Immunogenicity of hepatitis B vaccine in healthy very low birth weight infants

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.

Prevention of Hepatitis B Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices

HEPATITIS B VIRUS (HBV) IS TRANSMITTED VIA BLOOD OR SEXUAL CONTACT. PERSONS WITH CHRONIC HBV INFECTION ARE AT INCREASED RISK FOR CIRRHOSIS AND LIVER CANCER AND REQUIRE MEDICAL CARE. THIS REPORT UPDATES AND SUMMARIZES PREVIOUSLY PUBLISHED RECOMMENDATIONS FROM THE ADVISORY COMMITTEE ON IMMUNIZATION PRACTICES (ACIP) AND CDC REGARDING THE PREVENTION OF HBV INFECTION IN THE UNITED STATES. ACIP RECOMMENDS TESTING ALL PREGNANT WOMEN FOR HEPATITIS B SURFACE ANTIGEN (HBSAG), AND TESTING HBSAG-POSITIVE PREGNANT WOMEN FOR HEPATITIS B VIRUS DEOXYRIBONUCLEIC ACID (HBV DNA); ADMINISTRATION OF HEPB VACCINE AND HEPATITIS B IMMUNE GLOBULIN (HBIG) FOR INFANTS BORN TO HBV-INFECTED WOMEN WITHIN 12 HOURS OF BIRTH, FOLLOWED BY COMPLETION OF THE VACCINE SERIES AND POSTVACCINATION SEROLOGIC TESTING; UNIVERSAL HEPATITIS B VACCINATION WITHIN 24 HOURS OF BIRTH, FOLLOWED BY COMPLETION OF THE VACCINE SERIES; AND VACCINATION OF CHILDREN AND ADOLESCENTS AGED <19 YEARS WHO HAVE NOT BEEN VACCINATED PREVIOUSLY. ACIP RECOMMENDS VACCINATION OF ADULTS AT RISK FOR HBV INFECTION, INCLUDING UNIVERSAL VACCINATION OF ADULTS IN SETTINGS IN WHICH A HIGH PROPORTION HAVE RISK FACTORS FOR HBV INFECTION AND VACCINATION OF ADULTS REQUESTING PROTECTION FROM HBV WITHOUT ACKNOWLEDGMENT OF A SPECIFIC RISK FACTOR. THESE RECOMMENDATIONS ALSO PROVIDE CDC GUIDANCE FOR POSTEXPOSURE PROPHYLAXIS FOLLOWING OCCUPATIONAL AND OTHER EXPOSURES. THIS REPORT ALSO BRIEFLY SUMMARIZES PREVIOUSLY PUBLISHED AMERICAN ASSOCIATION FOR THE STUDY OF LIVER DISEASEST GUIDELINES FOR MATERNAL ANTIVIRAL THERAPY TO REDUCE PERINATAL HBV TRANSMISSION.

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.

Serologic Responses After Hepatitis B Vaccination in Preterm Infants Born to Hepatitis B Surface Antigen-Positive Mothers: Singapore Experience

BACKGROUND

The Advisory Committee on Immunization Practices (ACIP) recommends a 4-dose vaccination schedule for preterm low birth weight infants (<2 kg) and a 3-dose vaccination schedule for preterm infants (≥2 kg) born to hepatitis B surface antigen (HBsAg)-positive mothers. However, data remain limited for these high-risk infants, and the optimal dosing schedule in Asia is not well established.

AIM

The aim of this study was to evaluate the serologic vaccine responses in preterm infants born to HBsAg-positive mothers using current vaccination guidelines.

METHODS

Preterm babies of gestation less than 37 completed weeks born to HBsAg-positive mothers were prospectively recruited during 6 years (June 2009 to December 2015) and retrospectively recruited via convenience sampling in 2 years (June 2013 to April 2015) in 2 tertiary pediatric centers. The preterm infants were given 4 or 3 vaccine doses as per ACIP 2005 guidelines. Vaccine response was defined as achieving hepatitis B surface antibody values of >10 IU/L [Abbott Architect (Abbott Laboratories, Chicago, IL)] at 9 months of chronologic age.

RESULTS

A total of 24 preterm infants were recruited. Four had a birth weight <2 kg. Of 23 surviving infants, all were negative for HBsAg. One baby (4.5%) did not achieve adequate vaccine response. All 4 infants with birth weight <2 kg achieved seroprotective values.

CONCLUSION

The current ACIP-recommended vaccination schedule results in adequate antibody responses in preterm infants of HBsAg-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.

[Vaccination against hepatitis B. Impact of vaccination programmes after 20 years of use in Spain. Is it time for a change?]

The highest incidence rate of hepatitis B (HB) in Spain is detected in adults between 20 and 54 years old, whereas the incidence in children under 1 year old is almost nil. The low prevalence of HB in children under 1 year is mainly due to the success of gestational screening strategies for the detection of HBsAg(+) in pregnant women, and vaccination campaigns during childhood. Currently, in Spain, the last dose of the HB included in the national childhood immunization program is administered at 6 months of age, although some studies show that delaying the age of the administration of the last dose of HB vaccine and increasing the time between doses, may improve immune memory by offering greater protection against this virus in the adulthood. In this article, the impact of HB vaccination in Spain is reviewed, and other potential vaccination strategies in our environment are discussed, such as extending the interval between doses, and administering the last dose in the second year of life, adapting the valid strategy in Spain to the current epidemiological context in order to reduce the prevalence of HB in adulthood.

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.

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.

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.

Hepatitis B in childhood: An update for the paediatrician

Hepatitis B virus (HBV) infection may lead to acute or chronic hepatitis, cirrhosis and hepatocellular carcinoma. The incidence rate of paediatric hepatitis B is 0.2/100,000 to 1.8/100,000 in Canada. Hepatitis B virus infection is acquired largely through mother-to-infant (vertical) or community-based (horizontal) transmission in early childhood, whereas older children are susceptible to HBV infection through exposure to contaminated blood during intravenous drug use or through sexual transmission. Immigrants from endemic areas and some Native Canadian populations are also at a higher risk for HBV infection. Infection with HBV may manifest in three forms: acute self-limited hepatitis, chronic hepatitis or massive hepatic necrosis causing acute liver failure. The identification of HBV infection and the characterization of the disease relies on serological and virological tests. The course of chronic hepatitis B may be classified into three phases: an immunotolerant phase, an active phase and an inactive phase. Current treatment options include interferon-alpha and lamivudine for individuals with elevated serum alanine aminotransferase levels and markers of persistent viral replication. Children with chronic hepatitis B require regular monitoring and age-appropriate lifestyle counselling. Paediatricians are well-positioned to promote vaccination and encourage testing of those who are at risk for hepatitis B. With effective universal vaccination against hepatitis B, this infection could be essentially eliminated in Canada.

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.

Hepatitis B vaccination: The key towards elimination and eradication of hepatitis B

Hepatitis B virus infection is a global health problem. Worldwide, about 360 million people are chronically infected with the virus. They continue to spread the virus to others and are themselves at risk of chronic liver diseases and hepatocellular carcinoma. The infection can now be treated by antivirals or interferons and the transmission route can be interrupted. Nevertheless, the most effective means is to immunize all susceptible individuals, especially young children, with safe and efficacious vaccines. The combined efforts of vaccination, effective treatment and interruption of transmission make elimination of the infection plausible and may eventually lead to eradication of the virus. Because hepatitis B vaccination has a key role in the control of hepatitis B, properties of this vaccine, its effectiveness in pre-exposure and post-exposure settings, duration of protection after vaccination and the need of booster doses are discussed. Mass hepatitis B vaccination in children decreases the carriage of the virus, and the diseases associated with acute and chronic infection, including hepatocellular carcinoma. Challenges that need to be solved to expand mass vaccination, and the strategies towards elimination and eventual eradication of hepatitis B in the world are also discussed.

Evaluation of vaccine coverage for low birth weight infants during the first year of life in a large managed care population

OBJECTIVE

There are few recent population-based assessments of vaccine coverage in premature infants available. This study assesses and compares age- and dose-specific immunization coverage in children of different birth weight categories during the first year of life.

METHODS

We performed a retrospective cohort analysis of computerized vaccination data from a large managed care organization in southern California. The participants were children born between January 1, 1997, and December 31, 2002, and continuously enrolled from birth to at least 12 months of age in the Southern California Kaiser Permanente health plan. We measured age-specific up-to-date and age-appropriate immunization rates according to birth weight (extremely low birth weight: <1000 g; very low birth weight: 1000-1499 g; low birth weight: 1500-2499 g; normal birth weight: >/=2500 g) for 4 vaccines (hepatitis B, diphtheria and tetanus toxoids with pertussis, Haemophilus influenzae type b, and poliovirus) through the first year of life.

RESULTS

We identified 127 833 infants born during the study period and continuously enrolled through the first year of life; 120 048 were normal birth weight infants; 6491 were low birth weight infants; 788 were very low birth weight infants; and 506 were extremely low birth weight infants. Vaccine-specific age-appropriate immunization rates were 3% to 15% lower for low birth weight infants and 17% to 33% lower for extremely low birth weight infants compared with the rates for normal birth weight infants in the first 6 months of life. Extremely low birth weight infants had the lowest age-specific up-to-date immunization levels (5%-31% lower) compared with normal birth weight infants at each age assessed. By 12 months, extremely low birth weight infants still had significantly lower up-to-date levels (87%) compared with very low birth weight, low birth weight, and normal birth weight infants (91%-92%).

CONCLUSIONS

Despite recommendations that lower birth weight infants be vaccinated as the same chronological age as normal birth weight infants, extremely low birth weight and very low birth weight infants are immunized at significantly lower rates relative to low birth weight and normal birth weight infants at 2, 4, and 6 months of age. However, by 12 months of age this finding persists only in extremely low birth weight infants.

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.

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.

Response of preterm newborns to immunization with a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B virus-inactivated polio and Haemophilus influenzae type b vaccine: first experiences and solutions to a serious and sensitive issue

OBJECTIVE

Preterm infants are at increased risk from infections and should be vaccinated at the usual chronological age. The aim of the study was to evaluate the immunogenicity and reactogenicity of a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B virus-inactivated polio and Haemophilus influenzae type b (DTPa-HBV-IPV/Hib) vaccine in preterm infants.

METHODS

In a comparative trial, 94 preterm infants between 24 and 36 weeks (mean +/- SD gestational age: 31.05 +/- 3.45 weeks; mean birth weight: 1420 +/- 600 g) and a control group of 92 full-term infants were enrolled to receive 3 doses of a DTPa-HBV-IPV/Hib vaccine at 2, 4, and 6 months. Immunogenicity was assessed in serum samples that were taken before and 4 weeks after primary vaccination. Evaluation of reactogenicity was based on diary cards.

RESULTS

All preterm (n = 93) and full-term (n = 89) infants who were included in the immunogenicity analysis had seroprotective titers to diphtheria; tetanus; and polio virus types 1, 2, and 3. The immune response to the Hib and hepatitis B components was lower in preterm than in full-term infants: 92.5% versus 97.8% and 93.4% versus 95.2%, respectively. Vaccine response rates for pertussis antigens were >98.9% in both study groups. Although most geometric mean titers were lower in preterm infants, titers were similar for pertussis, a major threat for premature infants. The vaccine was well tolerated, and there were no differences in reactogenicity between groups. Some extremely immature infants experienced transient cardiorespiratory events within the 72 hours after the first vaccination with no clinical repercussion.

CONCLUSIONS

Preterm infants who were immunized with the hexavalent DTPa-HBV-IPV/Hib vaccine at 2, 4, and 6 months displayed good immune response to all antigens. The availability of this vaccine greatly facilitates the vaccination of premature infants.

Experience with hepatitis A and B vaccines

The lengthy history of efforts to understand the pathogenesis and means of preventing and controlling both hepatitis A and B is noteworthy for many exceptional scientific achievements. Among these are the development of vaccines to prevent the spread of infection through induction of active immunity to hepatitis A virus (HAV) and hepatitis B virus (HBV). The first plasma-derived hepatitis B vaccine was licensed in the United States in 1981 and was replaced by recombinant hepatitis B vaccines in 1986 and 1989. Vaccines to prevent HAV infection were licensed in the United States in 1995 and 1996. Subsequently, combination vaccines that included both hepatitis A and B vaccine components, or the hepatitis B component in combination with other commonly administered vaccines, were licensed in the United States. Despite significant reductions in hepatitis-related morbidity and mortality that have resulted from widespread use of these vaccines, vaccine-preventable morbidity and mortality still occur. The purposes of this article are to review clinical trial and other experience with hepatitis A and B vaccines in healthy individuals as well as in those with chronic liver disease, infected with the human immunodeficiency virus, or requiring hemodialysis; describe the impact that these vaccines and national recommendations for vaccination have had on reducing the incidence of HAV and HBV infection; and recommend expansion of these recommendations to include universal vaccination of adults as a means of further reducing the burden of viral hepatitis.

Epidemiology of hepatitis B and hepatitis B virus infection in United States children

Before the era of routine hepatitis B vaccination, an estimated 24,000 children acquired hepatitis B virus (HBV) infection each year in the United States. Childhood hepatitis B immunization has led to significant declines in the incidence and prevalence of HBV infection in U.S. children. Because the greatest burden of hepatitis B is caused by complications of hepatocellular carcinoma and cirrhosis in adults who were infected with HBV as children, most of the benefits of vaccination have yet to be realized. Reaching the goal of eliminating HBV transmission to children likely will require increasing vaccination coverage, ensuring timely administration of postexposure immunoprophylaxis to prevent more perinatal infections, and continued evaluation of the impact of immunization recommendations.

Immunization of preterm and low birth weight infants. American Academy of Pediatrics Committee on Infectious Diseases

Preterm (PT) infants are at increased risk of experiencing complications of vaccine-preventable diseases but are less likely to receive immunizations on time. Medically stable PT and low birth weight (LBW) infants should receive full doses of diphtheria, tetanus, acellular pertussis, Haemophilus influenzae type b, hepatitis B, poliovirus, and pneumococcal conjugate vaccines at a chronologic age consistent with the schedule recommended for full-term infants. Infants with birth weight less than 2000 g may require modification of the timing of hepatitis B immunoprophylaxis depending on maternal hepatitis B surface antigen status. All PT and LBW infants benefit from receiving influenza vaccine beginning at 6 months of age before the beginning of and during the influenza season. All vaccines routinely recommended during infancy are safe for use in PT and LBW infants. The occurrence of mild vaccine-attributable adverse events are similar in both full-term and PT vaccine recipients. Although the immunogenicity of some childhood vaccines may be decreased in the smallest PT infants, antibody concentrations achieved usually are protective.

Immunogenicity of hepatitis B vaccine in preterm and full term infants vaccinated within the first week of life

The immunogenicity of a Hepatitis B vaccine was evaluated in 110 neonates (57 full term and 53 preterm) born to Hepatitis B surface antigen (HBsAg) negative mothers. Three 10 microg doses of recombinant Hepatitis B vaccine were administered: the first dose within the first week of life; the second between 1 and 2 months; and the third at 5-7 months of age. Anti-HBs antibody titres were measured 3 months after the third dose. The seroconversion rate in preterm infants (77%; 95% CI=64.7-87.1) was significantly lower than in full term infants (98%; 95% CI=91.6-99.9) while the mean anti-HBs titres among those infants that did seroconvert was lower in preterm (186.6 mIU ml(-1)) than in full term infants (537.5 mIU ml(-1)). More full term than preterm infants showed titres greater than 100 mIU ml(-1) (71.9 and 41.5%, respectively). We conclude that the administration of a recombinant Hepatitis B vaccine shortly after birth is less immunogenic in preterm infants weighing <1800 g at birth than in full term infants. Currently accepted recommendations for post exposure perinatal prophylaxis may be inadequate to protect preterm infants.

Current update of pediatric hepatitis vaccine use

Vaccines are now available for the prevention of hepatitis A and hepatitis B. In this article, biologics are reviewed with special attention to their use in the pediatric patient. Special attention is paid to issues that developed in 1999. For hepatitis A vaccine, it is the change in US recommendations regarding increased use in higher-risk US locations. For hepatitis B vaccine, it is the concern about toxicity, real or imagined.

Immunogenicity of plasma-derived hepatitis B vaccine in preterm infants

The objective was to determine whether plasma-derived hepatitis B vaccine is immunogenic in preterm appropriate for gestation babies when administered at birth and to compare the immunogenicity between 5 micrograms and 10 micrograms doses of the vaccine in these babies. Fifty preterm neonates (31-36 weeks gestation) were randomized to receive 5 micrograms or 10 micrograms doses of plasma-derived hepatitis B vaccine at birth, with subsequent doses 1 and 6 months later. Serum specimens were obtained a month after each dose of the vaccine and were tested for antibody to hepatitis B surface antigen (anti-HBs). Thirty six babies (gestation 31-36 weeks), 18 from each group competed the study. While 89.2% of the babies seroconverted, 82.1% achieved seroprotective titres of anti-HBS (> 10 mIU/ml). There was no difference between weight, gestational age, age of administration of vaccine and age of estimation of anti-HBs between 5 micrograms and 10 micrograms groups. The difference in the seroprotective rates were not statistically different between the groups (5 micrograms 78.5%; 10 micrograms--85.7%). Although immune response to plasma derived hepatitis B vaccine in preterm babies is suboptimal when the first dose is administered at birth, the full course achieves adequate seroprotective levels.

Safety and immunogenicity of an acellular pertussis vaccine in premature infants

OBJECTIVES

To evaluate the safety and immunogenicity of a two-component acellular pertussis vaccine in preterm infants.

STUDY DESIGN

Fifty preterm infants (25-35 weeks of gestation; mean, 30.8 weeks) and 50 term infants as a control group received a two-component acellular pertussis vaccine irrespective of their biological age and actual weight. Adverse reactions were registered by parents on a diary card and reviewed on each visit. Antibodies against pertussis toxoid (PT) and filamentous hemagglutinin (FHA) were determined with an enzyme-linked immunosorbent assay before the first and after the third vaccination.

RESULTS

The infants of both groups showed an increase in geometric mean titers (GMT) against PT and FHA after vaccination (3 doses). There was a significant difference of antibody concentration between the preterm and the control group. The GMT for PT antibody of the preterm infants was 64. 16 U/L, and for the term infants it was 98.96 U/L. The GMT for FHA was 50.92 U/L in preterm versus 86.02 U/L in the control group. Efficacy of the immunization (more than a fourfold increase of antibody concentration in each infant) was 93.5% in the preterm group with respect to PT and 82.6% with respect to FHA. The incidence of adverse reactions was low and comparable in both study groups.

CONCLUSION

Immunization with an acellular pertussis vaccine is safe for preterm infants. The immune response is significantly lower compared with a control group of term infants, but efficacy is high.