Safety of DTaP–IPV–HIb–HBV hexavalent vaccine in very premature infants

Apnea After 2-Month Vaccinations in Hospitalized Preterm Infants: A Randomized Clinical Trial

Importance

Preterm infants are recommended to receive most vaccinations at the same postnatal age as term infants. Studies have inconsistently observed an increased risk for postvaccination apnea in preterm infants.

Objective

To compare the proportions of hospitalized preterm infants with apnea and other adverse events in the 48 hours after 2-month vaccinations vs after no vaccinations.

Design, Setting, and Participants

This randomized, open-label clinical trial took place at 3 US neonatal intensive care units between August 2018 and October 2021. Infants between 6 and 12 weeks' postnatal age who were born at less than 33 weeks' gestational age and were eligible to receive 2-month vaccines were included.

Intervention

Infants were randomized 1:1 to vaccinated (received vaccines within 12 hours of randomization) or unvaccinated (no vaccines received during the study period) groups. Cardiorespiratory data were collected during the 48 hours after vaccination or randomization (unvaccinated group).

Main Outcomes and Measures

The primary outcome was apnea, defined as a respiration pause greater than 20 seconds or a respiration pause greater than 15 seconds with associated bradycardia less than 80 beats per minute. Other outcomes included the number and duration of apnea episodes, serious adverse events, respiratory support escalation, and receipt of positive pressure ventilation.

Results

Of 223 randomized infants (117 female; median [range] gestational age, 27.6 [23.0-32.9] weeks), 107 (48%) were vaccinated, and 116 (52%) were unvaccinated. For 2 infants in the vaccinated group, the primary outcome was unable to be assessed. The proportion of infants with 1 or more apnea event was 25 of 105 (24%) in the vaccinated group vs 12 of 116 (10%) in the unvaccinated group (adjusted odds ratio, 2.70; 95% CI, 1.27 to 5.73; P = .01). The mean number of apneic episodes did not significantly differ (model point estimate of difference, 0.54; 95% CI, -0.12 to 1.21) between the vaccinated (2.72) and unvaccinated (2.00) groups. The mean duration of apneic episodes did not significantly differ (model point estimate of difference, 4.6; 95% CI, -5.4 to 14.7) between the vaccinated (27.7) and unvaccinated (32.3) groups. No serious adverse events occurred during the 48-hour monitoring period. Other outcomes were not significantly different between groups.

Conclusions and Relevance

In hospitalized preterm infants, the odds of apnea within 48 hours were higher after 2-month vaccinations vs after no vaccinations. The similar number and duration of apneic events and lack of serious adverse events suggest that current vaccination recommendations for hospitalized preterm infants are appropriate. Neonatal clinicians should continue providing evidence-based anticipatory guidance about postvaccination apnea risk.

Trial Registration

ClinicalTrials.gov Identifier: NCT03530124.

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.

Analysis of the positive results and influencing factors of hepatitis B antibody in hospitalized neonates with AgHBs positive mothers

Purpose

To investigate the results of positive antibody to hepatitis surface antigen(anti-HBs)in hospitalized neonates whose mothers were hepatitis B surface antigen (AgHBs) positive and to explore the influencing factors.

Method

The study subjects were hospitalized neonates whose mothers were positive for AgHBs. According to the serological test results of five immune markers of hepatitis B virus (HBV), they were divided into positive for anti-HBs and negative for anti-HBs. Retrospective analysis of relevant factors affecting results of anti-HBs.

Result

269 cases (80.78%) were positive for anti-HBs and 64 cases (19.22%) were negative for anti-HBs. Univariate analysis results: the number of hepatitis B immunoglobulin (HBIG) injections after birth, whether HBIG was injected within 6 h, whether Hepatitis B vaccine (Hep B) was injected within 6 h, whether combined immunization within 12 h, whether Hep B was vaccinated on time after discharge, whether preterm birth, and whether low birth weight infants were statistically significant (P < 0.05). The results of binary logistic regression analysis: HBIG injection time ≤6 h (OR = 0.213), combined immunization time ≤12 h (OR = 0.024) were protective factors; premature infants (OR = 7.175), ALB/GLO (OR = 9.792) and failure to complete three vaccinations on time (OR = 12.659) were risk factors (P < 0.05).

Conclusion

Although China has implemented a national immunization program, vaccination of hospitalized neonates whose mothers are positive for AgHBs has not been effective. Therefore, it is recommended to strengthen training for medical staff and families to ensure that neonates can complete the three doses of vaccination on time after discharge from the hospital and to strengthen follow-up for premature infants.

Timing of the First Dose of the Hepatitis B Vaccine in Preterm Infants

Introduction: The World Health Organization (WHO) recommends all newborn infants receive the first dose of the hepatitis B vaccine within 24 h of birth irrespective of maternal hepatitis B carrier status. However, the physiological immaturity of the immune system in preterm infants may influence the immune responses to the vaccine particularly in the first few days and weeks of life, and adverse events may occur following vaccination that are not observed in infants born at term. Objectives: To review existing published guidelines surrounding timing of the first dose of the hepatitis B vaccine in preterm infants born to hepatitis B surface antigen negative (HBsAg-negative) mothers. Methods: A search was performed for relevant papers and guidelines published between January 2002 and July 2022 on the Ovid MEDLINE and Embase databases and through targeted searches. Two authors independently reviewed the search results to identify relevant sources, which were then analysed and described through narrative synthesis. Results: Twenty-seven relevant papers and guidelines regarding 15 countries and regions were included. Of these, 13.3% of guidelines, which represented 16.8% of the overall population of 4.1 billion people covered by the identified guidelines, recommended a nationwide birth dose of the hepatitis B vaccine to all preterm infants. In 40.0% of guidelines (77.9% of the overall population), the birth dose was only recommended for infants with a birth weight of more than 2000–2200 g. Another 33.3% of countries and regions (covering 4.4% of the population) recommended no universal birth dose for all infants, including preterm infants, whilst 13.3% (1.0% of the population) had guidelines that varied between jurisdictions and hospitals within their country/region. Conclusions: Existing guidelines surrounding the timing of the first dose of the hepatitis B vaccine in preterm infants vary substantially between countries and regions. Further research comparing the immunogenicity and safety of different hepatitis B vaccine schedules is needed to provide concrete evidence to provide guidance regarding the timing of vaccination against hepatitis B in preterm infants.

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.

Five Year Follow Up of Extremely Low Gestational Age Infants after Timely or Delayed Administration of Routine Vaccinations

This study is aimed at detecting the rate of untimely immunization in a large cohort of extremely low gestational age neonates (ELGANs) of the German Neonatal Network (GNN) and at addressing risk factors for delayed vaccination and associated long-term consequences. We performed an observational study of the GNN between 1st January 2010 and 31st December 2019. The immunization status for the hexavalent and pneumococcal immunization was evaluated in n = 8401 preterm infants <29 weeks of gestation. Univariate analysis and logistic/linear regression models were used to identify risk factors for vaccination delay and outcomes at a 5-year follow-up. In our cohort n = 824 (9.8%) ELGANs did not receive a timely first immunization with the hexavalent and pneumococcal vaccine. Risk factors for delayed vaccination were SGA status (18.1% vs. 13.5%; OR 1.3; 95% CI: 1.1–1.7), impaired growth and surrogates for complicated clinical courses (i.e., need for inotropes, necrotizing enterocolitis). At 5 years of age, timely immunized children had a lower risk of bronchitis (episodes within last year: 27.3% vs. 37.7%; OR 0.60, 95% CI: 0.42–0.86) but spirometry measures were unaffected. In conclusion, a significant proportion of ELGANs are untimely immunized, specifically those with increased vulnerability, even though they might particularly benefit from the immune-promoting effects of a timely vaccination.

Update on vaccination of preterm infants: a systematic review about safety and efficacy/effectiveness. Proposal for a position statement by Italian Society of Pediatric Allergology and Immunology jointly with the Italian Society of Neonatology

INTRODUCTION

Preterm infants (PIs) are at increased risk of vaccine-preventable diseases (VPDs). However, delayed vaccination start and low vaccine coverage are still reported. Areas covered: This systematic review includes 37 articles on preterm vaccination published in 2008-2018 in PubMed. Both live attenuated and inactivated vaccines are safe and well tolerated in PIs. Local reactions, apnea, and reactivity changes are the most frequently reported adverse events. Lower gestational age and birth weight, preimmunization apnea, longer use of continuous positive airway pressure (CPAP) are risk factors for apnea. The proportion of PIs who develop protective humoral and cellular immunity is generally similar to full terms although later gestational age is associated with increased antibody IgG concentrations (i.e. against certain pneumococcal serotypes, influenza, hepatitis B virus and poliovirus 1) and increased mononuclear cells proliferation (i.e. after inactivated poliovirus). Expert opinion: PIs can be safely and adequately protected by available vaccines with the same schedule used for full terms. Data at this regard have been retrieved by studies using a 3-dose primary series for pneumococcal and hexavalent vaccines. Further studies are needed regarding the 2 + 1 schedule. Apnea represents a nonspecific stress response in PIs, thus those hospitalized at 2 months should have cardio-respiratory monitoring after their first vaccination.

Clinical and experimental aspects of breathing modulation by inflammation

Neuroinflammation is produced by local or systemic alterations and mediated mainly by glia, affecting the activity of various neural circuits including those involved in breathing rhythm generation and control. Several pathological conditions, such as sudden infant death syndrome, obstructive sleep apnea and asthma exert an inflammatory influence on breathing-related circuits. Consequently breathing (both resting and ventilatory responses to physiological challenges), is affected; e.g., responses to hypoxia and hypercapnia are compromised. Moreover, inflammation can induce long-lasting changes in breathing and affect adaptive plasticity; e.g., hypoxic acclimatization or long-term facilitation. Mediators of the influences of inflammation on breathing are most likely proinflammatory molecules such as cytokines and prostaglandins. The focus of this review is to summarize the available information concerning the modulation of the breathing function by inflammation and the cellular and molecular aspects of this process. I will consider: 1) some clinical and experimental conditions in which inflammation influences breathing; 2) the variety of experimental approaches used to understand this inflammatory modulation; 3) the likely cellular and molecular mechanisms.

Cardio-respiratory Events and Inflammatory Response After Primary Immunization in Preterm Infants < 32 Weeks Gestational Age: A Randomized Controlled Study

BACKGROUND

Inflammation may depress respiration in neonates. This study aimed to establish a link between postimmunization inflammation and cardio-respiratory events (CREs).

METHODS

Randomized double-blind controlled study of infants born < 32 weeks gestation receiving the 2 months vaccine, which comprised diphtheria and tetanus toxoids and acellular pertussis adsorbed combined with inactivated poliomyelitis vaccines and Haemophilus b conjugate and the pneumococcal conjugate 10-valent vaccines. Infants were randomized to ibuprofen treatment or a placebo group (n = 28/group). C-reactive protein (CRP) and prostaglandins E2 (PgE2) levels were assessed before and after immunization. CREs were recorded for 72 hours. Heart rate variability was assessed by polysomnography.

RESULTS

In the placebo group, immunization was associated with significantly increased CRP levels and an increase in CRE (8.6 ± 11.1 before versus 14.0 ± 12.8 after), which did not reach statistical significance (P = 0.08), and no change in PgE2. The increase in CRP was correlated with changes in CRE (r = 0.4: P < 0.05). In the ibuprofen group, immunization significantly increased CRP levels but was not associated with change in CRE (6.7 ± 7.7 before versus 6.8 ± 9.7 after) and PgE2 levels. Comparing the groups, variation in CRE (ΔCRE before versus after immunization) was significantly lower in the ibuprofen group (0.1 ± 7.9 versus 5.4 ± 10.0 ΔCRE; P < 0.05).

CONCLUSION

The first immunization of infants born < 32 weeks was associated with an increase in CRP. Ibuprofen treatment significantly attenuated the variation (Δ) in CRE following first immunization in these infants but the current study could not demonstrate an impact on CRP and PgE2 levels. The impact of anti-inflammatory treatment on antigenicity must be evaluated before their clinical use aiming at reducing CRE after immunization in preterm infants.

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.

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.

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.

Possible predictors of cardiorespiratory events after immunization in preterm neonates

BACKGROUND

The influence of the first immunization on cardiorespiratory (CR) stability in very preterm infants is still a controversial subject.

OBJECTIVES

To describe the changes induced by immunization on heart and respiratory rate variability (HRV-RRV) and to test a potential association between preimmunization profiles and postimmunization CR events.

METHODS

Continuous 72-hour CR recordings and 2.5-hour polysomnographic recordings were performed on very preterm infants immunized after 7 weeks. The results are expressed as medians (interquartile ranges).

RESULTS

Immunization was performed on 31 very preterm infants [28 weeks' gestation (26.9-29), birth weight: 965 g (795-1,105)], and was associated with an increased incidence (p < 0.01) of events lasting more than 10 s: bradycardia <80 bpm [2.2 (1.1-7) vs. 1.8 (1-4)/12 h], desaturation [17.6 (9.4-36.4) vs. 13.9 (7.7-33.8)/12 h] and associated bradycardia-desaturation [IB+D, 4.1 (1.4-7.3) vs. 2.4 (1-4.6)/12 h], with mild changes in HRV and no change in RRV. The changes in IB+D frequency were correlated with preimmunization IB+D frequency (r = 0.44, p < 0.05), HRV spectral parameter low frequency/high frequency ratio (LF/HF, r = 0.55, p < 0.01) and approximate entropy of HRV (r = -0.39, p < 0.05).

CONCLUSION

The increase in CR events after the first immunization in very preterm infants was associated with: (1) sympathetic predominance in heart rate control (high LF/HF ratio), (2) abnormal oversimplification of HRV (low entropy) and (3) persistent respiratory rhythm control immaturity (high IB+D before vaccine).

Frequency of respiratory deterioration after immunisation in preterm infants

AIM

To determine the relationship between the initiation of respiratory support and the first routine immunisation of neonates at 2 months of age during primary hospitalisation.

METHODS

An historical cohort study design was used to study the neonatal factors associated with the initiation of respiratory support within 7 days of immunisation in a cohort of 7629 preterm and term infants admitted to the Neonatal Unit of the Royal Women's Hospital between 2001 and 2008.

RESULTS

The 411 infants who received their first immunisations in hospital were both very preterm and of extremely low birth weight (ELBW, below 1000 g). Twenty-two infants experienced post-immunisation apnoea of sufficient severity to warrant the initiation of either intermittent positive pressure ventilation (two cases) or continuous positive airway pressure (20 cases). Infants exhibiting a respiratory deterioration following immunisation had a higher incidence of previous septicaemia (Odds ratio 2.5, 95% confidence interval 1.0, 6.1; P = 0.04) and received CPAP for a longer period prior to vaccination (P = 0.03).

CONCLUSION

Apnoea following immunisation may be an aetiological factor in the requirement of respiratory support in a small number of preterm, ELBW infants particularly those with significant lung disease and those who have previously experienced septicaemia.

Risk of fever and sepsis evaluations after routine immunizations in the neonatal intensive care unit

OBJECTIVE

Premature infants can experience cardiorespiratory events such as apnea after immunization in the neonatal intensive care unit (NICU). These changes in clinical status may precipitate sepsis evaluations. This study evaluated whether sepsis evaluations are increased after immunizations in the NICU.

STUDY DESIGN

We conducted a retrospective cohort study of infants older than 53 days who were vaccinated in the NICU at the KPMCP (Kaiser Permanente Medical Care Program). Chart reviews were carried out before and after all immunizations were administered and for all sepsis evaluations after age 53 days. The clinical characteristics of infants on the day before receiving a sepsis evaluation were compared between children undergoing post-immunization sepsis evaluations and children undergoing sepsis evaluation at other times. The incidence rate of sepsis evaluations in the post-immunization period was compared with the rate in a control time period not following immunization using Poisson regression.

RESULT

A total of 490 infants met the inclusion criteria. The rate of fever was increased in the 24 h period after vaccination (2.3%, P<0.05). The incidence rate of sepsis evaluations was 40% lower after immunization than during the control period, although this was not statistically significant (P=0.09). Infants undergoing a sepsis evaluation after immunization were more likely to have an apneic, bradycardic or moderate-to-severe cardiorespiratory event in the day before the evaluation than were infants undergoing sepsis evaluations at other times (P<0.05).

CONCLUSION

Despite an increase in fever and cardiorespiratory events after immunization in the NICU, routine vaccination was not associated with increased risk of receiving sepsis evaluations. Providers may be deferring immunizations until infants are clinically stable, or may have a higher threshold for initiating sepsis evaluations after immunization than at other times.

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.

Immunogenicity and reactogenicity of DTPa-HBV-IPV/Hib vaccine as primary and booster vaccination in low-birth-weight premature infants

AIM

To assess suitability of a combined DTPa-HBV-IPV/Hib vaccine (Infanrix hexa) for immunization of low-birth-weight (<2.0 kg) preterm infants, with particular focus on the hepatitis B response.

METHODS

Open-label study in 170 preterm infants receiving primary vaccination at 2, 4 and 6 months of age and booster vaccination at 18-24 months. Enrollment and analysis were stratified in two groups: infants with birth weight between 1.5 kg and 2.0 kg (low birth weight: LBW), infants with BW <1.5 kg (very low birth weight: VLBW).

RESULTS

One month after the three dose primary vaccination, 93.7% and 94.9% of infants in VLBW and LBW groups, respectively, had anti-HBs antibody concentrations > or = 10 mIU/mL. High seroprotection and response rates (92.4-100%) to all vaccine antigens were observed. Those were reinforced (>98%) by booster vaccination for all antigens except for HBs in VLBW children: only 88.7% of those had anti-HBs antibody concentrations > or = 10 mIU/mL, compared with 96.5% of LBW children (difference statistically not significant). The vaccine was well tolerated in both groups of infants.

CONCLUSION

Preterm infants will benefit by the administration of a primary and booster vaccination with DTPa-HBV-IPV/Hib vaccine.

Risk factors for developing apnea after immunization in the neonatal intensive care unit

OBJECTIVES

Among hospitalized NICU infants, preimmunization apnea is a well-recognized predictor of postimmunization apnea. However, predictors for postimmunization apnea among NICU infants without preimmunization apnea have not been investigated.

METHODS

Using a large NICU database in the Northern California Kaiser Permanente Medical Care Program, we abstracted NICU charts of infants who were hospitalized for > or = 53 days and who were also immunized, capturing preimmunization (24 hours before immunization) and postimmunization (48 hours after immunization) events. We assessed factors associated with postimmunization apnea by using multivariate logistic regression.

RESULTS

Of 16,146 infants admitted to the NICU, 557 received > or = 1 vaccine and 497 met the criteria for study entry. All infants with preimmunization apnea (n = 27) and all except 3 infants with postimmunization apnea (n = 65) had gestational ages of < 31 weeks. Multivariate analyses revealed preimmunization apnea as the most important predictor of postimmunization apnea, although higher 12-hour Score for Neonatal Acute Physiology II and age of < 67 days (mean cohort age) were also associated. Multivariate analysis exclusively among infants without preimmunization apnea similarly found elevated Score for Neonatal Acute Physiology II, age of < 67 days, and weight of < 2000 g to be associated with postimmunization apnea. Forty-nine infants without preimmunization apnea and with > or = 1 apnea predictor were discharged within 48 hours after immunization; 2 were subsequently readmitted because of apnea.

CONCLUSIONS

For infants in the NICU without apnea during the 24 hours immediately before immunization, younger age, smaller size, and more severe illness at birth are important predictors of postimmunization apnea.