) were 60% less likely to be anti-HBs positive than those with normal birth weight (aOR = 0.4, 95% CI: 0.2-0.8, P = 0.01).

CONCLUSIONS

The MTCT rate was lower than the 2030 WHO elimination goal, which implies the programme is on track to achieve this target. As earlier HBvacc birth dose (HBvcc-BD) was associated with lower MTCT rate, we suggest that the PMTCT programme work with the Expanded Programme on Immunization (EPI) to modify the current recommendation for early HBvcc-BD to a requirement. Our finding that LBW was associated with lower anti-HBs positivity points to the need for further studies to understand factors associated with these risks and opportunities for program strengthening. The programme needs to ensure providing essential test to identify HBeAg-positive mothers and their infants and provide them with appropriate medical care and follow-up.

Safety and immunogenicity of pneumococcal conjugate vaccines in preterm infants

INTRODUCTION

The introduction of pneumococcal conjugate vaccines (PCVs) in the routine immunization program has resulted in a significant decline in invasive pneumococcal diseases (IPD) around the world. Preterm infants are a special group at a high risk of invasive infection by encapsulated bacteria. However, their slow growth accrual and prolonged hospital stay frequently lead to delays in immunization, which contributes to their risk for severe infections. Areas covered: Authors reviewed the published immunogenicity and safety of the use of PCVs in preterm infants. Expert opinion: PCVs are safe and effective for use in low birth weight and in-hospital preterm infants. Local and systemic reactions are similar for both term and preterm populations. Reports were inconsistent on the risk of apnea, therefore hospitalized extremely premature infants should be kept under observation for at least 48 h after immunization.

Similar relative risks of seizures following measles containing vaccination in children born preterm compared to full-term without previous seizures or seizure-related disorders

BACKGROUND

Febrile seizures are associated with the first dose of measles-containing vaccines and the risk increases with chronologic age during the second year of life. We used the Vaccine Safety Datalink (VSD) to determine if the relative increase in risk of seizures following receipt of measles-containing vaccine differs by gestational age at birth.

METHODS

Children were eligible if they received their first dose of measles-containing vaccine at age 12 through 23 months from January 2003 through September 2015. Children were excluded if they had a history of seizure or conditions strongly related to seizure prior to 12 months of age. Seizures were identified by diagnostic codes in the inpatient or emergency department settings. Using risk-interval analysis, we estimated the incidence rate ratio (IRR) for seizures in the 7 through 10 days (risk period) vs 15 through 42 days (control period) following receipt of measles-containing vaccines in children born preterm (<37 weeks gestation age) and those born full-term (≥37 weeks).

RESULTS

There were 532,375 children (45,343 preterm and 487,032 full-term) who received their first dose of measles-containing vaccine at age 12 through 23 months. The IRRs of febrile seizures 7 through 10 days compared with 15 through 42 days after receipt of measles-containing vaccine were 3.9 (95% CI: 2.5-6.0) in preterm children and 3.2 (2.7-3.7) in full-term children; the ratio of IRRs: was 1.2 (0.76-1.9), p = 0.41. IRRs were also similar across gestational age groups, by vaccine type received (measles-mumps-rubella [MMR] or measles-mumps-rubella-varicella [MMRV]) and age at vaccination (12-15 or 16-23 months).

CONCLUSION

Vaccination with a measles-containing vaccine in the second year of life is associated with a similar relative risk of a first seizure in children born preterm as in those who were born full-term.

Persistence of Vaccine-Induced Immunity in Preschool Children: Effect of Gestational Age

Background

A program of immunization that ensures optimal development of acquired immunity should be carried out in all healthy newborns. The aim of the present study was to verify, at 2.5–3 years after the last dose of basic vaccination, if preschool children who have been delivered preterm and at term differ in their levels of post-vaccination protective antibodies.

Material/Methods

Humoral response was assessed in 352 children (mean age: 5.22±0.34 years) who received a series of obligatory vaccinations in the period from birth to 2.5–3 years of age. Antibodies (in IgG class) against vaccine antigens – diphtheria (D), tetanus (T), pertussis (P), Haemophilus influenzae type b (Hib), poliomyelitis (IPV), measles, mumps, and rubella (MMR) – were measured using ELISA. The level of antibodies against hepatitis B (HBV) was assessed by chemiluminescence.

Results

All children had been immunized according to the Polish National Vaccination Program. The group of 352 children eligible for the study included 46 (13.1%) preschoolers delivered preterm (32–36 weeks of gestation), and 306 (86.9%) born at term (37–42 weeks of gestation). All children maintained seroprotective antibody levels against polioviruses type 1, 2, and 3 (>12 mIU/mL), and against measles antigens (>300 U/mL). No statistically significant differences were found in the proportions of preschoolers born preterm and at term who were seroprotected against other vaccine antigens.

Conclusions

Among preschool children who were immunized according to chronological age, those we were born late preterm do not seem to differ in vaccine-induced immunity from those who were born full-term.

In Search of Factors Negatively Affecting Vaccine Immunity to Pertussis in Preschool Children Before the Administration of the First Booster

INTRODUCTION

The top priority for active immunoprophylaxis of pertussis is the immunisation of infants as they can sometimes develop severe multiple-organ complications.

OBJECTIVES

The aim of the work is the identification of factors negatively affecting vaccine immunity to pertussis in preschool children prior to the administration of the first booster.

PATIENTS AND METHODS

The research was conducted on 352 children from 4.5 to 5.9 years of age who were hospitalised in the University Children's Hospital in Lublin (Poland) from 1 January 2012 to 31 December 2015. The children taking part in the study had been administered all the mandatory vaccines from their birth to the age of 2 or 2.5 years old according to the Polish Immunisation Program 2008⁻2009. The immunoenzymatic method ELISA (enzyme-linked immunosorbent assay) was applied to assess vaccine immunity to tetanus, diphtheria, pertussis, Haemophilus influenzae type b (Hib), poliomyelitis (IPV), mumps, rubella and measles. The level of vaccine antibodies to hepatitis type B was determined chemilumiscently.

RESULTS

The protective antibody titre was not found in 41 (11.65%) children before the administration of the booster. To verify the collective impact of parameters analysed on antibody titre to pertussis, the Generalized Linear Model (GLZ) was used. Gender, type of vaccine, asthma, Hib and mumps antibody titres have been shown to be predictors of vaccine immunity to pertussis.

CONCLUSIONS

Immunomodulation considered on the example of titre of IgG antibody to pertussis can serve as a useful model of the assessment of development of acquired immunity after mandatory vaccinations.

Preterm Children Have Higher Risk Than Full-term Children of Invasive Pneumococcal Disease During the First 2 Years of Life

BACKGROUND

A few previous studies have reported an increased risk of invasive pneumococcal disease (IPD) in children born preterm, but this has not been investigated in a cohort study. The impact of 7-valent pneumococcal conjugate vaccine (PCV7) on IPD incidence rates in preterm children is unknown.

METHODS

Data from the Medical Birth Registry of Norway (2002-2010) were linked to other national registries. In total, 628,138 children were included in our study and followed until 2 years of age. Incidence rate ratios (IRRs) and confidence intervals (CIs) were estimated with Poisson regression.

RESULTS

We identified 411 cases of IPD. We observed higher rates of IPD in preterm than in full-term children for the intervals 0-23, 0-5 and 6-23 months of age, IRRs = 1.83 (95 % CI: 1.36-2.47), 2.95 (95% CI: 1.44-6.06) and 1.69 (95% CI: 1.22-2.34), respectively. The risk for IPD was reduced in the PCV7-period (2007-2010) compared with that of the pre PCV7-period (2002-2005) for children 6-23 months of age, IRRs = 0.20 (95% CI: 0.08-0.53) for preterm children and 0.28 (95% CI: 0.21-0.38) for full-term children, but not for those 0-5 months of age, IRRs = 1.94 (95% CI: 0.48-7.80) and 0.71 (95% CI: 0.38-1.33).

CONCLUSIONS

Preterm children had an increased risk of IPD. After introduction of PCV7, the rate of IPD was reduced among preterm and full-term children from 6 months of age.

From infancy and beyond… ensuring a lifetime of hepatitis B virus (HBV) vaccine-induced immunity

Despite the long-term efficacy and immune persistence observed following HBV vaccination of infants, the need for a booster dose following infant immunization continues to be deliberated. Evidence from HBV booster dose response studies and long-term immunization program reviews are the basis for the recommendation that a vaccine booster is not necessary. However, further studies continue to emerge and highlight the need for standardization among observational studies in order to appropriately compare outcomes. There is an assumption that neonatal and infant (within 12 months of age) vaccine immune responses are equivalent; however, evidence exists for distinct vaccine responses within the first year of life. HBV vaccine programs have evolved over time, particularly regarding the type and dosage of vaccine used. Several universal neonatal immunization programs initially incorporated a 2.5 μg dosage (Recombivax-HB, Merck). This dosage has been shown in multiple long-term studies and meta-analyses to be associated with a lower primary response, decreased antibody persistence over time, and a reduced booster response 10 to 20 years following immunization. Ongoing surveillance of this and other HBV neonatally-vaccinated populations, particularly in low endemic regions, is necessary to understand the impact on long-term protection in order to ensure lifelong protection against hepatitis B infection.

Common Queries About Immunizations in Preterm Infants

Preterm infants are at an increased risk of morbidity and mortality from vaccine-preventable diseases. Despite this, delays in routine immunization of preterm infants are common. Available guidelines clearly state that they should be immunized according to chronological age, irrespective of gestational age and birth weight or current weight. In this article, we try to assuage parental and provider doubts by reviewing data about immunogenicity, safety, and responses to routine immunizations in preterm infants with and without comorbidities. We also look at evidence for other strategies to help protect this fragile population. [Pediatr Ann. 2018;47(4):e147-e153.].

Are pre-terms born timely and right immunized? Results of an Italian cohort study

The aim of this study is to evaluate the vaccination coverage at 24 months of chronological age in a sample of preterm infants discharged by the Neonatal Intensive Care Unit (NICU) of the Bari Policlinico University General Hospital in Italy. The list of infants preterm born discharged during 2013 by the NICU was obtained by hospital database. Vaccination status of each subject at 24 months of chronological age was acquired by the Apulian Regional Vaccination Register (GIAVA). 159 preterm borns were enrolled in this study. 98.1% received the 1st dose of hexavalent vaccine and 98.7% the 1st dose of pneumococcal conjugate vaccine. The 8.8% of hexavalent vaccinations were performed during hospitalization. The percentage of immunized subjects decreased to 91.2% and 87.3% for the 2nd and 3rd dose of hexavalent vaccine and to 90.6% and 86.1% for the 2nd and 3rd dose of pneumococcal conjugate vaccine. Coverage for MMR, MEN C and Varicella vaccines were, respectively 76.4%, 86.0% and 80.9%. Pre-terms received the vaccinations later than the age recommended by public health guidelines. Age at the immunization, for all vaccines, seems to increase for lower gestational age and birth weight and for higher length of hospitalization. This study shows a high risk of vaccine delay among pre-terms born. There is a strong need to improve specific vaccination strategies for this group. Neonatologists might play a key role in informing parents about the vaccination schedule at the moment of NICU discharge and during follow-up, also preparing correct time schedule.

Advances in Pediatric Pharmacology, Therapeutics, and Toxicology

In the United States, the Best Pharmaceuticals for Children Act and the Pediatric Research Equity Act continue to promote clinical trials in pediatric populations across all age ranges. In 2014 and 2015, over 70 changes were made to drug labels with updates on information regarding pediatric populations. Additionally, multiple new therapies have received first-approvals for the treatment of pediatric indications ranging form rare genetic metabolic diseases to oncology. In the European Union, there have been more than 30 new authorizations for medicines used in children and 130 approved pediatric investigation plans. Despite the progress that has been made over the last two years, much work remains to further the development of safe and effective therapies for pediatric patients.