Hepatitis B vaccination of premature infants: a reassessment of current recommendations for delayed immunization

Bad Liver and a Broken Heart: Hepatitis B in the Newborn

Hepatitis B viral infection is a significant source of morbidity and mortality worldwide. The United States has experienced a precipitous drop in acute hepatitis B infection after the introduction and widespread adoption of recombinant vaccines. Neonates experience significant risk from both vertical and horizontal hepatitis B exposure during a period of immaturity of the innate and adaptive immune systems. Acquisition of hepatitis B virus at or near birth confers the highest lifetime risk of chronic infection and subsequent complications including liver cirrhosis and hepatocellular carcinoma. Pregnant women should be screened for the presence of hepatitis B surface antigen, indicating acute or chronic infection, and, if positive, hepatitis B viral deoxyribonucleic acid, allowing for quantification of viral load. The development of highly effective and safe recombinant vaccines allows partial protection of late preterm and term neonates immediately after birth. Additionally, administration of hepatitis B immune globulin in the setting of suspected or confirmed exposure supplements the immune response and decreases the risk of chronic infection. The optimal timing of vaccination is later in low-birth-weight neonates due to the aforementioned immune system immaturity. Health care providers serving neonates must familiarize themselves with national guidelines regarding hepatitis B vaccination and hepatitis B immune globulin therapy. Understanding the risks of infection and the evidence basis supporting vaccination and immunotherapy will allow providers to educate families and support decision-making, with the potential to eradicate this vaccine-preventable illness in our lifetime.

Lack of relationship between 25-hydoxyvitamin D concentration and a titer of antibodies to hepatitis B surface antigen in children under 12 years of age

The effect of vitamin D levels on the response to the hepatitis B vaccine in childhood and the induced levels of antibodies against the hepatitis B surface antigen (anti-HBs) is not yet well understood. The study aimed to investigate the relationship between age, serum 25-hydroxyvitamin D (25(OH)D) concentration and anti-HBs titer among children under 12 years old. Serum 25(OH)D concentration and anti-HBs titer were determined in 352 healthy Caucasian children with the average age of 4.2 (2.5; 6.3) years. All children were vaccinated with 3 doses of hepatitis B vaccine (Engerix-B, GlaxoSmithKline Pharmaceuticals Limited) in infancy according to the Centers for Disease Control and Prevention recommendations. Only 14.5% of children had an optimal concentration of 25(OH)D ≥ 30 ng/mL and 71.9% children had a seroprotective anti-HBs titer ≥ 10 mIU/mL. Significant negative correlations were found between 25(OH)D, anti-HBs titer and age (r = –0.420, p = 0.000; r = –0.425, p = 0.000, respectively), and a weak positive correlation between 25(OH)D concentration and anti-HBs titer (r = 0.243, p = 0.000). Analysis of six clusters of children demonstrated that age is the main factor affecting anti-HBs titer. One third of children under 12 years of age had nonprotective anti-HBs titer < 10 mIU/mL and around 40% had vitamin D deficiency. We conclude that vitamin D status has no impact on anti-HBs titer in children vaccinated against hepatitis B virus in infancy. Age, so time since the receipt of the last dose of hepatitis B vaccine, is the main factor influencing a decline in anti-HBs titer.

Prevention of vertical transmission of hepatitis B virus infection

Hepatitis B virus (HBV) is the leading cause of chronic viral hepatitis. Annually, almost two million children younger than 5 years acquire the infection, mostly through vertical or horizontal transmission in early life. Vertical transmission of HBV is a high efficacy phenomenon ranging, in the absence of any preventive interventions, from 70% to 90% for hepatitis e antigen positive mothers and from 10% to 40% for hepatitis e antigen-negative mothers. Maternal viraemia is a preeminent risk factor for vertical transmission of HBV. Maternal screening is the first step to prevent vertical transmission of HBV. Hepatitis B passive and active immunoprophylaxis at birth together with antiviral treatment of highly viraemic mothers are the key strategies for global elimination of HBV infection. Strategies are needed to promote implementation of birth-dose vaccination and hepatitis B immunoglobulins in low- and middle-income countries where the prevalence of the infection is at the highest.

Hepatitis B: Immunization and Impact on Natural History and Cancer Incidence

Enhancing host immunity by vaccination to prevent hepatitis B virus (HBV) infection remains the most important strategy for global control of hepatitis B. Currently, 187 countries have in place infant hepatitis B vaccination programs. Hepatitis B surface antigen prevalence has decreased to less than 1% in children after successful implementation of universal HBV vaccination in newborns. The incidence of primary liver cancer in children, adolescents, and young adults has drastically decreased to near zero in birth cohorts receiving hepatitis B vaccination. Elimination of chronic hepatitis B by 2030 is not a mission impossible.

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.

Assessment of the anti-HBs antibody response in Beninese infants following 4 doses of HBV vaccine, including administration at birth, compared to the standard 3 doses regime; a cross-sectional survey

Hepatitis B virus (HBV) infection remains one of the major neglected health issues worldwide. In sub-Saharan Africa (SSA), HBV endemicity is high, with more than 8% of the population being chronic HBV carriers. Recently, WHO recommended that all infants should receive their first dose of the HBV vaccine as soon as possible after birth. Unfortunately, the incorporation of a birth dose of HBV in the expanded programme immunization (EPI) has not occurred in the majority of countries in SSA. From April to September 2017, a cross-sectional survey was conducted in two vaccine units located in southern Benin. We assessed the sustained anti-HBs antibody response in infants induced by a standard scheme of 3 doses of HBV vaccination (6, 10, 14 weeks) in comparison to a scheme of 4 doses with a birth dose included (0, 6, 10, 14 weeks). Blood samples were systematically collected in the first 140 children aged 9 months and their mothers who had consented to participate for the detection of HBs antigen and the quantification of anti-HBs antibodies. The prevalence of HBV infection among infants and mothers was 2.2% and 7.1%, respectively. Infants who received 4 doses of HBV vaccine had a significantly higher level of anti-HBs antibody than those who received 3 doses of vaccine (557.9 UI/L vs. 386.9 UI/L, respectively, P = 0.03). We also showed that the scheme of 4 doses was associated with a significantly higher sustained protective response in comparison to the scheme of 3 doses (aOR 2.49, 95% CI 1.03-6.03, P = 0.04). This result provides further evidence of the importance of administering HBV vaccine at birth, but also highlights the importance for the prevention of vertical transmissions. Additional studies are needed to better establish the cost-effectiveness of such a 4 doses immunization strategy before implementing the HBV vaccination at birth in the EPI.

Japanese original delayed hepatitis B vaccination provides adequate immunogenicity against mother-to-child hepatitis B virus infection in preterm infants: A nationwide survey in Japan

OBJECTIVE

We aimed to evaluate immunogenicity following Japanese original delayed hepatitis B (HB) vaccinations for prevention of mother-to-child HB infection in preterm infants.

METHODS

A nationwide survey in Japan was conducted at certified neonatology facilities in 2014. Eighty-four preterm infants born from a serum hepatitis B surface (HBs) antigen-positive mother were included. We collected data on the following parameters: gestational age, birth weight (BW), age at HB vaccination, age at examination of serum anti-HBs titer, and serum anti-HBs titer. The delayed HB vaccination schedule was 3 doses of HB vaccines at 2, 3 and 5 months of age. A seropositive immunogenic response to HB vaccination was defined as an anti-HBs titer ≥10 mIU/mL. Seropositive rates were calculated in all participants. Four subgroups based on BW were as follows: <1000 g (n = 13), 1000-1499 g (n = 16), 1500-1999 g (n = 26), and ≥2000 g (n = 29).

RESULTS

Among 84 preterm infants who completed the delayed vaccination schedule, 82 (98%) achieved seropositive anti-HBs titer at a median age of 6 months. Seropositive rates of infants <1000 g, 1000-1499 g, 1500-1999 g, and ≥2000 g were 92%, 94%, 100%, and 100%, respectively.

CONCLUSION

The Japanese original delayed HB vaccinations achieved sufficient seropositive rates in preterm infants and provide immunogenicity against mother-to-child HB infection.

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.

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.].

Immunization of preterm infants with GSK's hexavalent combined diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-Haemophilus influenzae type b conjugate vaccine: A review of safety and immunogenicity

BACKGROUND

Infants with history of prematurity (<37 weeks gestation) and low birth weight (LBW, <2500 g) are at high risk of infection due to functional immaturity of normal physical and immunological defense mechanisms. Despite current recommendations that infants with history of prematurity/LBW should receive routine immunization according to the same schedule and chronological age as full-term infants, immunization is often delayed.

METHODS

Here we summarize 10 clinical studies and 15 years of post-marketing safety surveillance of GSK's hexavalent vaccine (DTPa-HBV-IPV/Hib), a combined diphtheria-tetanus-acellular-pertussis-hepatitis-B-inactivated-poliovirus-Haemophilus influenzae-type-b (Hib) conjugate vaccine, when administered alone, or co-administered with pneumococcal conjugate, rotavirus, and meningococcal vaccines and respiratory syncytial virus IgG to infants with history of prematurity/LBW in clinical trials.

RESULTS

At least 92.5% of infants with history of prematurity/LBW as young as 24 weeks gestation in clinical studies were seropositive to all vaccine antigens after 3-dose primary vaccination with GSK's hexavalent DTPa-HBV-IPV/Hib vaccine, with robust immune responses to booster vaccination. Seropositivity rates and antibody concentrations to hepatitis B and Hib appeared lower in infants with history of prematurity/LBW than term infants. Between 13-30% of medically stable infants with history of prematurity developed apnea after vaccination with GSK's hexavalent DTPa-HBV-IPV/Hib vaccine; usually after dose 1. The occurrence of post-immunization cardiorespiratory events appears to be influenced by the severity of any underlying neonatal condition. Most cardiorespiratory events resolve spontaneously or require minimal intervention. GSK's hexavalent DTPa-HBV-IPV/Hib vaccine was well tolerated in co-administration regimens.

CONCLUSION

GSK's hexavalent DTPa-HBV-IPV/Hib vaccine alone or co-administered with other pediatric vaccines has a clinically acceptable safety and immunogenicity profile when used in infants with history of prematurity/LBW for primary and booster vaccination. Additional studies are needed in very premature and very LBW infants. However, currently available data support using GSK's hexavalent DTPa-HBV-IPV/Hib vaccine to immunize infants with history of prematurity/LBW according to chronological age.

Plasma cell and serum antibody responses to influenza vaccine in preterm and full-term infants

BACKGROUND

Preterm (PT) infants are at greater risk for severe influenza infection and experience decrements in long-term antibody responses to vaccines. This may related to defects in antibody secreting cell (ASC) generation.

OBJECTIVE

To investigate the relationships among the frequencies of influenza-specific antibody secreting cells, ASC numbers and subsets, and antibody responses to influenza vaccines (IV) among PT and full-term (FT) infants.

DESIGN/METHODS

We enrolled 11 former PT (≤32weeks' gestation, ≤1500 g' birth weight) and 11FT infants, 6-17months of age, receiving their first influenza immunizations. Infants received two doses of inactivated trivalent (T)IV or quadrivalent (Q)IV during the 2012-2013 and 2013-2014 influenza seasons, respectively, at 0 and 28days, and blood was drawn at 0, 10, 35, and 56days and 9months. Vaccine-specific antibody was measured by hemagglutination inhibition (HAI) at 0 and 56days and 9months, vaccine-specific ASC numbers by enzyme linked immunospot (ELISPOT) at 10 and 35days, and ASC subsets by flow cytometry at 0, 10 and 35days.

RESULTS

PT infants had post-vaccine HAI titers to all 4 vaccine strains at least equal to FT infants at 56days and 9months after beginning immunization. Influenza-specific ASC ELISPOT responses at 35days were higher among PT than FT infants (median 100 v. 30 per 10⁶ PBMC, p=0.04). ASC numbers at 35days were positively correlated with serum HAI titers at 56days (ρ=0.50-0.80). There were no statistical differences between PT and FT infants in the frequency of five ASC subsets and no specific ASC subset correlated with durability of serum antibody titers.

CONCLUSIONS

Influenza-specific ASC numbers in both FT and PT infants correlated with peak antibody titers, but ASC subsets did not correlate with durability of antibody response.

Assessment of Immunization to Hepatitis B Vaccine among Children under Five Years in Rural Areas of Taiz, Yemen

Background. Hepatitis B virus (HBV) infection poses a major health problem worldwide. approximately 1 million deaths annually due to cirrhosis and hepatocellular carcinoma. Objectives. This study was conducted to determine the coverage rate of HBV vaccine and assess the vaccine protective response among children under five years old in rural areas of Yemen. Methods. A cross-sectional study was conducted from January to December 2015 in four districts of countryside Yemen. The target population was children aged from 6 to 59 months. 227 children were enrolled in the study. Questionnaire was used to collect of data. Serum samples were tested for anti-HBs antibodies by enzyme linked immunosorbent assay (ELISA). Anti-HBs level ≥ 10 IU/L was considered a protective response to the vaccine. Results. The coverage rate of HBV vaccine among children was 87.3%. A total of 143 (72.2%) children responded to the vaccine with anti-HBs level ≥ 10 IU/L, while 55 (27.8%) of the children had nonprotective anti-HBs levels of <10 IU/L (P = 0.003). Conclusion. This study revealed a good coverage rate of HBV vaccine in rural areas but the protective rate against HBV infection was moderate. A considerable proportion of vaccinated children should be considered for either revaccination or booster doses.

Quantitative maternal hepatitis B surface antigen predicts maternally transmitted hepatitis B virus infection

Despite immunoprophylaxis, hepatitis B virus (HBV) transmission in highly viremic mothers remains a global health issue. Using quantitative maternal surface antigen (HBsAg) to predict HBV infection in infants has not been investigated. We enrolled 526 mother-infant pairs with positive maternal HBsAg under current immunoprophylaxis. Maternal viral load and quantitative HBsAg were measured in the peripartum period. Infant HBsAg seropositivity for more than 6 months was defined as chronic infection. Rates of chronic infection in infants at various maternal HBsAg levels were estimated using a multivariate logistic regression model. Results showed that maternal HBsAg was positively correlated with maternal viral load (r = 0.69; P < 0.001) and accurately predicted maternal viral load above 6, 7, and 8 log₁₀ IU/mL with an area under the receiver operating characteristic curve (AUC) of 0.97, 0.98, and 0.95. Nineteen infants were chronically infected. After adjustment for the other risk factor, maternal HBsAg level was significantly associated with risk of infection (adjusted odds ratio for each log₁₀ IU/mL increase, 15.02; 95% confidence interval [CI], 3.89-57.94; P < 0.001). The AUC for predicting infection by quantitative maternal HBsAg was comparable to that by maternal viral load (0.89 vs. 0.87; P = 0.459). Estimated rates of infection at maternal HBsAg levels of 4, 4.5, and 5 log₁₀ IU/mL were 2.4% (95% CI, 0.1-4.6; P = 0.04), 8.6% (95% CI, 4.5-12.7; P < 0.001), and 26.4% (95% CI, 12.6-40.2; P < 0.001).

CONCLUSION

Quantitative maternal HBsAg predicts infection in infants as well as maternal viral load does. Antiviral therapy may be considered in pregnant women with an HBsAg level above 4-4.5 log₁₀ IU/mL to interrupt mother-to-infant transmission. (Hepatology 2016;64:1451-1461).

Immunization of preterm infants

Vaccinations of premature infants are often delayed despite being at an increased risk of contracting vaccine preventable diseases. This article reviews the current knowledge on the immune response to widely used vaccines, on the protection derived from routine immunization and on vaccine safety and tolerability in a population of preterm infants. Available data evaluating the immune response of preterm infants support early immunization without correction for gestational age. For a number of antigens, the antibody response to initial doses of vaccines may be lower than that of term infants, but protective concentrations are often achieved and memory successfully induced. Vaccines are immunogenic, safe and well tolerated in preterm infants. Preterm infants should be vaccinated using the same schedules as those usually recommended for full-term infants, with the exception of the hepatitis B vaccine, where additional doses should be administered in infants receiving the first dose during the first days of life if they weighed less than 2000 g because of a documented reduced immune response.

Protective effect of an improved immunization practice of mother-to-infant transmission of hepatitis B virus and risk factors associated with immunoprophylaxis failure

Although routine immunoprophylaxis has been known to reduce hepatitis B virus (HBV) transmission, immunoprophylaxis failure still occurs. The study aimed to investigate the protective efficacy of an improved immunoprophylaxis protocol to prevent mother-to-infant transmission of HBV and to explore the potential risk factors associated with immunoprophylaxis failure and low antibody response.A prospective observational cohort study was conducted from July 2012 to April 2015. A total of 863 HBsAg-positive mothers and their 871 infants (8 pairs of twins) were included in the study. Two different hepatitis B vaccine doses (20 or 10 μg) were administered to the infants based on the hepatitis B e-antigen (HBeAg) status of their mothers. Simultaneously, hepatitis B immunoglobulin (HBIG) was administered to the infants. Initial injections of HBIG and the hepatitis vaccine were given within 2 hours after birth. Rates of HBV infections among the infants were evaluated at 7 months of age. Factors associated with immunoprophylaxis failure and low responses to vaccination were analyzed by unconditional logistic regression..At 7 months of age, no immunoprophylaxis failure was observed in the 565 infants born to HBeAg-negative mothers. Among the 306 infants born to HBeAg-positive mothers, immunoprophylaxis failed in 16 infants (5.2%) of the infants and they were found to be HBsAg-positive. Further analysis showed that HBV DNA levels ≥10 IU/mL [odds ratio (OR) = 4.53, 95% confidence interval (95% CI): 1.19-17.34], delayed vaccination (OR = 4.14, 95% CI: 1.00-17.18), and inadequate initial injections (OR = 7.69, 95% CI: 1.71-34.59) were independently associated with immunoprophylaxis failure. Adequate titers of antibody to HBsAg (anti-HBs, ≥100 mIU/mL) were present in 96.5% of immunoprophylaxis-successful infants. For full-term infants, birth weights <3000 g were correlated with low immune responses to vaccination.This improved immunoprophylaxis protocol is effective in preventing perinatal transmission of HBV. Among infants with HBeAg-positive mothers, high HBV viral loads and inadequate and delayed initial injections were associated with immunoprophylaxis failure. The majority of the infants in our study produced adequate levels of protective anti-HBs titers after immunoprophylaxis. Additional efforts to further reduce perinatal transmission should be considered, especially for HBeAg-positive mothers.

Hepatitis B Postexposure Prophylaxis in Preterm and Low-Birth-Weight Infants

Objective Recommendations for immunoprophylaxis in low-birth-weight (LBW) infants born to hepatitis B surface antigen (HBsAg)-positive mothers vary. We successfully immunized an HBsAg-exposed infant (birth weight: 400 g) and performed a literature review on the outcome of postexposure immunoprophylaxis in HBsAg-exposed preterm and LBW infants. Methods By use of PubMed we identified articles relevant to the topic. Studies were included if the intended vaccine schedule was completed and follow-up data were reported. Results Antibody response was reported in 31 LBW infants (birth weight < 2,500 g) and 49 infants with gestational age of < 38 weeks. Low anti-HBs antibody levels (< 100 IU/L) were found in 9 (29%) of the 31 LBW infants. Overall, 2 of 20 (10%) preterm infants and 2 of 17 (12%) LBW were HBsAg-positive on follow-up. In one study, none of the 26 exposed very LBW infants became infected. Conclusion Due to heterogeneity in immunization schedules, lack of information on transmission rates, and the small number of included subjects, no firm conclusions can be drawn regarding the optimal postexposure prophylaxis in LBW infants. We propose that active and passive immunization at birth should be completed by three further active doses (0-1-2-12 month schedule) until further prospective studies are available.

Zinc supplementation fails to increase the immunogenicity of oral poliovirus vaccine: a randomized controlled trial

BACKGROUND

Polio eradication remains a challenge in Pakistan and the causes for the failure to eradicate poliomyelitis are complex. Undernutrition and micronutrient deficiencies, especially zinc deficiency, are major public health problems in Pakistan and could potentially affect the response to enteric vaccines, including oral poliovirus vaccine (OPV).

OBJECTIVE

To assess the impact of zinc supplementation among infants on immune response to oral poliovirus vaccine (OPV).

METHODS

A double-blind, randomized placebo-controlled trial was conducted in newborns (aged 0-14 days). Subjects were assigned to either receive 10mg of zinc or placebo supplementation daily for 18 weeks. Both groups received OPV doses at birth, at 6 weeks, 10 weeks and 14 weeks. Data was collected on prior immunization status, diarrheal episodes, breastfeeding practices and anthropometric measurements at recruitment and at 6 and 18 weeks. Blood samples were similarly collected to determine the antibody response to OPV and for micronutrient analysis. Logistic regression was used to determine the relationship between seroconversion and zinc status.

RESULTS

Overall, 404 subjects were recruited. At recruitment, seropositivity was already high for poliovirus (PV) serotype 1 (zinc: 91.1%; control: 90.5%) and PV2 (90.0%; 92.7%), with lower estimates for PV3 (70.0%; 64.8%). By week 18, the proportion of subjects with measured zinc levels in the normal range (i.e. ≥60 μg/dL) was significantly greater in the intervention group compared to the control group (71.9%; 27.4%; p<0.001). No significant difference in seroconversion was demonstrated between the groups for PV1, PV2, or PV3.

CONCLUSIONS

There was no effect of zinc supplementation on OPV immunogenicity. These conclusions were confirmed when restricting the analysis to those with measured higher zinc levels.

Weight-based policy of hepatitis B vaccination in very low birth weight infants in Taiwan: a retrospective cross-sectional study

Background

The current recommendation of giving the first dose of hepatitis B vaccine to very low birth weight (VLBW) infants at 30 days of chronologic age usually is not practical, because most VLBW infants are not medically stable at that age. We use an alternative body-weight-based protocol, and evaluate its efficacy in an endemic area under a universal immunization program.

Methods

The immunogenicity of the current hepatitis B vaccination strategy in 155 VLBW preterm infants was evaluated at age 2 to 13 years, with parental consent. All of the infants were born between 1995 and 2006, and received their first dose of hepatitis B vaccine when they reached 2,000–2,200 g, irrespective of chronological age. Hepatitis B immunoglobulin (HBIG) was given at birth to infants born to HBsAg(+)/HBeAg(+) mothers.

Results

All 155 of the recruited children were HBsAg and anti-HBc negative. The anti-HBs seropositivity rate (geometric mean titer) was 84.1% (146.5 mIU/mL) for children under 3 years, 73.5% (68.8 mIU/mL) for 4- to 7-year-olds, 27.7% (55.4 mIU/mL) for 8- to 11-year-olds and 20% (6.0 mIU/mL) for children ≥12 years of age. More than 90% of these children received the first vaccination after 30 days of age, half (51%) at 60 to 90 days, and 29 children (18.6%) after 90 days of age. Of the 26 infants born to HBsAg(+) mothers, 6/6 infants of HBeAg(+) mothers received HBIG at birth, and 12/20 infants of HBeAg(−) mothers received HBIG. None of the 26 infants became infected.

Conclusions

Delaying hepatitis B vaccinations in VLBW preterm infants until they reach a weight of 2,000 g, with the administration of HBIG at birth for infants of HBsAg(+) mothers provided adequate immunogenicity and protection in a highly endemic area. Weight-based policy of hepatitis B vaccination is an effective and practical alternative strategy for VLBW infants.

Hepatitis B vaccine response among infants born to hepatitis B surface antigen-positive women

PURPOSE

Annually, an estimated 25,000 infants are born to hepatitis B surface antigen (HBsAg)-positive women in the United States. Hepatitis B (HepB) vaccine and hepatitis B immune globulin (HBIG) are recommended at birth, followed by completion of vaccine series and post-vaccination serologic testing (PVST). In a large cohort of infants born to HBsAg-positive women, factors influencing vaccine response were evaluated.

METHODS

Data were from HBsAg-negative infants born to HBsAg-positive women in the Enhanced Perinatal Hepatitis B Prevention Program (EPHBPP) from 2008 to 2013. Vaccine non-responders were defined as infants with antibody to hepatitis B surface antigen (anti-HBs) <10mIU/mL at PVST after receiving ≥3 vaccine doses. Multivariable analyses modeled statistically significant predictor variables associated with non-response.

RESULTS

A total of 17,951 maternal-infant pairs were enrolled; 8654 HBsAg-negative infants born to HBsAg-positive mothers received ≥3 doses of vaccine with anti-HBs results. 8199 (94.7%) infants responded to a primary HepB series; 199 (94.8%) to a second series. Factors associated with anti-HBs <10mIU/mL included gestational age <37 weeks, vaccine birth dose >12h after birth, timing of final vaccine dose <6 months after birth, receipt of 3 vs. 4 vaccine doses, and PVST interval >6 months from final vaccine dose in bivariate analysis. PVST interval >6 months from final vaccine dose (OR=2.7, CI=2.0, 3.6) was significantly associated with anti-HBs <10mIU/mL; the proportion increased from 2% at 1-2 months to 21.6% at 15-16 months after the final dose. Receipt of a 4th dose improved the response rate (OR=0.5, CI=0.3, 0.8).

CONCLUSIONS

Ninety-five percent of a large cohort of uninfected infants born to HBsAg-positive mothers in the United States responded to primary HepB vaccine series. The proportion of infants with anti-HBs <10mIU/mL increased with longer interval between the final vaccine dose and PVST. Optimal timing of PVST is within 1-2 months of final vaccine dose to avoid unnecessary revaccination.

Prevention of mother to child transmission of hepatitis B infection

The likelihood of developing chronic hepatitis B infection and its complications is most when infection is transmitted vertically. Awareness of the current recommendations for managing babies of mothers who are hepatitis B carriers is not universal, resulting in failure of follow up, despite the serious long term implications, including development of hepatic carcinoma. We review the current guidelines of managing babies born to mothers who are hepatitis B carriers.

Predictors of Poor Response After Primary Immunization of Hepatitis B Vaccines for Infants and Antibody Seroprotection of Booster in a Metropolis of China

To evaluate proportion and predictors of poor response in infants and appraise booster seroprotection, we surveyed 2047 infants in Shanghai and detected antibody to hepatitis B (HB) surface antigen (anti-HBs). Poor responders were randomized into 2 groups, given booster with 5 µg and 10 µg hepatitis B vaccine (HepB), respectively. Proportion of infants with titer <10 mIU/mL and 10 to 99 mIU/mL was 1.86% and 15.14%, respectively. Multivariate logistic regression suggested infants of male, aged 13 to 18 months, premature, administered with 5 µg HepB or mother positive for HB surface antigen (HBsAg) and HBe antigen (HBeAg) would more likely develop worse response. Difference of geometric mean concentration between the first and full booster was not statistically significant both for 5 µg and for 10 µg HepB groups. The seroprotective rate were higher for infants with 10 µg HepB than those with 5 µg HepB ( P > .05). Therefore, it is concluded that booster for poor vaccinees with 10 µg HepB could achieve satisfactory seroprotection.

Mother-to-infant transmission of hepatitis B virus infection: significance of maternal viral load and strategies for intervention

BACKGROUND & AIMS

Immunoprophylaxis reduces but does not completely eradicate hepatitis B virus (HBV) transmission. This prospective study aims at assessing the rate and risk factors of maternally transmitted HBV infection.

METHODS

We enrolled 303 mother-infant pairs with positive maternal hepatitis B surface antigen (HBsAg) under current immunization program. Maternal viral load was determined by a real-time PCR-based assay. The children were tested for HBsAg at 4-8 months and/or 1-3 years of age. Rates of HBV infection were estimated using a multivariate logistic regression model.

RESULTS

HBeAg-positive mothers (81/303, 26.7%) had higher viral loads than HBeAg-negative mothers (7.4 ± 1.9 vs. 2.7 ± 1.4 log10 copies/ml, p<0.0001). Ten children, born to HBeAg-positive mothers with high viral load (median, 8.4; range, 6.5-9.5 log₁₀ copies/ml), were chronically infected. After adjustment for maternal age, birth type, factors related to maternal-fetal hemorrhage, gestational age, infant gender, birth weight, timeliness of vaccination, and feeding practice, maternal viral load was significantly associated with risk of infection (adjusted odds ratio for each log₁₀ copy/ml increase, 3.49; 95% confidence interval (CI), 1.63-7.48; p=0.001). The predictive rates of infection at maternal viral load levels of 7, 8, and 9 log₁₀ copies/ml were 6.6% (95% CI, 0.5-12.6%; p=0.033), 14.6% (95% CI, 5.6-23.6%; p=0.001), and 27.7% (95% CI, 13.1-42.4%; p<0.001), respectively.

CONCLUSIONS

Additional strategies to further reduce transmission should be considered in mothers with a viral load above 7-8 log₁₀ copies/ml.

Seroprotection after recombinant hepatitis B vaccination among newborn infants: a review

INTRODUCTION

Hepatitis B vaccination starting at birth provides a safety net for infants exposed to hepatitis B virus (HBV) during delivery or in early life. Hepatitis B vaccine is recommended in the United States for infants prior to birthing facility discharge, and within the first 12h of life for infants born to hepatitis B surface antigen (HBsAg)-positive mothers. We performed a literature review and summarized the response to recombinant hepatitis B vaccine among infants.

METHODS

Studies published between 1987 and 2011 assessing seroprotection from recombinant hepatitis B vaccine starting within the first 30 days of life were eligible. Seroprotection was defined using an antibody to hepatitis B surface antigen (anti-HBs) threshold of 10mIU/mL at series completion. Infant seroprotection was compared in trial arms varying by maternal hepatitis B antigen status (e antigen [HBeAg], HBsAg), hepatitis B immune globulin (HBIG) administration, birth weight, vaccine dosage, schedule, and age at first dose.

RESULTS

Forty-three studies were included. The median seroprotection proportion overall was 98% (range 52%, 100%). The final median seroprotection proportions did not vary appreciably by maternal HBsAg status, HBIG administration, or schedule. Higher compared to lower dosage resulted in earlier increases in anti-HBs but not in final seroprotection proportions. Infants with birth weights <2000g compared to ≥2000g had lower median seroprotection proportions (93% and 98%, respectively). Median seroprotection proportions were also lower when infants with birth weights <2000g were vaccinated at 0-3 days of age compared to 1 month of age or older (68% versus 95%, respectively).

CONCLUSION

High levels of protection from recombinant hepatitis B vaccine are achieved in term infants vaccinated at birth, effectively preventing transmission of HBV and resultant morbidity and mortality. Implications, if any, for long-term protection are unknown for differences in responses among infants vaccinated at birth compared to ages older than 1 month.

Revaccination of non- and low- responders after a standard three dose hepatitis B vaccine schedule

BACKGROUND

Guangdong province of China is HBV high endemicity and 1.6 million neonates are administrated 5 μg yeast recombinant anti-HBV vaccine each year. But few studies are performed to evaluate the immunogenicity and revaccination effect on non- and low- responders.

METHODS

2,199 children were administered intramuscularly with 5 μg vaccine at 0, 1 and 6 mo after birth. A 3 ml blood sample was drawn from each infant 1 mo after the third dose for determination of anti-HBs level. Three additional doses (10 μg each) were given to non- and low- responders.

RESULTS

Of 1,814 subjects, 3.1% were non-responders (anti-HBs titer < 10 mIUml (-1) ) and 28.9% were low-responders (anti-HBs ≥ 10 mIUml (-1) and < 100 mIUml (-1) ). Low birth weight (LBW) was a risk factor for non- and low- responders (RR = 1.6, 95%CI = 1.2-2.0). After revaccination, of the 34 non-responders, 14.7% became low-responders and 85.3% became responders. Of the 74 low-responders, 21.6% remained at the same level and 78.4% shifted into responder category.

CONCLUSIONS

Based on the lower responding rate after the primary immunization cycle and the higher responding rate after the additional cycle, measurement of anti-HBs level should be considered for people who had been immunized with three-dose 5 μg HB vaccine in Guangdong, especially for specific populations including LBW infants, healthcare workers, and patients with immunodeficiency disorders. An amount of 10 μg vaccine should be revaccinated to any non- and low- responders to provide adequate seroprotection.

Immunization in special populations

In summary, immunizations in special populations require understanding the underlying disease and how it might affect the immune system's ability to mount an antibody response to vaccines or predispose certain patient populations to developing certain serious infections. There is still a great need for research on the optimal timing of vaccines after transplants, how to assess protection and development of a protective antibody response after immunization, and whether certain groups (eg, HIV) need to be revaccinated after a certain amount of time if their antibody levels decline. In addition, there are limited data on efficacy of the newer vaccines in these special patient populations, which also requires further investigation.

Association of Thymectomy With Infection Following Congenital Heart Surgery

Background: Congenital absence of the thymus can lead to profound immunodeficiency, suggesting that thymic function during fetal development is essential to normal lymphocyte development. How vital the thymus after birth is to human immune competence and regulation is not known. Routine thymectomy, especially at an early age, may influence immunity, and therefore the risk of infection, autoimmunity, or malignancy. Methods: A retrospective review of cardiac surgery patients followed at Seattle Children’s Hospital was performed. The primary outcome was rate of serious infections requiring hospitalization. Secondary analyses included age, type of infection, cardiac diagnosis, surgical procedure, and comorbidities. Results: Patients fell into 2 groups: 60 with complete thymectomy and 35 with partial or no thymectomy. There was no statistical difference between groups in the overall prevalence of serious infections (16.7% vs 17.2%, P = 1.0). There was a nonsignificant trend toward reduced time between surgery and onset of first infection in patients in the total thymectomy group versus those without thymectomy (1.7 years vs 4.6 years, P = .07). Total thymectomy before 6 months of age also tended to increase infection rate, but the effect was not significant (0.09/year vs 0.02, P = .14). Gastroesophageal reflux in patients with total thymectomy increased the risk of infection ( P = .013), suggesting a cumulative effect. Conclusions: Though infections occurred frequently in the childhood cardiac surgery population, total thymectomy was not associated with increased risk of serious infection. Comorbid conditions may be more important contributing factors increasing the risk of infection in this complex and vulnerable population.

Heptavalent pneumococcal conjugate vaccine immunogenicity in very-low-birth-weight, premature infants

BACKGROUND

The heptavalent pneumococcal CRM197 conjugate vaccine (PCV-7) has been incompletely studied in very-low-birth-weight (< or =1500 g) infants.

OBJECTIVE

To assess PCV-7 immunogenicity in very-low-birth-weight, premature infants. We hypothesized that the frequency of postvaccine antibody concentrations > or =0.15 microg/mL would vary directly with birth weight.

METHODS

This was a multicenter observational study. Infants 401 to 1500 g birth weight and <32 0/7 weeks gestation, stratified by birth weight, were enrolled from 9 National Institute of Child Health and Human Development Neonatal Research Network centers. Infants received PCV-7 at 2, 4, and 6 months after birth and had blood drawn 4 to 6 weeks following the third dose. Antibodies against the 7 vaccine serotypes were measured by enzyme-linked immunosorbent assay.

RESULTS

Of 369 enrolled infants, 244 completed their primary vaccine series by 8 months and had serum obtained. Subjects were 27.8 +/- 2.2 (mean +/- standard deviation) weeks gestation and 1008 +/- 282 g birth weight. Twenty-six percent had bronchopulmonary dysplasia and 16% had received postnatal glucocorticoids. Infants 1001 to 1500 g birth weight were more likely than those 401 to 1000 g to achieve antibody concentrations > or =0.15 microg/mL against the least 2 immunogenic serotypes (6B: 96% vs. 85%, P = 0.003 and 23F: 97% vs. 88%, P = 0.009). In multiple logistic regression analysis, lower birth weight, postnatal glucocorticoid use, lower weight at blood draw, and Caucasian race were each independently associated with antibody concentrations <0.35 microg/mL against serotypes 6B and/or 23F.

CONCLUSIONS

When compared with larger premature infants, infants weighing < or =1000 g at birth have similar antibody responses to most, but not all, PCV-7 vaccine serotypes.

Hepatitis B response of premature infants after primary and booster immunisation with a diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/haemophilus influenzae type B vaccine

A range of schedules are recommended for hepatitis B vaccination of premature infants. This open-label study (217744/083) compared the immune response of premature (N = 94) and full-term infants (N = 92) to hepatitis B antigen following primary administration of hexavalent DTPa-HBV-IPV/Hib vaccine at 2–4–6 months and a booster dose at 18 months. Anti-HBsAg antibodies were determined before and one month after primary and booster doses. There were no significant differences in postprimary seroprotection rates (anti-HBsAg >10 mIU/mL; preterm 93.4%; full-term 95.2%) or geometric mean concentrations (634 versus 867 mIU/ml), and neither appeared to be related to gestational length or birth weight. Prebooster seroprotection rates were 75 and 80.6%, respectively. Six premature infants did not respond to primary and booster doses. Primary and booster vaccinations with DTPa-HBV-IPV/Hib elicit satisfactory anti-HBsAg responses in preterm infants, which are not influenced by gestational age or birth weight. This schedule and vaccine will greatly facilitate the immunisation of premature infants.

Low hepatitis B immunogenicity of a hexavalent vaccine widely used in Germany: results of the German Health Survey for Children and Adolescents, 2003–2006

The success of childhood vaccination against hepatitis B relies on persistence of immunity into adolescence and adulthood. In 2000, two hexavalent vaccines with a hepatitis B component (Hexavac®, Infanrix hexa®) were introduced in Germany. Hexavac was withdrawn in 2005 amidst concerns about its long-term hepatitis B protection. We compared hepatitis B surface antibody (anti-HBs) levels in children fully vaccinated with Hexavac or Infanrix hexa (n=477) in a secondary data analysis of a large cross-sectional health survey in Germany. On average 2·4 years after vaccination, 25·3% of Hexavac vaccinees had anti-HBs levels <10 mIU/ml (95% CI 19·0–32·8) compared to 4·7% of Infanrix hexa vaccinees (95% CI 2·4–8·9). These findings suggest that short-term hepatitis B immunogenicity in Hexavac vaccinees may also be weaker. Further studies are warranted to assess whether Hexavac vaccinees should be re-vaccinated or receive a booster vaccination before these birth cohorts reach adolescence.

HEPATITIS B AND PREGNANCY, THE SCIENTIFIC BASIS FOR PERINATAL PREVENTION

Hepatitis B and its complications are one of the major global health problems. Around 2 billion individuals are infected by hepatitis B virus (HBV) worldwide, more than 350 million are chronically infected, and approximately 15 to 40 percents of them will develop serious complications such as liver cirrhosis, hepatic failure, or hepatocellular carcinoma (HCC). The worldwide prevalence of chronic HBV infection ranges from 0.1 to 20 percent and varies widely in different geographic areas. According to the prevalence rate, WHO has classified countries into 3 levels: high areas (>8%) such as Africa, Asia, Western Pacific and Middle East; intermediate areas (2–8%) such as South America and Eastern Europe, and low areas (<2%) such as Western Europe, North America, and Australia.

Immunisation practices in infants born prematurely: neonatologists' survey and clinical audit

AIM

To determine Australian neonatologists' recommendations for the immunisation of ex-preterm infants and compare their actual immunisation status with recommended Australian guidelines.

METHODS

A self-administered nine-part questionnaire of current immunisation practices was sent to all Neonatologists in Australia (2006). A complementary retrospective immunisation audit was conducted in two tertiary neonatal units in Melbourne. Hospital records and the Australian Childhood Immunisation Register (ACIR) were reviewed; consenting parents were interviewed and primary care physicians' vaccination records were requested. A random sample of preterm infants born between July 2003 and June 2005 at <32 weeks' gestation were selected.

RESULTS

(i) Neonatologists Survey: The response rate was 68% and the majority of neonatologists (89%) were aware of the current guidelines, but adherence to them varied from 43% to 79%. One-fifth of neonatologists personally do not receive annual influenza vaccination; and (ii) Immunisation Audit: Conducted between October 2006-May 2007 it included: 100 hospital records; 97 ACIR records; 47 parent interviews and 43 primary care vaccination records. Overall vaccination coverage was 90% at 12 months of age. Only 20% (10/50) of infants with chronic lung disease received an influenza vaccination. Vaccines were delayed by greater than one month in 15% of participants for the 2 month DTPa vaccine and 43% at 6 months.

CONCLUSIONS

The neonatologists survey highlighted variable adherence with immunisation guidelines. The audit confirmed preterm infants are frequently experiencing delayed vaccination and recommended additional vaccinations are often not being received. Formulation of strategies to ensure complete and timely immunisation are required, including better utilisation of the ACIR.

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.

[Immunization of the preterm infant]

Premature infants have an increased risk of experiencing infectious diseases, some of which are vaccine preventable diseases. Maturation of immune responses begins with exposition to environmental antigens and in premature infants as fast as in term-infants. Premature infants must be vaccinated at 2 months of age, whatever the gestational age. Acellular Pertussis vaccine and pneumococcal conjugate vaccine must be given as early as possible, at two months of age. Immunization schedule in premature infants is the same as in full-term infants : three injections one month apart with a pentavalent vaccine : Diphteria, Tetanus, Poliomyelitis, Pertussis and Haemophilus type b. First injection of hepatitis B vaccine must not be taken in account when this vaccine is given at birth to infants under 2 kg birth weight. Premature infants 6 months of age or older and experiencing chronic lung disease have to be vaccinated against influenza. In all cases, surroundings have to be vaccinated. Apnea and/or bradycardia have been reported within the 48 hours following vaccination in premature infants before 32 weeks of gestational age and justify giving their first injection of vaccine under cardiorespiratory monitoring. These injections will be given before discharge as often as possible.

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

Preterm infants are at increased risk of disease and hospitalization from a number of vaccine-preventable diseases. However, these same infants have immunologic immaturities that may impact vaccine responses. Larger premature infants mount immune responses to vaccines similar to those of full-term infants, but very premature infants (<28-32 weeks' gestation at birth) may have specific defects in vaccine responsiveness. Although there are minor differences in immunogenicity, the immune responses to diphtheria, tetanus, pertussis, and polio antigens are similar enough between full-term and premature infants that clinical consequences are unlikely to result. However, the immunogenicity of Haemophilus influenzae type b conjugate vaccines varies widely among studies of premature infants, and may be affected by the choice of conjugate protein, inclusion in a combination vaccine, and by an infant's overall health. Pneumococcal conjugate vaccine is efficacious in larger premature infants, but little information is available about immunogenicity in smaller premature infants. Meningococcal group C conjugate vaccine appears immunogenic in even very premature infants, but the duration of immunity may be limited. Hepatitis B vaccine given at birth appears poorly immunogenic in infants with birth weights <1500-2000 g, with delay in the administration of the first dose yielding improved immunogenicity. Few data on influenza vaccine in premature infants are available, but infants with pulmonary disease may respond less robustly than others. Bacille Calmette Guérin vaccine appears to be most immunogenic if delayed until at least 34-35 weeks' postmenstrual age in very premature infants, although there may be non-specific advantages to its earlier administration. Premature infants may have persistently lower antibody titers than full-term infants, even years after initial immunization. Sick premature infants experience increased episodes of apnea or cardiorespiratory compromise following vaccine administration, necessitating careful monitoring. Specific factors that impair immune response, quality of the immune response, and safety and immunogenicity evaluation of new vaccines in premature infants are topics needing further research. Premature infants are at significant risk for decisions from healthcare providers that delay beginning and completing their vaccine regimens. A major challenge facing those who care for these infants is the provision of timely immunization.

Measles-mumps-rubella and varicella vaccine responses in extremely preterm infants

OBJECTIVE

Extremely preterm infants mount lower antibody responses than term infants to several vaccines. The objective of this study was to measure the immunogenicity of measles-mumps-rubella and varicella vaccines in preterm and term children.

METHODS

Immune status before immunization and immune response after immunization with measles-mumps-rubella and varicella vaccines at 15 months of age were compared in 32 infants, 16 of whom were preterm (< 29 weeks' gestation) and 16 of whom were term (> or = 37 weeks' gestation) at birth. Blood was drawn before vaccination and 3 to 6 weeks thereafter. Measles antibody was measured by plaque reduction neutralization assay. Mumps and rubella immunoglobulin G were measured in available sera by enzyme-linked fluorescent immunoassay. Varicella immunoglobulin G was measured in available sera by glycoprotein enzyme-linked immunosorbent assay. Values that were above or below the assay limits were assigned values double or half those limits, respectively. The primary outcome was the geometric mean antibody titer.

RESULTS

Preterm children had lower mumps and rubella geometric mean titers than did term children before vaccine, and nearly all children were seronegative for each of the 4 vaccine antigens before immunization. Measles, mumps, rubella, and varicella geometric mean titers were similar between groups after vaccine. All children were seropositive for measles after vaccine, whereas 13 of 14 preterm and 11 of 13 term children were seropositive for mumps, 13 of 14 preterm and 13 of 13 term children were seropositive for rubella, and 11 of 16 preterm and 9 of 15 term children were seropositive for varicella.

CONCLUSIONS

Preterm children mounted antibody responses that were similar to those of term children after measles-mumps-rubella and varicella vaccines at 15 months of age.

Antipolyribosyl ribitol phosphate response of premature infants to primary and booster vaccination with a combined diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated polio virus/Haemophilus influenzae type b vaccine

BACKGROUND

Prematurity may be a risk factor for Haemophilus influenzae type b vaccine failure. This article evaluates the Haemophilus influenzae type b immunogenicity of a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenzae type b vaccine in preterm infants (< 37 weeks' gestation).

METHODS

This was an open-label, parallel group study. Preterm (N = 94) and term infants (N = 92) received 3 doses of a diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenzae type b vaccine at 2, 4, and 6 months with a booster dose at 18 to 20 months. Antipolyribosyl ribitol phosphate antibody concentrations were determined in serum samples taken before and 1 month after primary and booster vaccination.

RESULTS

Postprimary seroprotection rates (antipolyribosyl ribitol phosphate > or = 0.15 microg/mL) were lower in preterm than in term infants (92.5% vs 97.8%), with antipolyribosyl ribitol phosphate geometric mean concentrations of 2.241 vs 4.247 microg/mL. A progressive reduction in immune response to the Haemophilus influenzae type b antigen was observed with decreasing length of gestation and decreasing birth weight when cutoff > or = 1 microg/mL was considered. Prebooster seroprotection rates and antipolyribosyl ribitol phosphate geometric mean concentrations were low in both groups (antipolyribosyl ribitol phosphate > or = 1.0 microg/mL in 10.7% of preterm and 28.4% of term infants). A vigorous response to booster vaccination was seen in both groups, with no differences in postbooster seroprotection rates or antipolyribosyl ribitol phosphate geometric mean concentrations between the 2 groups (antipolyribosyl ribitol phosphate > or = 1.0 microg/mL in 100% of preterm and 98.5% of term infants).

CONCLUSIONS

Primary vaccination with a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenzae type b vaccine at 2, 4, and 6 months with a booster dose at 18 to 20 months elicits a satisfactory antipolyribosyl ribitol phosphate response in preterm infants compared with term controls. Immunologic response decreased with decreased gestational age and birth weight.

Immunisation of premature infants

Premature infants are at increased risk of vaccine preventable infections, but audits have shown that their vaccinations are often delayed. Early protection is desirable. While the evidence base for immunisation of preterm infants is limited, the available data support early immunisation without correction for gestational age. For a number of antigens the antibody response to initial doses may be lower than that of term infants, but protective concentrations are often achieved and memory successfully induced. A 2-3-4 month schedule may be preferable for immunisation of preterm infants in order to achieve protection as early as possible, but an additional dose may be required to achieve persistence of protection. This update focuses on the use of routine childhood vaccines in premature infants.

Protection against hepatitis B by the Butang® recombinant vaccine in newborn children in South Brazil

The prevention of hepatitis B by vaccination is one of the most efficient tools to avoid the transmission of the virus. This study evaluated the immunogenicity of the national vaccine Butang in children born in Campo Mourão City, state of Paraná, Brazil, aged 7 to 12 months, by determining the anti-HBsAg antibodies levels after completion of the National Immunization Program Protocol for hepatitis B. All 70 children evaluated by the MEIA method (immune-enzymatic micro particles) showed seroconversion to the Butang vaccine. Nine children (12.9%) presented a low response, with anti-HBs titers between 11 and 100 mUI/ml; 39 children (55.7%) showed a good response to the vaccine, with titers between 101 and 1000 mUI/ml; and 22 children (31.4%) showed antibodies titers higher than 1000 mUI/ml. The mean titer of the anti-HBs antibody titers was 1408.1 +/- 2870.26 mUI/ml (15.7 to 19560.0 m UI/ml). The levels of antibodies produced by the prematurely-born children were not statistically different from those found in the newborns. Fifty-five children were also evaluated through the ELFA method (ELISA with a final detection in fluorescence), which presented similar results. The results obtained in our study corroborated the effectiveness of the national vaccine Butang in newborn children of Campo Mourão City, Paraná, even if they were premature.

Hepatitis B vaccination is effective for babies weighing less than 1800 g

AIM

This trial studied the effectiveness of early hepatitis B (HepB) immunisation in babies weighing less than 1800 grams, born of HepB surface-antigen-negative mothers.

METHODS

The first vaccine dose was given once clinical stability was achieved, with second and third doses given 1 and 6 months later, respectively. HepB serology, done using Abbott ElA (phase 1) and Abbott Axsym (phase 2) before and after June 2001, respectively, was checked at birth (Sero1), prior to (Sero2) and 6 months after (Sero3) the third dose. A booster dose was recommended when Sero3 showed a non-immune status (< 10 mIU/mL).

RESULTS

Median birth weight and gestational age (n = 118) were 1295 [range 475, 1780] g and 31 [range 24, 37] completed weeks, respectively. Sero1 (median age of 4 [range 1, 34] days) showed 64% (n = 113) to be non-immune. The first dose of vaccine was administered at a median weight of 1268 [range 530, 1790] g, median age of 6 [range 1-63] days and median post-menstrual age of 32 [range 24-37] completed weeks. Sero2 (median age of 179 [range 112-260] days), for 110 babies (93.2%) showed immunity in 48.2% (median titres--Phase 1: 26 [range 10, 150] mIU/mL; Phase 2: 34 [range 10, 1000] mIU/mL). Sero3 revealed seroprotection in 77.8% (median titres--Phase 1: 102 [range 12, 150] mIU/mL; Phase 2: 162 [range 16, 1000] mIU/mL). The more mature the bady at time of first dose, the more likely he is to achieve seroprotection (85% amongst those administered at and beyond 33 weeks; 91% among those administered at and beyond Day 10 at Sero3).

CONCLUSIONS

Early HepB immunisation in infants < 1800 g can be safely recommended, with booster doses necessary at 1 year for some infants.