Controlled trial of immune response of preterm infants to recombinant hepatitis B and inactivated poliovirus vaccines administered simultaneously shortly after birth

Quantitative Analysis of the Instant and Persistent Inhibition Effects of Maternal Poliovirus Antibodies on the Immune Response in a Phase IV Trial of a Sabin Strain-Based Inactivated Poliovirus Vaccine

BACKGROUND

An inactivated poliomyelitis vaccine made from Sabin strains (sIPVs) has widely been used in China since 2015. However, the quantitative data on the instant and persistent inhibition effects of maternal poliovirus antibodies on the immune response to sIPV priming and booster vaccination have not been available yet.

OBJECTIVE

In this study, we aim to explore and quantify the instant and persistent inhibition effect of maternal poliovirus antibodies on the immune response elicited by sIPV primary and booster vaccination.

METHODS

The immunogenicity data consisting of the days 0 and 30 after the prime and booster vaccination of the sIPV in a phase IV trial were pooled for a quantitative analysis of the inhibition effect of maternal poliovirus antibody. The geometric mean ratio (GMR) was calculated using linear regression models, representing that every 2-fold higher maternal poliovirus antibody titer may result in a (1-GMR) lower postimmunization antibody titer.

RESULTS

The GMRs for poliovirus types 1, 2, and 3 were 0.79 (0.77-0.82), 0.85 (0.81-0.89), and 0.87 (0.83-0.91) at 30 days after the priming series, 0.86 (0.83-0.89), 0.81 (0.76-0.85), and 0.86 (0.80-0.93) at one year after the priming series, and 0.96 (0.94-0.99), 0.89 (0.86-0.93), and 0.98 (0.93-1.03) at 30 days after the booster dose. The inhibition effect continued to exist until the booster dose 1 year later, and such a persistent inhibition effect was almost attenuated for poliovirus types 1 and 3, and partly reduced for type 2 at 30 days after the booster dose.

CONCLUSION

A wider interval between the four sIPV doses might be a consideration for reducing the effect of maternal antibodies and subsequently eliciting and maintaining higher antibody levels to protect against poliovirus transmission and infection at the final stage of polio eradication in the global world. This study's clinical trial registry number is NCT04224519.

Neutralizing anti-polio antibody titre in newborn babies in post-polio eradication period in Nigeria

BACKGROUND

According to Polio Eradication and Endgame Strategic Plan 2019-2023 (PEESP), countries that achieved wild polio elimination is expected to replace oral polio vaccine (OPV) which has a risk of vaccine-derived poliovirus, Inactivated Polio Vaccine (IPV). It is important to determine the earliest time in the age of a child at which IPV could be introduced into the country's routine immunization schedule for effectiveness especially as it concerns neutralizing effect of trans-placental transmitted antibodies which usually does not affect OPV. In this study, the level of poliovirus neutralizing antibody titre among neonates at birth was evaluated.

METHODS

A cross-sectional study of mother-baby pair. The serum level of the neutralizing Poliovirus antibody IgG titre was done by the Enzyme Linked Immunosorbent Assay (ELISA) technique.

RESULTS

There was 100% transfer of maternal passive antibodies to their babies. The mean poliovirus antibody titre among neonates was 21.8 IU/L which was above the neutralizing titre level. Most (85.7%) babies antibody level correlate positively with that of their mothers.

CONCLUSION

The transferred maternal antibodies to the babies are still very high at birth, and capable of dampening the immunity of IPV if introduced early. Programme managers should evaluate the impact and benefit of given booster dose of IPV to pregnant mothers to increase the titre level in their babies. This will be very necessary when the OPV is withdrawn from the immunization schedule.

Outcomes of Hepatitis B Immunoglobulin and Hepatitis B Vaccination in High-Risk Newborns Born to HBeAg-positive Mothers

BACKGROUND

To evaluate the protective efficacy of a hepatitis B (HB) vaccination program in Taiwan among high-risk children.

MATERIAL AND METHODS

Children born to HBeAg-positive mothers from 2001 to 2010 were invited back. Blood samples for hepatitis B virus (HBV) seromarkers were taken and the children underwent hepatobiliary ultrasonography. Perinatal factors including delivery mode and vaccination history were collected from their medical records. According to the results of HBV serological markers, the children were initially classified into five groups: HBV naïve, HB vaccine responder, HBsAg carrier, recovered from HBV infection, and anti-HBc-positive alone. Children in the HBV naïve and anti-HBc-positive alone groups who presented with an anamnestic response after a booster HB vaccine were re-assigned to the vaccine responder and recovered from infection groups, respectively.

RESULTS

All of the 196 enrolled children received postnatal hepatitis B immunoglobulin (HBIG) and HB vaccinations, of whom one was HBV naïve (0.5%), 109 were vaccine responders (55.6%), 21 were carriers (10.7%), and 65 recovered from infection (33.2%). Among the 21 carriers, 14 (66.7%) presented in the immunotolerant phase. Cesarean section was the only significant perinatal factor between the carriers (5.3%) and those who recovered from infection (37.7%) (p=0.007).

CONCLUSIONS

In this study, there was a 43.9% HBV infection rate and 10.7% HBsAg carrier rate in high-risk Taiwanese children even after receiving HBIG and HB vaccinations. Cesarean section may protect newborns from becoming HBsAg carriers, while HBV genotype and time of HBIG injection did not contribute to the HBV carrier rate.

Immunogenicity and safety of the inactivated poliomyelitis vaccine made from Sabin strains in a phase IV clinical trial for the vaccination of a large population

As a recently launched novel vaccine used as one of the vaccines for the final eradication of polios worldwide, complete data on the consistency and immunogenicity characteristics of the inactivated poliomyelitis vaccine made from the Sabin strain (sIPV) and its safety in large-scale populations are required to support the future use of this vaccine worldwide. A phase IV clinical trial was conducted to perform an immunogenicity evaluation of lot-to-lot consistency of three commercial batches of sIPV in 1200 infants and to investigate the vaccine's safety on a large-scale in 20,019 infants for active monitoring and 29,683 infants for passive monitoring through the Adverse Event Following Immunization (AEFI) reporting system in China. In the immunogenicity evaluation, the average seroconversion rates for type I, type II and type III of the three groups were 99.83%, 98.93% and 99.44%, respectively. No differences in the seroconversion rate and the GMT ratios were noted in the pair-to-pair comparisons. In the large-scale safety evaluation, most adverse reactions occurred 0-30 days after the first doses, and the common local and systemic reactions were similar to those in the phase III clinical trial, with low incidence in both activated and passive monitoring. In conclusion, sIPV exhibits good lot-to-lot consistency and safety in large-scale populations; thus, it is qualified to serve as one of the vaccines for use in eradicating all wild and vaccine-derived polioviruses worldwide in the near future. Clinic Trial Registration. NCT04224519 and NCT04220515.

The effect of maternal poliovirus antibodies on the immune responses of infants to poliovirus vaccines

Background

Maternal poliovirus antibodies could provide passive immunity to the newborns from poliovirus infection during their first few months of life, but they may impair the immune responses of infants to the poliovirus vaccine as well. In our study, we pooled the data from three clinical trials of the inactivated poliovirus vaccine (IPV) based on Sabin strains to investigate the effect of maternal poliovirus antibodies on the immune responses of infants to poliovirus vaccines.

Methods

There were five groups in the pooled analysis, including low-dose Sabin IPV, medium-dose Sabin IPV, high-dose Sabin IPV, control Sabin IPV, and control Salk IPV groups. We reclassified the infants in different groups according to their maternal poliovirus antibodies by two methods, the first one included maternal antibody negative (< 1:8) and maternal antibody positive (≥1:8), and the second one included maternal antibody titer < 1:8, 1:8 ~ < 1:32 and ≥ 1:32. Then, we compared the geometric mean titers (GMTs), geometric mean antibody fold increases (GMIs) and seroconversion rates of poliovirus type-specific neutralizing antibodies after vaccination among participants with different maternal poliovirus antibody levels.

Results

The GMTs and GMIs of three types of poliovirus antibodies after vaccination in maternal antibody negative participants were significantly higher than those in maternal antibody positive participants. The seroconversion rates of type II and type III poliovirus antibodies in maternal antibody positive participants were significantly lower than those in maternal antibody negative participants. Among participants with maternal antibody titer < 1:8, 1:8 ~ < 1:32 and ≥ 1:32, the GMTs and GMIs of three types of poliovirus antibodies after vaccination showed a tendency to decline with the increasing of maternal antibody levels. The seroconversion rates of three types of poliovirus antibodies in participants with maternal antibody titer ≥1:32 were significantly lower than those in participants with maternal antibody titer < 1:8 and 1:8 ~ < 1:32.

Conclusions

Maternal poliovirus antibodies interfered with the immune responses of infants to poliovirus vaccines, and a high level of maternal antibodies exhibited a greater dampening effect.

Trial registration

ClinicalTrials.govNCT04264598 February 11, 2020; ClinicalTrials.govNCT04264546 February 11, 2020; ClinicalTrials.govNCT03902054 April 3, 2019. Retrospectively registered.

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

CONTEXT

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

EVIDENCE ACQUISITION

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

EVIDENCE SYNTHESIS

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

CONCLUSIONS

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

Safety and immunogenicity of experimental stand-alone trivalent, inactivated Sabin-strain polio vaccine formulations in healthy infants: A randomized, observer-blind, controlled phase 1/2 trial

BACKGROUND

To increase the global supply of affordable IPV vaccine, preferably using Sabin viruses to comply with GAPIII requirements, Takeda has assessed three dosages of a stand-alone sIPV.

METHODS

In this phase I/II study two cohorts of 40 adults and 60 toddlers, respectively, were initially assessed for safety after receiving high-dosage sIPV compared with placebo (adults) or Salk IPV (toddlers). A cohort of 240 infants was then enrolled and randomized (1:1:1:1) to receive low-, medium- or high-dosage sIPV, or a reference Salk IPV in a three-dose primary schedule at 6, 10 and 14 weeks of age. Parents completed safety diaries for 4 weeks after each dose, and immunogenicity was measured as neutralization antibody titers at baseline and four weeks after vaccination.

RESULTS

All vaccinations were generally well-tolerated and sIPV had a comparable safety profile to the control arm in adults or the reference Salk IPV vaccine in toddlers and infants. Infants displayed dosage-dependent immune responses to sIPV when assayed using Sabin strains, which were equivalent to the reference IPV in the high-dosage sIPV group for serotypes 1 and 2, but not for Sabin and Salk serotype 3. Seroconversion rates (SCR) of the low- and medium-dosage groups were significantly lower than the Salk IPV group for both Sabin and Salk serotypes 1 and type 2 (p < 0.05), with no significant differences for Salk or Sabin serotypes 3. Responses to sIPV, particularly to Sabin types 1 and 2, were higher in initially seronegative infants, indicating possible interference by maternally-derived antibodies.

CONCLUSIONS

A novel stand-alone Sabin-based IPV vaccine was well tolerated with an acceptable safety profile, but less immunogenic than reference Salk IPV at 6, 10 and 14 weeks of age for Salk serotypes 1 and 2, with apparent interference by maternal antibodies. Additional preclinical assessments will be made before any further clinical development.

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.

Sequential inactivated (IPV) and live oral (OPV) poliovirus vaccines for preventing poliomyelitis

BACKGROUND

Poliomyelitis mainly affects unvaccinated children under five years of age, causing irreversible paralysis or even death. The oral polio vaccine (OPV) contains live attenuated virus, which can, in rare cases, cause a paralysis known as vaccine-associated paralytic polio (VAPP), and also vaccine-derived polioviruses (VDPVs) due to acquired neurovirulence after prolonged duration of replication. The incidence of poliomyelitis caused by wild polio virus (WPV) has declined dramatically since the introduction of OPV and later the inactivated polio vaccine (IPV), however, the cases of paralysis linked to the OPV are currently more frequent than those related to the WPV. Therefore, in 2016, the World Health Organization (WHO) recommended at least one IPV dose preceding routine immunisation with OPV to reduce VAPPs and VDPVs until polio could be eradicated.

OBJECTIVES

To assess the effectiveness, safety, and immunogenicity of sequential IPV-OPV immunisation schemes compared to either OPV or IPV alone.

SEARCH METHODS

In May 2019 we searched CENTRAL, MEDLINE, Embase, 14 other databases, three trials registers and reports of adverse effects on four web sites. We also searched the references of identified studies, relevant reviews and contacted authors to identify additional references.

SELECTION CRITERIA

Randomised controlled trials (RCTs), quasi-RCTs, controlled before-after studies, nationwide uncontrolled before-after studies (UBAs), interrupted time series (ITS) and controlled ITS comparing sequential IPV-OPV schedules (one or more IPV doses followed by one or more OPV doses) with IPV alone, OPV alone or non-sequential IPV-OPV combinations.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 21 studies: 16 RCTs involving 6407 healthy infants (age range 96 to 975 days, mean 382 days), one ITS with 28,330 infants and four nationwide studies (two ITS, two UBA). Ten RCTs were conducted in high-income countries; five in the USA, two in the UK, and one each in Chile, Israel, and Oman. The remaining six RCTs were conducted in middle-income countries; China, Bangladesh, Guatemala, India, and Thailand. We rated all included RCTs at low or unclear risk of bias for randomisation domains, most at high or unclear risk of attrition bias, and half at high or unclear risk for conflict of interests. Almost all RCTs were at low risk for the remaining domains. ITSs and UBAs were mainly considered at low risk of bias for most domains. IPV-OPV versus OPV It is uncertain if an IPV followed by OPV schedule is better than OPV alone at reducing the number of WPV cases (very low-certainty evidence); however, it may reduce VAPP cases by 54% to 100% (three nationwide studies; low-certainty evidence). There is little or no difference in vaccination coverage between IPV-OPV and OPV-only schedules (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.96 to 1.06; 1 ITS study; low-certainty evidence). Similarly, there is little or no difference between the two schedule types for the number of serious adverse events (SAEs) (RR 0.88, 95% CI 0.46 to 1.70; 4 studies, 1948 participants; low-certainty evidence); or the number of people with protective humoral response P1 (moderate-certainty evidence), P2 (for the most studied schedule; two IPV doses followed by OPV; low-certainty evidence), and P3 (low-certainty evidence). Two IPV doses followed by bivalent OPV (IIbO) may reduce P2 neutralising antibodies compared to trivalent OPV (moderate-certainty evidence), but may make little or no difference to P1 or P2 neutralising antibodies following an IIO schedule or OPV alone (low-certainty evidence). Both IIO and IIbO schedules may increase P3 neutralising antibodies compared to OPV (moderate-certainty evidence). It may also lead to lower mucosal immunity given increased faecal excretion of P1 (low-certainty evidence), P2 and P3 (moderate-certainty evidence) after OPV challenge. IPV-OPV versus IPV It is uncertain if IPV-OPV is more effective than IPV alone at reducing the number of WPV cases (very low-certainty evidence). There were no data regarding VAPP cases. There is no clear evidence of a difference between IPV-OPV and OPV schedules for the number of people with protective humoral response (low- and moderate-certainty evidence). IPV-OPV schedules may increase mean titres of P1 neutralising antibodies compared to OPV alone (low- and moderate-certainty evidence), but the effect on P2 and P3 titres is not clear (very low- and moderate-certainty evidence). IPV-OPV probably reduces the number of people with P3 poliovirus faecal excretion after OPV challenge with IIO and IIOO sequences (moderate-certainty evidence), and may reduce the number with P2 (low-certainty evidence), but not with P1 (very low-certainty evidence). There may be little or no difference between the schedules in number of SAEs (RR 0.92, 95% CI 0.60 to 1.43; 2 studies, 1063 participants, low-certainty evidence). The number of persons with P2 protective humoral immunity and P2 neutralising antibodies are probably lower with most sequential schemes without P2 components (i.e. bOPV) than with trivalent OPV or IVP alone (moderate-certainty evidence). IPV (3)-OPV versus IPV (2)-OPV One study (137 participants) showed no clear evidence of a difference between three IPV doses followed by OPV and two IPV doses followed by OPV, on the number of people with P1 (RR 0.98, 95% CI 0.93 to 1.03), P2 (RR 1.00, 95% CI 0.97 to 1.03), or P3 (RR 1.01, 95% CI 0.97 to 1.05) protective humoral and intestinal immunity; all moderate-certainty evidence. This study did not report on any other outcomes.

AUTHORS' CONCLUSIONS

IPV-OPV compared to OPV may reduce VAPPs without affecting vaccination coverage, safety or humoral response, except P2 with sequential schemes without P2 components, but increase poliovirus faecal excretion after OPV challenge for some polio serotypes. Compared to IPV-only schedules, IPV-OPV may have little or no difference on SAEs, probably has little or no effect on persons with protective humoral response, may increase neutralising antibodies, and probably reduces faecal excretion after OPV challenge of certain polio serotypes. Using three IPV doses as part of a IPV-OPV schedule does not appear to be better than two IPV doses for protective humoral response. Sequential schedules during the transition from OPV to IPV-only immunisation schedules seems a reasonable option aligned with current WHO recommendations. Findings could help decision-makers to optimise polio vaccination policies, reducing inequities between countries.

Effect of maternal antibody on the infant immune response to inactivated poliovirus vaccines made from Sabin strains

This study aimed to evaluate the effect of maternally derived antibody on the immunogenicity of Sabin IPV. A total of 600 infants were randomized to receive one of the five different vaccines: the high- (group A), medium- (group B) or low-dose (group C) of investigational Sabin IPV, the control Salk IPV (group D) or the control Sabin IPV (group E), at 2, 3 and 4 months of age. The post-vaccination GMTs, GMIs and seroconversion rates of poliovirus type-specific neutralizing antibody were analyzed for different maternal antibody levels. The correlations between maternal antibody levels and post-vaccination antibody responses were also modeled by linear regressions. The post-vaccination GMTs were significantly lower among infants with high maternal antibody titers for poliovirus type 1 or 2 mainly in the groups B, C, D and E. The GMIs and seroconversion rates decreased significantly with the increase of maternal antibody levels in all the five groups. In the groups A, B and C, maternal antibody levels were negatively associated with the post-vaccination antibody titers (for poliovirus type 1 and 2) and the fold increases of post-vaccination antibody (for all the 3 poliovirus types). With the reduce of potency of the investigational Sabin IPVs, the linear regression coefficients increased accordingly in the groups A, B and C. In conclusion, high levels of maternal poliovirus antibody could attenuate the immune responses to the Sabin IPVs. Altering the potency of the investigational Sabin IPVs could alter the associations between maternal antibody levels and the serologic responses of infants.

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.

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.

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.

Oral and inactivated poliovirus vaccines in the newborn: a review

BACKGROUND

Oral poliovirus vaccine (OPV) remains the vaccine-of-choice for routine immunization and supplemental immunization activities (SIAs) to eradicate poliomyelitis globally. Recent data from India suggested lower than expected immunogenicity of an OPV birth dose, prompting a review of the immunogenicity of OPV or inactivated poliovirus vaccine (IPV) when administered at birth.

METHODS

We evaluated the seroconversion and reported adverse events among infants given a single birth dose (given ≤7 days of life) of OPV or IPV through a systematic review of published articles and conference abstracts from 1959 to 2011 in any language found on PubMed, Google Scholar, or reference lists of selected articles.

RESULTS

25 articles from 13 countries published between 1959 and 2011 documented seroconversion rates in newborns following an OPV dose given within the first seven days of life. There were 10 studies that measured seroconversion rates between 4 and 8 weeks of a single birth dose of TOPV, using an umbilical cord blood draw at the time of birth to establish baseline antibody levels. The percentage of newborns who seroconverted at 8 weeks range from 6-42% for poliovirus type 1, 2-63% for type 2, and 1-35% for type 3. For mOPV type 1, seroconversion ranged from 10 to 76%; mOPV type 3, the range was 12-58%; and for the one study reporting bOPV, it was 20% for type 1 and 7% for type 3. There were four studies of IPV in newborns with a seroconversion rate of 8-100% for serotype 1, 15-100% for serotype 2, and 15-94% for serotype 3, measured at 4-6 weeks of life. No serious adverse events related to newborn OPV or IPV dosing were reported, including no cases of acute flaccid paralysis.

CONCLUSIONS

There is great variability of the immunogenicity of a birth dose of OPV for reasons largely unknown. Our review confirms the utility of a birth dose of OPV, particularly in countries where early induction of polio immunity is imperative. IPV has higher seroconversion rates in newborns and may be a superior choice in countries which can afford IPV, but there have been few studies of an IPV dose for newborns.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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.

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.

Hepatitis B immunisation for newborn infants of hepatitis B surface antigen-positive mothers

BACKGROUND

Hepatitis B vaccine and hepatitis B immunoglobulin are considered for newborn infants of HBsAg-positive mothers to prevent hepatitis B infection.

OBJECTIVES

To assess the beneficial and harmful effects of hepatitis B vaccines and hepatitis B immunoglobulin in newborn infants of HBsAg-positive mothers.

SEARCH STRATEGY

Trials were identified through The Cochrane Neonatal Group Controlled Trials Register, The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials in The Cochrane Library, MEDLINE, and EMBASE (until February 2004), authors of trials, and pharmaceutical companies.

SELECTION CRITERIA

Randomised clinical trials comparing: plasma-derived vaccine (PDV) or recombinant vaccine (RV) versus no intervention, placebo, or other active vaccines; hepatitis B immunoglobulin versus no intervention, placebo, or other control immunoglobulin; as well as PDV or RV plus hepatitis B immunoglobulin versus no intervention, placebo, or other control vaccines or immunoglobulin.

DATA COLLECTION AND ANALYSIS

Outcomes are assessed at maximal follow-up. The primary outcome measure was hepatitis B occurrence, based on a blood specimen positive for HBsAg, HBeAg, or antibody to hepatitis B core antigen (anti-HBc). Binary outcomes are reported as relative risks (RR) with 95% confidence interval (CI). Subgroup analyses were performed with regard to methodological quality of the trial, mother's HBe-Ag status, and time of immunisation after birth.

MAIN RESULTS

We identified 29 randomised clinical trials, five of which were considered high quality. Only three trials reported inclusion of hepatitis B e-antigen negative mothers. Compared with placebo/no intervention, vaccine reduced hepatitis B occurrence (RR 0.28, 95% confidence interval (CI) 0.20 to 0.40, 4 trials). No significant differences of hepatitis B occurrence were found comparing recombinant vaccine (RV) versus plasma-derived vaccine (PDV) (RR 1.00, 95% CI 0.71 to 1.42, 4 trials) and high-dose versus low-dose vaccine (PDV: RR 0.97, 95% CI 0.55 to 1.68, 3 trials; RV: RR 0.78, 95% CI 0.31 to 1.94, 1 trial). Compared with placebo/no intervention, hepatitis B immunoglobulin or the combination of vaccine plus hepatitis B immunoglobulin reduced hepatitis B occurrence (hepatitis B immunoglobulin: RR 0.50, 95% CI 0.41 to 0.60, 1 trial; PDV plus hepatitis B immunoglobulin: RR 0.08, 95% CI 0.03 to 0.17, 3 trials). Compared with vaccine, vaccine plus hepatitis B immunoglobulin reduced hepatitis B occurrence (RR 0.54, 95% CI 0.41 to 0.73, 10 trials). Hepatitis B vaccine and hepatitis B immunoglobulin seem safe, but few trials reported on adverse events.

AUTHORS' CONCLUSIONS

Vaccine, hepatitis B immunoglobulin, and vaccine plus hepatitis B immunoglobulin prevent hepatitis B occurrence in newborn infants of HBsAg positive mothers.

DT5aP-Hib-IPV and MCC vaccines: preterm infants' response to accelerated immunisation

AIMS

To describe the immune response of preterm infants to combined diphtheria/tetanus/5 component acellular pertussis-Haemophilus influenzae type b inactivated polio vaccine (DT5aP-Hib-IPV) and meningococcal serogroup C conjugate vaccine (MCC) under accelerated schedule. To compare results with term infants immunised with DT5aP-Hib-IPV and with historical data from preterm infants immunised with a DT3 component aP-Hib vaccine.

METHODS

Prospective observational study in preterm infants born at <32 weeks gestation with comparison to contemporary cohort of term infants. DT5aP-Hib-IPV and MCC vaccines were given at 2, 3, and 4 months.

RESULTS

Fifty preterm infants (mean gestational age 28.5 weeks) completed the study. After three doses of vaccines Hib polysaccharide IgG geometric mean concentration (GMC) was 1.21 microg/ml with 80% > or =0.15 microg/ml; MCC serum bactericidal assay geometric mean titre (GMT) was 1245 with 100% > or =8. All infants achieved protective titres to diphtheria, tetanus, and the three poliovirus types with > or =80% achieving protective rises in IgG against the five pertussis antigens.

CONCLUSION

Preterm infants immunised with DT5aP-Hib-IPV and MCC vaccines show IgG responses to Hib and MCC greater than seen historically in both term and preterm infants with a DT3aP-Hib vaccine, and for pertussis antigens and poliovirus type 1 responses similar to that seen in term infants immunised with DT5aP-Hib-IPV. Responses to poliovirus types 2 and 3 are reduced, but all infants achieved protective titres.