Booster Vaccination In Children Research Articles

Long-term immunoprotection after live attenuated measles-mumps-rubella booster vaccination in children with juvenile idiopathic arthritis

IntroductionVaccines, especially live attenuated vaccines, in children with JIA pose a great challenge due to both potential lower immunogenicity and safety as a result of immunosuppressive treatment. For many years, in the Netherlands, JIA patients receive a measles-mumps-rubella (MMR) booster vaccine at the age of nine years as part of the national immunization program. ObjectivesTo study long-term humoral immunoprotection in a large cohort of JIA patients who received the MMR booster vaccine while being treated with immunomodulatory therapies at the Wilhelmina Children’s Hospital in Utrecht, the Netherlands. MethodsMMR-specific IgG antibody concentrations in stored serum samples of vaccinated JIA patients were determined with chemiluminescent microparticle immunoassays (CMIA). Samples were analyzed five years after MMR booster vaccination and at last available follow-up visit using both crude and adjusted analyses. Additional clinical data were collected from electronic medical records. ResultsIn total, 236 samples from 182 patients were analyzed, including 67 samples that were available five years post-vaccination, and an additional 169 samples available from last visits with a median duration after vaccination of 6.9 years (IQR: 2.8–8.8). Twenty-eight patients were using biologic disease-modifying antirheumatic drugs (bDMARDS) of whom 96% anti-TNF agents and 4% tocilizumab. Percentages of protective antibody levels against measles after five years were significantly lower for patients who used bDMARD therapy at vaccination compared to patients who did not: 60% versus 86% (P = 0.03). For mumps (80% versus 94%) and rubella (60% versus 83%) this difference did not reach statistical significance (P = 0.11 and P = 0.07, respectively). Antibody levels post-vaccination decreased over time, albeit not significantly different between bDMARD users and non-bDMARD users. ConclusionThe MMR booster vaccine demonstrated long-term immunogenicity in the majority of children with JIA from a large cohort, although lower percentages of protective measles antibody levels were observed in bDMARD users. Hence, it might be indicated to measure antibody levels at least five years after MMR booster vaccination in the latter group and advice an extra booster accordingly.

High antibody levels and reduced cellular response in children up to one year after SARS-CoV-2 infection

The COVID-19 course and immunity differ in children and adults. We analyzed immune response dynamics in 28 families up to 12 months after mild or asymptomatic infection. Unlike adults, the initial response is plasmablast-driven in children. Four months after infection, children show an enhanced specific antibody response and lower but detectable spike 1 protein (S1)-specific B and T cell responses than their parents. While specific antibodies decline, neutralizing antibody activity and breadth increase in both groups. The frequencies of S1-specific B and T cell responses remain stable. However, in children, one year after infection, an increase in the S1-specific IgA class switch and the expression of CD27 on S1-specific B cells and T cell maturation are observed. These results, together with the enhanced neutralizing potential and breadth of the specific antibodies, suggest a progressive maturation of the S1-specific immune response. Hence, the immune response in children persists over 12 months but dynamically changes in quality, with progressive neutralizing, breadth, and memory maturation. This implies a benefit for booster vaccination in children to consolidate memory formation.

Behavioral Intention and Its Predictors toward COVID-19 Booster Vaccination among Chinese Parents: Applying Two Behavioral Theories.

The booster vaccination of COVID-19 is being implemented in most parts of the world. This study used behavioral psychology to investigate the predictors of parents’ intentions regarding the COVID-19 booster vaccination for their children. This is a cross-sectional study with a self-designed questionnaire based on two behavioral theories—protective motivation theory (PMT) and theory of planned behavior (TPB). A stratified multi-stage sampling procedure was conducted in Nanjing, China, and multivariable regression analyses were applied to examine the parents’ intentions. The intention rate was 87.3%. The response efficacy (ORa = 2.238, 95% CI: 1.360–3.682) and response cost (ORa = 0.484, 95% CI: 0.319–0.732) in the PMT, were significant psychological predictors of parents’ intentions, and so were the attitude (ORa = 2.619, 95% CI: 1.480–4.636) and behavioral control (ORa = 3.743, 95% CI: 2.165–6.471) in the TPB. The findings of crucial independent predictors in the PMT and TPB constructs inform the evidence-based formulation and implementation of strategies for booster vaccination in children.

Long-Term Immunogenicity upon Pertussis Booster Vaccination in Young Adults and Children in Relation to Priming Vaccinations in Infancy.

Booster vaccinations for pertussis are advised in many countries during childhood or adulthood. In a phase IV longitudinal interventional study, we assessed long-term immunity following an extra pertussis booster vaccination in children and adults. Children (9 years of age) were primed in infancy with either the Dutch whole cell pertussis (wP) vaccine (n = 49) or acellular pertussis (aP) vaccines (n = 59), and all children received a preschool aP booster. Adults (25–29 years, n = 86) were wP-primed in infancy and did not receive a preschool booster. All were followed-up for approximately 6 years. After the additional booster, antibody responses to pertussis were more heterogeneous but generally higher in adults compared with children, and additional modelling showed that antibody concentrations remained higher for at least a decade. Serologic parameters indicative of recent pertussis infection were more often found in aP-primed children (12%) compared with wP-primed individuals (2%) (p = 0.052). This suggests that the aP booster vaccination in aP-primed children offers less long-term protection against pertussis infection and consequently against transmission. Together, these data show that aP priming in combination with aP boosting may not be sufficient to prevent circulation and transmission, while wP-primed adults may benefit from enhanced long-lasting immunity.

Corrigendum to ‘Responses to an acellular pertussis booster vaccination in children, adolescents, and young and older adults: A collaborative study in Finland, the Netherlands, and the United Kingdom’

Acknowledgements We thank all participants of the study and we acknowledge the work of all individuals at the Oxford Vaccine Group, the Turku University group, the Dutch Spaarne Hospital and RIVM who have undertaken the work of the BERT study including the administrative staff, play assistants, clinical research nurses, clinical research fellows, laboratory staff and members of the IT team. In particular, we acknowledge Jacqueline Zonneveld and Greetje van Asselts at the Spaarne Gasthuis Hospital, Hoofddorp, the Netherlands for their help in the management of clinical data and performing home visits. We are also grateful to Inge Pronk and Eleonora Lambert, who both work at the Centre for Infectious Disease Control, RIVM for their assistance in clinical trial management. PERISCOPE has received funding from the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement No 115910. This Joint Undertaking receives support from the European Union's Horizon 2020 research and innovation programme and EFPIA and BMGF. DFK receives salary for support from the NIHR Oxford Biomedical Research Centre. Responses to an acellular pertussis booster vaccination in children, adolescents, and young and older adults: A collaborative study in Finland, the Netherlands, and the United KingdomAcellular pertussis booster vaccination induces significant serum IgG responses to pertussis antigens across the age range which are not uniformly less in older adults. Acellular boosters could be considered for older adults to reduce the health and economic burden of pertussis. Full-Text PDF Open Access

Seroprevalence of anti-HBs antibodies and the need for booster vaccination in children under 5 years of age born to HBsAg-negative mothers

Objective: To determine the proportion of HBV surface antigen (anti-HBs) antibody positive children under five years of age born to HBsAg-negative mothers and to analyze the possible related factors following implementation of a hepatitis B vaccination program for infants in Indonesia 22 years ago. Methods: Blood samples were taken from children under five years of age born to HBsAg-negative mothers who have completed primary vaccination series. Anti-HBs antibodies were determined by using rapid test. Data of age, gender, nutritional status, vaccination timing or vaccination compliance, and booster vaccination were collected from vaccination card. Results: Ninety children were enrolled, consisting of 47 females and 43 males with a mean age of 2.3 years. Twenty two (24.4%) children received booster vaccine between 18 and 24 months and 55 (61.1%) were anti-HBs positive. Among factors of age, gender, nutritional status, compliance to vaccination and booster vaccine, only administration of booster vaccine was significantly associated with anti-HBs status (OR 5.45, 95% CI 1.45, 20.52). Children who received booster vaccine at age of 18-24 months were 5.45 times more likely to be anti-HBs positive than that of children who did not receive booster vaccine. Conclusions: Booster vaccine rate is low among children under 5 years of age but is associated with anti-HBs positivity. Booster vaccination may be required to improve anti-HBs seropositivity.

Adequate Responses to an Acellular Pertussis Booster Vaccination in Children, Adolescents, and Young and Older Adults: A Collaborative Study in Finland, the Netherlands, and the United Kingdom

Background: Pertussis can lead to serious disease and even death in infants. In addition older adults and patients with chronic diseases are more vulnerable to complications. In high-income countries, priming vaccination in infancy is usually undertaken using acellular pertussis vaccines. There is a significant between-country variation in the use of booster vaccinations which are administered at different ages and to different target populations. We investigated the effect of age on the response to acellular pertussis booster vaccination in three European countries. Methods: In total 379 participants, divided between four age groups - children (7-10y), adolescents (11-15y), young adults (20-34y), and older adults (60-70y) - received a pertussis toxoid, filamentous haemagglutinin, and pertactin containing booster vaccine. Serum IgG and IgA antibody concentrations to pertussis vaccine antigens at day 0, day 28, and one year were measured with a multiplex immunoassay. Findings: Participants from all four age groups showed high IgG antibodies to pertussis toxin at day 28. IgG antibody concentrations at 28 days and one year postvaccination were comparable between the age groups, but IgA concentrations showed an increase of antibody concentrations with age at all timepoints. Interpretation: Acellular pertussis booster vaccination induces comparable serological responses in older adults as younger age groups and could be considered for older adults in order to increase their protection. Trial Registration: The trial was registered at the EU Clinical Trial database (EudraCT number 2016-003678-42). Funding: PERISCOPE has received funding from the Innovative Medicines Initiative2 Joint Undertaking under grant agreement No 115910. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme, EFPIA and BMGF. Declaration of Interests: None of the authors received payment or service from a third part at any time, nor does anyone have a financial relationship with entities in the bio-medical arena. None of the authors have any patents relevant to the work. MVP is a member of the Portuguese National Immunisation Technical Advisory Group (Comissao Tecnica de Vacinacao da Direccao Geral de Saude). Ethics Approval Statement: The trial was approved by the Medical Research Ethics Committees United (MEC-U, NL60807.100.17-R17.039) in the Netherlands, the South Central - Hampshire B Research Ethics Committee (REC, 19/SC/0368) in the UK, and the MREC UTU (ETMK Dnro: 129/1800/2017) in Finland. Written informed consent was obtained from all adult participants, and parents or legal guardian of minors, at the start of the study.

Immunogenicity, safety, and reactogenicity of combined reduced-antigen-content diphtheria-tetanus-acellular pertussis vaccine administered as a booster vaccine dose in healthy Russian participants: a phase III, open-label study

ABSTRACT As vaccine-induced immunity and protection following natural pertussis infection wane over time, adults and adolescents may develop pertussis and become transmitters to unprotected infants. In Russia, diphtheria and tetanus but not pertussis-containing vaccines are registered for older children, adolescents, or adults. The reduced-antigen-content diphtheria toxoid, tetanus toxoid, and acellular pertussis (dTpa) vaccine (Boostrix, GSK) was developed for booster vaccination of children ≥4 years of age, adolescents, and adults. A phase III, open-label, non-randomized study was performed in eight centers in Russia between January and July 2018. The objective of this study was to assess immunogenicity, reactogenicity and safety of a single dose of dTpa vaccine in healthy Russian participants ≥4 years of age (age categories 4–9 years, 10–17 years, 18–64 years, and ≥65 years). At 1 month post-booster vaccination, across all age groups, >99.0% of participants were seroprotected against diphtheria and tetanus and >96.0% of participants were seropositive for anti-pertussis antibodies. For all antibodies across all age groups, antibody GMCs increased from pre- to 1 month post-booster vaccination and booster responses to diphtheria (in 71.5% of participants), tetanus (85.3%), and pertussis antigens (≥85.6%) were observed. One serious adverse event that was not causally related to the study vaccine was reported. No fatal cases were reported throughout the study period. In conclusion, administration of the dTpa vaccine as a booster dose in healthy Russian participants induced a robust immune response to all vaccine antigens and was generally well tolerated across all age groups.

Strategies for hepatitis B booster vaccination among children: an 8-year prospective cohort study

ABSTRACT Debate continues regarding the need for a booster vaccination in children who received a universal infant hepatitis B virus (HBV) vaccination. The aim was to explore the need and the strategies for the booster HBV vaccination. 8-year prospective cohort study was conducted among children aged 5–15 years in 2009–2010 in Zhejiang Province. The participants were divided into groups A (<0.1 mIU/mL), B (0.1 to < 1 mIU/mL) and C (1 to <10 mIU/mL) according to the pre-booster anti-HBs antibody levels. 5 μg (group I), 10 μg (group II), 20 μg hepatitis B vaccines (group III) or 5 μg hepatitis A and B (HAB) vaccines (group IV) with 0-1-6-month schedule were randomly administered to children negative for all markers. Blood samples were collected at baseline HBV marker testing, 1 month after the first dose, 1 month, 1 year, 5 years and 8 years after the third dose. Among 4170 children, 2326 (55.8%) were negative for all HBV markers. Group II showed the highest seropositive rates of 92.8%, 99.7%, 97.6%, 90.3% and 83.4% with GMTs of 4194.5 mIU/ml, 4163.9 mIU/ml, 466.9 mIU/ml, 190.6 mIU/ml, 122.6 mIU/ml from 1 month after dose 1 to 8 years after dose 3, respectively (P < .01). Participants in group C showed seropositive rates of 98.9%, 99.9%, 99.5%, 95.5%, 92.8% after the revaccination with GMTs of 6519.6 mIU/ml, 5267.4 mIU/ml, 547.1 mIU/ml, 249.5 mIU/ml, 155.3 mIU/ml, respectively, higher than group A and B (P < .001), except 1 month after the third dose. The 10 μg of HBV vaccine with a 0-1-6-month booster regimen may elicit robust responses and persist for 8 years or longer. Additionally, 1-dose revaccination maybe suitable for children with 1 to < 10 mIU/ml anti-HBs titers.

Safety of two doses of an inactivated hepatitis a vaccine given 6 months apart in healthy toddlers, children, and adolescents aged 12 months to 15 years in China: a phase IV study

ABSTRACTHepatitis A is a vaccine-preventable infection caused by the HA virus (HAV) with transitional to intermediate endemicity in China. An inactivated vaccine first licensed in China in 2010 (Avaxim® 80U Pediatric) is indicated for primary and booster vaccination in children from 12 months to 15 years of age. This Phase IV, open-label, single-arm trial supported licensure in pediatric age groups in China. A total of 355 healthy infants and toddlers (< 2 years of age), children (2 to 11 years of age), and adolescents (≥ 12 years of age) were enrolled to receive two doses of intramuscular HA vaccine, separated by 6 months. Participants were split into Group 1 (infants and toddlers: N = 270) and Group 2 (children and adolescents: N = 85). Safety was assessed by solicited injection site and systemic adverse events (AEs) for 7 days and unsolicited AEs for 30 days after each vaccination. Serious AEs (SAEs) were collected throughout. Immunogenicity was not assessed. Analyses were descriptive. Both vaccinations were very well tolerated in each group. The incidence of solicited injection site reactions was lower in Group 1 (17.9%) than Group 2 (33.3%) and for solicited systemic reactions was similar for each group. The incidence of unsolicited AEs in Group 1 was 6.3% and none in Group 2. For solicited and unsolicited AEs the incidence was slightly higher after the first vaccination. There were no SAEs. Overall, the good safety profile of this pediatric HA vaccine was confirmed in infants, toddlers, children, and adolescents aged 12 months to 15 years in China.

Immunogenicity of Pertussis Booster Vaccination in Children and Adolescents with Inflammatory Bowel Disease

There are limited data on antibody response to vaccination in patients with inflammatory bowel disease (IBD). In this study, we aimed to assess the immunogenicity of a booster dose of pertussis vaccine in pediatric patients with IBD and to compare their response with healthy controls. We performed a multicenter, prospective, and controlled trial. Eligible for inclusion were children and adolescents (11-18 year olds), with no history of pertussis booster immunization after the age of 6 years or history of pertussis. Study population was divided into 4 groups: patients with IBD receiving no immunosuppressive therapy (group 1), those on thiopurines only (group 2), those on thiopurines and TNF-α agents (group 3), and healthy controls (group 4). Patients and controls received 1 dose of pertussis vaccine intramuscularly and were asked to record adverse effects for 3 days after vaccination. The primary outcome measure was adequate vaccine response, defined as the concentration of anti-Bordetella pertussis antibodies >11 μg/mL, measured between 4 and 8 weeks after the vaccination. In total, 138 subjects (111 patients and 27 controls) were enrolled in the study. Rates of adequate vaccine response did not differ among the 4 study groups (P = 0.11). Moreover, those patients with IBD who were on immunosuppressive therapy did not differ from those who were not (90.6% versus 88.2%, P = 0.37). No serious adverse effects in relation to the administration of vaccine were noted. Booster dose of pertussis vaccine was immunogenic and safe in pediatric patients with IBD.

Results of Booster Vaccination in Children with Primary Vaccine Failure after Initial Varicella Vaccination

In October 2014, the varicella vaccination policy in Japan was changed from a single voluntary inoculation to two routine inoculations. This paper reports the results of booster vaccination in children who did not show seroconversion after initial vaccination (i.e., primary vaccine failure : PVF) over a 7-year period prior to the introduction of routine varicella vaccination. Between November 2007 and May 2014, 273 healthy children aged between 1.1 and 14.5 years (median : 1.7 years) underwent varicella vaccination. Before and 4 to 6 weeks after vaccination, the antibody titers were measured using an immune adherence hemagglutination (IAHA) assay and a glycoprotein-based enzyme-linked immunosorbent assay (gpELISA). In addition, side reactions were examined during the four-week period after vaccination. Children who did not show IAHA seroconversion (PVF) were recommended to receive a booster vaccination, and the measurement of antibody titers and an assessment of side reactions were performed after the booster dose. In May 2015, a questionnaire was mailed to each of the 273 participants to investigate whether they had developed varicella and/or herpes zoster after vaccination. After initial vaccination, the IAHA seroconversion rate was 75% and the mean antibody titer (Log2) with seroconversion was 4.7, while the gpELISA seroconversion rate was 84% and the mean antibody titer (Log10) with seroconversion was 2.4. Among children with PVF, 54 received booster vaccination within 81 to 714 days (median : 139 days) after the initial vaccination. After booster vaccination, the IAHA seroconversion rate was 98% and the mean antibody titer (Log2) with seroconversion was 5.8. Both the seroconversion rate and the antibody titer were higher compared with the values after the initial vaccination (p < 0.01). After booster vaccination, the gpELISA seropositive rate was 100% and the mean positive antibody titer (Log 10) was 3.6 ; similar results were obtained for the IAHA assay, with a significantly higher, antibody response than that after the initial vaccination (p < 0.01). Side reactions were generally minor, including fever (≥ 37.5 degrees C), rash at the injection site, and rash at other sites. There were no significant differences in the incidences of side reactions between the initial and booster vaccinations. A total of 185 participants responded to the questionnaire (response rate : 68%), and the period between receiving the initial vaccination and their response to the questionnaire ranged from 1.0 to 7.5 years (median : 4.0 years). The prevalence of breakthrough varicella after the initial vaccination was 17% among seroconverters who did not receive booster vaccination and 14% among non-seroconverters who received booster vaccination, showing no significant difference between the two groups. In conclusion, there are no safety issues regarding the administration of a booster vaccination to children with PVF after an initial varicella vaccination, and,a good antibody response can be expected.

Evaluation of a new syringe presentation of reduced-antigen content diphtheria, tetanus, and acellular pertussis vaccine in healthy adolescents - A single blind randomized trial

Reduced-antigen-content diphtheria-tetanus-acellular pertussis (dTpa) vaccine, Boostrix™, is indicated for booster vaccination of children, adolescents and adults. The original prefilled disposable dTpa syringe presentation was recently replaced by another prefilled-syringe presentation with latex-free tip-caps and plunger-stoppers. 671 healthy adolescents aged 10–15 years who had previously received 5 or 6 previous DT(P)/dT(pa) vaccine doses, were randomized (1:1) to receive dTpa booster, injected using the new (dTpa-new) or previous syringe (dTpa-previous) presentations. Immunogenicity was assessed before and 1-month post-booster vaccination; safety/reactogenicity were assessed during 31-days post-vaccination. Non-inferiority of dTpa-new versus dTpa-previous was demonstrated for all antigens (ULs 95% CIs for GMC ratios ranged between 1.03-1.13). 1-month post-booster, immune responses were in similar ranges for all antigens with both syringe presentations. dTpa delivered using either syringe presentation was well-tolerated. These clinical results complement the technical data and support the use of the new syringe presentation to deliver the dTpa vaccine.

Prevalence and socio-demographic factors associated with non-protective immunity against tetanus among high school adolescents girls in Nigeria

BackgroundThe low uptake of tetanus vaccine and its resultant high burden of tetanus in Nigeria suggest the need to improve routine and booster vaccination in children and adolescents. However, epidemiological evidence for vaccination in the adolescent age group needed for effective strategy and policy formulation is lacking. This study was carried out to determine the prevalence of protective immunity against tetanus and to identify risk factors for non-protective immunity among schooling adolescents.MethodsUsing a three-stage sampling technique, 851 female adolescents were randomly selected from secondary schools in Ibadan, Nigeria. A pre-tested questionnaire was used to obtain data on demographic and socio-economic characteristics and history of tetanus vaccination. An immuno-chromatographic rapid test kit, “Tetanos Quick Stick” was used to test specific anti-tetanus antibody protective level in venous blood samples. Descriptive statistics, Chi-square and logistic regression analyses were done with level of significance set at p = 0.05.ResultsMean age of participants was 14.3 ± 1.9 years. Seroprevalence of protective immunity against tetanus was 38.1% and it significantly decreased with increasing age. More adolescents in public (65.4%) than private (44.7%) schools had non-protective level of immunity. A significantly increasing trend in the risk of non-protective immunity was observed with decreasing level of mothers’ education. Also, the Odds of non-protective level of immunity was significantly higher in public than private schools (OR = 2.14; 95% CI =1.39, 3.20) but lower among adolescents who had history of recent tetanus toxoid injection than those who did not (OR = 0.11 95% CI = 0.09, 0.22). However, no significant association was found between protective immunity against tetanus and parents’ marital status as well as family size.ConclusionProtective immunity against tetanus among female adolescents was poor, more so in public schools and those who had not received vaccination a year prior to the study. Policy-makers need to consider the inclusion of immunization against tetanus in the school health programme.

Juvenile Idiopathic Arthritis and Live Virus Vaccines

Juvenile Idiopathic Arthritis and Live Virus Vaccines

Enhanced memory B-cell immune responses after a second acellular pertussis booster vaccination in children 9 years of age

Whooping cough has made its comeback and the incidence of pertussis in countries with widespread pertussis vaccination is most prominent in individuals above 9 years of age. To control the burden of infection, several countries already introduced acellular pertussis (aP) booster vaccination in adolescents and/or adults. However, antibody levels wane rapidly after vaccination even at older age. In this longitudinal study we investigated the effect of a second aP booster on the pertussis-specific memory B-cell immunity in children 9 years of age that have previously been vaccinated according to the national immunization program. Longitudinal blood samples were taken before, one month and one year after the booster. Purified B-cells were polyclonally stimulated and frequencies of memory B-cells were identified by ELISPOT-assays specific for various pertussis antigens. In addition, IgG levels and avidity indices were measured with fluorescent bead-based multiplex immunoassays. Starting with low pertussis-specific antibody and memory B-cell levels, a typical booster response was measured at one month after vaccination with increased antibody and memory B-cell responses. Although these responses declined slightly after one year, they substantially exceeded pre-booster levels and the avidity indices of the anti-pertussis antibodies remained high. Furthermore, high numbers of pertussis-specific memory B-cells at one-month post-booster correlate quite reliably with the corresponding high antibody response at one-year follow-up. In conclusion, booster vaccination in children 9 years of age induced an enhanced pertussis-specific memory immune response that sustained at least for one year. Therefore, this study supports the introduction of booster vaccination in older age groups.

Hepatitis B Immunity and Response to Booster Vaccination in Children With Inflammatory Bowel Disease Treated With Infliximab

Hepatitis B virus (HBV) reactivation has been described in patients treated with infliximab for inflammatory bowel disease (IBD). This has resulted in a "black box" warning. Although universal vaccination against hepatitis B was implemented in the United States in 1991, up to 10% of vaccine recipients fail to respond with adequate anti-hepatitis B surface antibodies (anti-HBs) levels after a primary series of vaccinations. In addition, anti-HBs levels are expected to decline with time. The objectives of this study were to determine HBV immunity in children with IBD on infliximab therapy and to determine response to a booster dose of the HBV vaccine in patients who were found to be non-immune. This was a prospective cross-sectional, single-center study that included 100 pediatric IBD patients on infliximab. Serologic specimens were tested for hepatitis B surface antigen (HBsAg), hepatitis B core antibody (anti-HBc), and anti-HBs. Patients with an anti-HBs level ≥10 mIU/ml were considered to be immune. One booster dose was given to non-immune patients and a serum sample was collected after 4 weeks to assess the presence of anamnestic response (anti-HBs level ≥10 mIU/ml after booster). The mean age of the patients was 17.9 (±4.0) years. None of the patients were positive for HBsAg or anti-HBc. In all, 87 patients were vaccinated against HBV and 49/87 (56%) had immunity to HBV as defined by anti-HBs level ≥10 mIU/ml. The mean concentration of anti-HBs levels in immune patients was 295.6 (±350.6) mIU/ml. Older age, lower albumin levels, and the presence of pancolitis were associated with the absence of protective antibodies; however, infliximab dose, frequency, duration, and the concurrent use of immunomodulators were not significantly different between immune and non-immune patients. Thirty-four patients received booster immunization and 26/34 (76%) had an anamnestic response. Interestingly, non-responders were given infliximab with higher frequency (every 5.9 ± 1.2 weeks vs. every 7.1 ± 1.8 weeks, P=0.01). Overall, 75/87 (86%) of previously immunized patients were considered immune against HBV infection. In pediatric IBD patients seen at a large, urban tertiary care facility in the United States, a significant minority (13%) have not been vaccinated against HBV. Nearly one-half of all patients (and 44% of previously vaccinated patients) did not have protective anti-HBs levels. Moreover, of those previously vaccinated, a significant minority (14%) appear at risk for HBV because protective anti-HBs levels were absent and could not be elicited through booster immunization. Given the high risk for severe HBV infection in this group, efforts should be made to screen for HBV immunity at the time of IBD diagnosis. Booster immunization should be considered in patients without protective antibodies.

Humoral immune response after post‐chemotherapy booster diphtheria–tetanus–pertussis vaccine in pediatric oncology patients

The role of post-chemotherapy booster vaccination in pediatric oncology children remains to be established. In this randomized controlled study, we studied the effect of immune responses to diphtheria-tetanus-pertussis (DTP) booster vaccination in children 6 months after completing chemotherapy. Children 1-18 years old with chemotherapy completed for 6 months (baseline) were eligible. Subjects were randomized into vaccine and control group. In the former, three doses of DTP vaccine (Aventis Pasteur Inc., Lyon, France) were administered. IgG antibody titers against diphtheria, tetanus, pertussis, hepatitis B, measles, mumps, and rubella antibodies were measured serially in vaccine and control groups. Subsets of circulating lymphocytes (CD3(+), CD4(+), CD8(+), CD19(+), and CD16/56(+)) were quantified by flow cytometry using fluorescence-labeled monoclonal antibodies. Fifty-six children (28 vaccinees; 28 controls) were enrolled. Protective antibody levels against diphtheria, tetanus, pertussis were found at baseline in 83.6%, 96.5%, 96.1% of them respectively. After three doses of DTP, all vaccinees demonstrated a sustain rise in antibody levels and the antibody titers were significantly higher than control group. 35.8% of subjects were susceptible to measles mumps and rubella infection and 69% showed anti-HBs antibody titer less than protective level up to 18 months after stopping chemotherapy. Post-chemotherapy booster vaccinations produced a strong and sustained effect in humoral immunity against vaccine-preventable infectious diseases.

Pertussis Booster Vaccination in HIV-Infected Children Receiving Highly Active Antiretroviral Therapy

Our goal was to evaluate the immunogenicity and safety of pertussis booster vaccination in children infected with HIV on highly active antiretroviral therapy (HAART). HIV-infected children on stable HAART for > or = 3 months with plasma HIV-RNA concentrations of < 30,000 to 60,000 copies per mL who previously received > or = 4 doses of diphtheria-tetanus-pertussis (DTP)-containing vaccine were eligible. Diphtheria-tetanus-acellular pertussis (DTaP) vaccine was administered to subjects 2 to < 7 years old who had 4 previous DTP-containing vaccines, subjects 2 to < 7 years old who had > or = 5 previous DTP-containing vaccines and negative tetanus antibody, and subjects > or = 7 to < or = 13 years old who had negative tetanus antibody. Pertussis toxin and filamentous hemagglutinin antibodies were measured before and 8, 24, and 72 weeks after DTaP vaccine. Ninety-two subjects received DTaP vaccine and met criteria for analysis. Antibody concentrations were low at entry: pertussis toxin geometric mean concentration at 4.8 enzyme-linked immunosorbent assay units (EU) per mL and filamentous hemagglutinin geometric mean concentration at 4.1 EU/mL. Pertussis toxin and filamentous hemagglutinin geometric mean concentrations rose to 22.3 and 77.0 EU/mL, respectively, 8 weeks after the study DTaP vaccine. Antibody concentrations fell by 24 weeks after vaccination but remained higher than before vaccination. Predictors of response 8 weeks after DTaP vaccine included the concentration of homologous antibody, lower HIV-RNA level, and higher CD4 percentage at entry. One vaccinated subject experienced erythema and induration of > or = 25 mm. A DTaP vaccine booster was well tolerated by children on HAART and induced increases in antibodies. Antibody concentrations after vaccination were lower than those reported in populations uninfected by HIV. Although comparison among studies must be made with caution, these data suggest that children infected with HIV may be deficient in immunologic memory from previous DTP-containing vaccination and/or that immune reconstitution with HAART may be incomplete for pertussis antigens.

Reactogenicity and immunogenicity of reduced antigen content diphtheria–tetanus–acellular pertussis vaccine (dTpa) administered as a booster to 4–6 year-old children primed with four doses of whole-cell pertussis vaccine

A trial to compare the reactogenicity and immunogenicity of a reduced antigen content diphtheria–tetanus–acellular pertussis (dTpa) vaccine with diphtheria–tetanus–whole-cell pertussis (DTPw) vaccine was conducted in Thailand. Three hundred and thirty children aged 4–6 years, primed with four doses of DTPw, received a single injection of either dTpa or DTPw. There was a significantly lower incidence of local and general reactions following dTpa than DTPw ( P<0.001). One month after vaccination, 99.4 and 100% of all subjects had protective anti-diphtheria and -tetanus titers, respectively. The vaccine response rate to pertussis antigens was similar in both groups, with 96.9% versus 92.5% for anti-pertussis toxin (PT), 96.9% versus 97.5% for anti-filamentous hemagglutinin (FHA) and 95.1% versus 90.8% for anti-pertactin (PRN) in the dTpa and DTPw groups, respectively. For anti-BPT, the vaccine response in the dTpa group was 29.6% versus 94.4% for DTPw. In conclusion, the dTpa vaccine was as immunogenic and significantly better tolerated than DTPw. The new dTpa vaccine could improve coverage for routine booster vaccination in children and provide a good replacement for DTP vaccines at 4–6 years of age.