Immunogenicity and safety of a low-dose diphtheria, tetanus and acellular pertussis combination vaccine with either inactivated or oral polio vaccine as a pre-school booster in UK children

Safety and Clinical Benefits of Adacel® and Adacel®-Polio Vaccination in Pregnancy: A Structured Literature Review

Vaccination in pregnancy using a tetanus toxoid, reduced dose diphtheria toxoid, and reduced dose acellular pertussis (Tdap) vaccine is important for prevention of severe pertussis disease in young infants. The objectives of this systematic literature review were to search for original research studies evaluating the vaccine effectiveness, immunogenicity, and safety of Adacel®/Adacel-Polio® used during pregnancy to prevent pertussis disease in young infants. Medical databases used included EMBASE, BIOSIS Previews, and Chemical Abstracts, with search terms related to pregnancy, vaccines/immunization, safety, pertussis, effectiveness/efficacy, and immune response; other potentially eligible reports were included where applicable. Search results were restricted to literature published from 1 January 1995 to 26 July 2021. A total of 2021 articles and 4 other reports were identified for primary review. A total of 49 publications qualified for inclusion after primary and secondary reviews. Effectiveness studies of Adacel or Adacel-Polio given in pregnancy consistently showed high levels of protection from pertussis disease in the newborn (vaccine effectiveness: 91-93%). In immunogenicity studies, the response in pregnant women was consistent with that of non-pregnant women. Infants of mothers vaccinated with Adacel or Adacel-Polio in pregnancy had higher anti-pertussis antibody levels at birth and at 2 months of age compared to infants born to women vaccinated with comparator vaccines, placebo, or those not vaccinated during pregnancy. There was evidence of a slightly decreased response to primary pertussis vaccination in infants of mothers vaccinated with Adacel or Adacel-Polio, but this was not thought to be clinically significant. In safety studies, Adacel or Adacel-Polio vaccination was well tolerated by pregnant woman and not associated with pregnancy, postpartum, or neonatal complications. In conclusion, Adacel or Adacel-Polio vaccination in pregnancy is highly effective in protecting young infants from pertussis disease, with a favorable safety profile for both pregnant women and their infants.

Evaluation methods for vaccination campaigns on college campuses: A scoping review

Background

Vaccinations are successful, cost-effective tools to prevent the spread of certain infectious diseases. Many colleges conduct vaccination campaigns on their campuses for various vaccine-preventable diseases, including measles, mumps, influenza, HPV, and most recently, for SARS-CoV-2, the virus responsible for COVID-19. Implementing these campaigns requires substantial effort and understanding their effectiveness is an important factor in justifying these programs.

Aim

This scoping review aims to identify, review, and summarize existing evaluation methods for vaccination campaigns on college campuses in order to provide evaluation guidance for institutions planning future vaccination campaigns.

Methods

Publications that focused on vaccination campaigns on college campuses for students and/or faculty and staff and described their evaluation methods were included in our analysis. A systematic search of the literature identified 2,101 articles. After duplicates were removed, titles and abstracts were screened, and references searched, 43 articles were identified for full-text review. Sixteen articles provided evaluation information and were systematically reviewed.

Results

Interventions targeted a variety of vaccine-preventable diseases, with the majority either aiming to increase HPV vaccine uptake or vaccinate against meningococcal serogroups. Most studies reported on campaigns that included both educational activities and provided vaccinations. Evaluation methods varied widely. Some studies measured vaccine-related knowledge and attitudes. Vaccine uptake was most commonly measured as a simple count of doses administered.

Conclusions

College campus vaccination campaigns are evaluated in multiple ways, with little consistency in how the effectiveness of campaigns are measured. There is a need to develop clear evaluation methods for college vaccination programs, especially how to calculate vaccination rates associated with these efforts.

A combined DTaP-IPV vaccine (Tetraxim®/Tetravac®) used as school-entry booster: a review of more than 20 years of clinical and post-marketing experience

INTRODUCTION

Routine infant primary series and toddler booster vaccination are associated with waning of antibody levels over time, which can lead to an increased incidence of vaccine-preventable diseases. A diphtheria-tetanus-pertussis (DTP) booster vaccination at school-entry (aged 4-7 years) allows continued protection against these diseases and is included in many national immunization programs.

AREAS COVERED

The available immunogenicity and safety data from 6 clinical studies of a diphtheria-tetanus-acellular pertussis-inactivated poliovirus vaccine (DTaP-IPV [Tetraxim®]) used as a school-entry booster vaccination were identified using a PubMed search or on file at Sanofi. The studies spanned a 15-year period (1995-2010) and were performed in different populations using different study designs, so all data were reviewed descriptively (no meta-analyses were conducted). Additionally, post-marketing experience was reviewed.

EXPERT OPINION

Each vaccine antigen is highly immunogenic, and the safety profile of the vaccine is satisfactory. Post-marketing evaluations have shown the effectiveness of a school-age booster, particularly against increased pertussis disease incidence around the time of school entry and the associated risk of spreading the disease through contact with younger vulnerable infants. School-entry provides an ideal opportunity to implement DTaP-IPV vaccination to close the gap between waning immunity from the previous infant/toddler vaccination and future adolescent vaccination.

Post-Marketing Surveillance of Tetravalent Diphtheria-Tetanus-Acellular Pertussis and Inactivated Poliovirus (DTaP-IPV) Vaccine in South Korea, 2009 to 2015

Introduction

TETRAXIM™ (Sanofi), a combined diphtheria, tetanus, acellular pertussis, and inactivated poliovirus (DTaP-IPV) vaccine, has been licensed in South Korea since 2009. In accordance with the Ministry of Food and Drug Safety regulations, this post-marketing surveillance (PMS) study evaluated the safety of the DTaP-IPV vaccine in real-world clinical practice in infants and children who received it as either a part of the three-dose primary series dose at 2, 4, and 6 months or school entry booster between 4 and 6 years of age.

Methods

This multicenter, observational, PMS study was conducted in real-world practice in South Korea for 6 years (2009–2015) in participants aged between 2 months and 6 years. The study outcomes included solicited reactions, unsolicited adverse events (AEs)/adverse drug reactions (ADRs), unexpected AEs/ADRs, and serious AEs (SAEs)/ADRs.

Results

Data from 647 participants was included in the safety analysis. Overall, 268 AEs were reported by 181 (28%) participants: 47 (17.5%) solicited reactions, 220 (82.1%) unsolicited AEs, and 1 (0.4%) unsolicited ADR. A total of 48 AEs (including 47 solicited reactions) were reported to have a causal relationship with the DTaP-IPV vaccine and were reported by 36 (5.6%) participants. A total of 212 unexpected AEs were reported by 152 (23.5%) participants, none of which had a causal relationship with the DTaP-IPV vaccine. Neither immediate AEs nor SAEs were reported during the study. Among the participants who reported AEs, 220 (34%) were on concomitant medications. Most AEs were of mild intensity, and all participants recovered.

Conclusion

No safety concerns related to the DTaP-IPV vaccine in a real-world setting were raised in participants aged 2–6 months for the primary series and 4–6 years for the school-entry booster dose in the Korean population. The DTaP-IPV vaccine was well tolerated and can be continued as part of routine immunization programs in infants and children.

Trial Registration: NCT01437423.

ERRATA CORRIGE

[This corrects the article on p. E530-E541 in vol. 61, PMID: 33628957.].

Waning Vaccine Immunity and Vaccination Responses in Children Treated for Acute Lymphoblastic Leukemia: A Canadian Immunization Research Network Study

BACKGROUND

There is no uniform guideline for postchemotherapy vaccination of children with acute lymphoblastic leukemia (ALL). We evaluated waning immunity to 14 pneumococcal serotypes, pertussis toxin (PT), tetanus toxoid (TT) and varicella, and immunogenicity of postchemotherapy diphtheria, tetanus, pertussis, hepatitis B, polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) and pneumococcal vaccination among previously vaccinated children treated for ALL.

METHODS

This was a multicenter trial of children with ALL enrolled 4-12 months postchemotherapy completion. Exclusion criteria included: infant ALL, relapsed ALL, and stem cell transplant recipients. Immunocompetent children were recruited as controls. Postchemotherapy participants received DTaP-IPV-Hib and 13-valent pneumococcal conjugate vaccine (PCV13) concurrently, followed by 23-valent pneumococcal polysaccharide vaccine (PPV23) 2 months later. Serology was measured at baseline, 2 and 12 months postvaccination. Adverse events were captured via surveys.

RESULTS

At enrollment, postchemotherapy participants (n = 74) were less likely than controls (n = 78) to be age-appropriately immunized with DTaP (41% vs 89%, P < .001) and PCV (59% vs 79%, P = .008). Geometric mean concentrations (GMCs) to TT, PT, PCV serotypes, and varicella were lower in postchemotherapy participants than controls after adjusting for previous vaccine doses (P < .001). Two months postvaccination, GMCs to TT, PT, and PCV serotypes increased from baseline (P < .001 for all antigens) and remained elevated at 12 months postvaccination. Antibody levels to PPV23 serotypes also increased postvaccination (P < .001). No serious adverse events were reported.

CONCLUSIONS

Children treated for ALL had lower antibody levels than controls against pneumococcal serotypes, tetanus, pertussis, and varicella despite previous vaccination. Postchemotherapy vaccination with DTaP-IPV-Hib, PCV13, and PPV23 was immunogenic and well tolerated. Children with ALL would benefit from systematic revaccination postchemotherapy.

CLINICAL TRIALS REGISTRATION

NCT02447718.

Common Genetic Variations Associated with the Persistence of Immunity following Childhood Immunization

Vaccines have revolutionized public health, preventing millions of deaths each year, particularly in childhood. Yet, there is considerable variability in the magnitude and persistence of vaccine-induced immunity. Maintenance of specific antibody is essential for continuity of vaccine-induced serological protection. We conducted a genome-wide association study into the persistence of immunity to three childhood vaccines: capsular group C meningococcal (MenC), Haemophilus influenzae type b, and tetanus toxoid (TT) vaccines. We detail associations between variants in a locus containing a family of signal-regulatory proteins and the persistence MenC immunity. We postulate a regulatory role for the lead SNP, with supporting epigenetic and expression quantitative trait loci data. Furthermore, we define associations between SNPs in the human leukocyte antigen (HLA) locus and the persistence of TT-specific immunity. Moreover, we describe four classical HLA alleles, HLA DRB1^∗0301, HLA DQB1^∗0201, HLA DQB1^∗0602, and HLA DRB1^∗1501, associated with TT-specific immunity, independent of the lead SNP association.

Use of tetanus-diphtheria (Td) vaccine in children 4-7 years of age: World Health Organization consultation of experts

For lifetime protection against diphtheria and tetanus, the World Health Organization (WHO) recommends six doses of diphtheria and tetanus containing vaccines. Td (reduced diphtheria toxoid, ≥2-5 IU) vaccines are currently licensed for ages 7 years and older, but use of Td vaccine for ages 4 years and older would have advantages for immunization programs in many low- and middle-income countries. For this reason, WHO convened an expert consultation to review the currently available evidence for the use of Td vaccine from 4 to 7 years of age which concluded: (1) no relevant biological difference in immune response in the relevant age group compared with children over 7 years of age; (2) adequate seroprotection in several studies with Td vaccine in the 4-7 age group and many studies using combination vaccines; (3) durable and protective response of at least 9-11 years duration in several longitudinal and modelling studies, (4) less reactogenicity compared with use of full-dose diphtheria vaccine, potentially improving the vaccination experience; and (5) adequate control of diphtheria in several countries using Td-containing combination vaccines in 4-7 year old children. On this basis, the experts concluded that from a programmatic perspective, Td vaccine given in ages 4-7 years, as a second booster dose in a six-dose series, would provide adequate protection against diphtheria and tetanus and recommended steps to include this change in age extension listed in the package insert.

Needle size for vaccination procedures in children and adolescents

BACKGROUND

This is an update of a Cochrane Review first published in 2015. The conclusions have not changed.Hypodermic needles of different sizes (gauges and lengths) can be used for vaccination procedures. The gauge (G) refers to the outside diameter of the needle tubing. The higher the gauge number, the smaller the diameter of the needle (e.g. a 23 G needle is 0.6 mm in diameter, whereas a 25 G needle is 0.5 mm in diameter). Many vaccines are recommended for injection into muscle (intramuscularly), although some are delivered subcutaneously (under the skin) and intradermally (into skin). Choosing an appropriate length and gauge of a needle may be important to ensure that a vaccine is delivered to the appropriate site and produces the maximum immune response while causing the least possible harm. Guidelines conflict regarding the sizes of needles that should be used for vaccinating children and adolescents.

OBJECTIVES

To assess the effects of using needles of different sizes for administering vaccines to children and adolescents on vaccine immunogenicity (the ability of the vaccine to elicit an immune response), procedural pain, and other reactogenicity events (adverse events following vaccine administration).

SEARCH METHODS

We updated our searches of CENTRAL, MEDLINE, Embase, and CINAHL to October 2017. We also searched proceedings of vaccine conferences and two trials registers.

SELECTION CRITERIA

Randomised controlled trials evaluating the effects of using hypodermic needles of any gauge or length to administer any type of vaccine to people aged from birth to 24 years.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted trial data and assessed the risk of bias. We contacted trial authors for additional information. We rated the quality of evidence using the GRADE system.

MAIN RESULTS

We included five trials involving 1350 participants in the original review. The updated review identified no new trials. The evidence from two small trials (one trial including infants and one including adolescents) was insufficient to allow any definitive statements to be made about the effects of the needles evaluated in the trials on vaccine immunogenicity and reactogenicity.The remaining three trials (1135 participants) contributed data to comparisons between 25 G 25 mm, 23 G 25 mm, and 25 G 16 mm needles. These trials included infants predominantly aged from two to six months undergoing intramuscular vaccination in the anterolateral thigh using the World Health Organization (WHO) injection technique (skin stretched flat, needle inserted at a 90° angle and up to the needle hub in healthy infants). The vaccines administered were combination vaccines containing diphtheria, tetanus, and whole-cell pertussis antigens (DTwP). In some trials, the vaccines also contained Haemophilus influenzae type b (DTwP-Hib) and hepatitis B (DTwP-Hib-Hep B) antigen components.Primary outcomesIncidence of vaccine-preventable diseases: No trials reported this outcome.Procedural pain and crying: Using a wider gauge 23 G 25 mm needle may slightly reduce procedural pain (low-quality evidence) and probably leads to a slight reduction in the duration of crying time immediately after vaccination (moderate-quality evidence) compared with a narrower gauge 25 G 25 mm needle (one trial, 320 participants). The effects are probably not large enough to be clinically relevant.Secondary outcomesImmune response: There is probably little or no difference in immune response, defined in terms of the proportion of seroprotected infants, between use of 25 G 25 mm, 23 G 25 mm, or 25 G 16 mm needles to administer a series of three doses of a DTwP-Hib vaccine at ages two, three, and four months (moderate-quality evidence, one trial, numbers of participants in analyses range from 309 to 402. The immune response to the pertussis antigen was not measured).Severe and non-severe local reactions: 25 mm needles (either 25 G or 23 G) probably lead to fewer severe and non-severe local reactions after DTwP-Hib vaccination compared with 25 G 16 mm needles (moderate-quality evidence, one trial, 447 to 458 participants in analyses). We estimate that one fewer infant will experience a severe local reaction (extensive redness and swelling) after the first vaccine dose for every 25 infants vaccinated with the longer rather than the shorter needle (number needed to treat for an additional beneficial outcome (NNTB) with a 25 G 25 mm needle: 25 (95% confidence interval (CI) 15 to 100); NNTB with a 23 G 25 mm needle: 25 (95% CI 17 to 100)). We estimate that one fewer infant will experience a non-severe local reaction (any redness, swelling, tenderness, or hardness (composite outcome)) at 24 hours after the first vaccine dose for every 5 or 6 infants vaccinated with a 25 mm rather than a 16 mm needle (NNTB with a 25 G 25 mm needle: 5 (95% CI 4 to 10); NNTB with a 23 G 25 mm needle: 6 (95% CI 4 to 13)). The results are similar after the second and third vaccine doses.Using a narrow gauge 25 G 25 mm needle may produce a small reduction in the incidence of local reactions after each dose of a DTwP vaccine compared with a wider gauge 23 G 25 mm needle, but the effect estimates are imprecise (low-quality evidence, two trials, 100 to 459 participants in analyses).Systemic reactions: The comparative effects of 23 G 25 mm, 25 G 25 mm, and 25 G 16 mm needles on the incidence of postvaccination fever and other systemic events such as drowsiness, loss of appetite, and vomiting are uncertain due to the very low quality of the evidence.

AUTHORS' CONCLUSIONS

Using 25 mm needles (either 23 G or 25 G) for intramuscular vaccination procedures in the anterolateral thigh of infants using the WHO injection technique probably reduces the occurrence of local reactions while achieving a comparable immune response to 25 G 16 mm needles. These findings are applicable to healthy infants aged two to six months receiving combination DTwP vaccines with a reactogenic whole-cell pertussis antigen component. These vaccines are predominantly used in low- and middle-income countries. The applicability of the findings to vaccines with acellular pertussis components and other vaccines with different reactogenicity profiles is uncertain.

Immunogenicity of a low-dose diphtheria, tetanus and acellular pertussis combination vaccine with either inactivated or oral polio vaccine compared to standard-dose diphtheria, tetanus, acellular pertussis when used as a pre-school booster in UK children: A 5-year follow-up of a randomised controlled study

This serological follow up study assessed the kinetics of antibody response in children who previously participated in a single centre, open-label, randomised controlled trial of low-dose compared to standard-dose diphtheria booster preschool vaccinations in the United Kingdom (UK). Children had previously been randomised to receive one of three combination vaccines: either a combined adsorbed tetanus, low-dose diphtheria, 5-component acellular pertussis and inactivated polio vaccine (IPV) (Tdap-IPV, Repevax(®); Sanofi Pasteur MSD); a combined adsorbed tetanus, low-dose diphtheria and 5-component acellular pertussis vaccine (Tdap, Covaxis(®); Sanofi Pasteur MSD) given concomitantly with oral polio vaccine (OPV); or a combined adsorbed standard-dose diphtheria, tetanus, 2-component acellular pertussis and IPV (DTap-IPV, Tetravac(®); Sanofi Pasteur MSD). Blood samples for the follow-up study were taken at 1, 3 and 5 years after participation in the original trial (median, 5.07 years of age at year 1), and antibody persistence to each vaccine antigen measured against defined serological thresholds of protection. All participants had evidence of immunity to diphtheria with antitoxin concentrations greater than 0.01IU/mL five years after booster vaccination and 75%, 67% and 79% of children who received Tdap-IPV, Tdap+OPV and DTap-IPV, respectively, had protective antitoxin levels greater than 0.1IU/mL. Long lasting protective immune responses to tetanus and polio antigens were also observed in all groups, though polio responses were lower in the sera of those who received OPV. Low-dose diphtheria vaccines provided comparable protection to the standard-dose vaccine and are suitable for use for pre-school booster vaccination.

Needle size for vaccination procedures in children and adolescents

BACKGROUND

Hypodermic needles of different sizes (gauges and lengths) can be used for vaccination procedures. The gauge (G) refers to the outside diameter of the needle tubing. The higher the gauge number, the smaller diameter of the needle (eg a 25 G needle is 0.5 mm in diameter and is narrower than a 23 G needle (0.6 mm)). Many vaccines are recommended for injection into muscle (intramuscularly), although some are delivered subcutaneously (under the skin) and intradermally (into skin). Choosing an appropriate length and gauge of a needle may be important to ensure that a vaccine is delivered to the appropriate site and produces the maximum immune response while causing the least possible harm. There are some conflicting guidelines regarding the lengths and gauges of needles that should be used for vaccination procedures in children and adolescents.

OBJECTIVES

To assess the effects of using needles of different lengths and gauges for administering vaccines to children and adolescents on vaccine immunogenicity (the ability of the vaccine to elicit an immune response), procedural pain, and other reactogenicity events (adverse events following vaccine administration).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library 2014, Issue 10), MEDLINE and MEDLINE in Progress via Ovid (1947 to November 2014), EMBASE via Ovid (1974 to November 2014), and CINAHL via EBSCOhost (1982 to November 2014). We also searched reference lists of articles and textbooks, the proceedings of vaccine conferences, and three clinical trial registers.

SELECTION CRITERIA

Randomised controlled trials evaluating the effects of using hypodermic needles of any gauge or length to administer any type of vaccine to people aged from birth to 24 years.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted trial data and assessed the risk of bias. We contacted trial authors for additional information. We rated the quality of evidence using the GRADE system.

MAIN RESULTS

We included five trials involving 1350 participants. Data for the primary review outcomes were either absent (for the incidence of vaccine-preventable diseases) or limited (for procedural pain and crying). The available evidence was compromised by the use of surrogate immunogenicity outcomes, incomplete blinding of outcome assessors, and imprecision for some outcomes. The evidence from two small trials was insufficient to allow any confident statements to be made about the effects of the needles evaluated in the trials on vaccine immunogenicity and reactogenicity.The remaining three trials (1135 participants) contributed data to comparisons between 25 G 25 mm, 23 G 25 mm, and 25 G 16 mm needles. These trials involved infants predominantly aged two to six months undergoing intramuscular vaccination in the anterolateral thigh using the World Health Organization (WHO) injection technique (skin stretched flat, needle inserted at a 90° angle and up to the needle hub in healthy infants). The vaccines administered were combination vaccines containing diphtheria, tetanus, and whole-cell pertussis antigens (DTwP). In some trials, the vaccines also contained Haemophilus influenzae type b (DTwP-Hib) and hepatitis B (DTwP-Hib-HepB) antigen components.We found moderate quality evidence from one trial that there is probably little or no difference in immune response, defined in terms of the proportion of seroprotected infants, between using 25 G 25 mm, 23 G 25 mm, or 25 G 16 mm needles to administer a series of three doses of a DTwP-Hib vaccine at ages two, three, and four months (numbers of participants in analyses range from 309 to 402. Immune response to pertussis antigen not measured).25 mm needles (either 23 G or 25 G) probably lead to fewer severe local reactions (extensive redness and swelling) and fewer non-severe local reactions (any redness, swelling, tenderness or hardness (composite outcome)) after DTwP-Hib vaccination compared with 25 G 16 mm needles. We estimate that one fewer infant will experience a severe local reaction after the first vaccine dose for every 25 infants vaccinated with the longer rather than the shorter needle (number needed to treat (NNT) 25 (95% confidence interval (CI) 15 to 100)). We estimate that one fewer infant will experience a non-severe local reaction at 24 hours after the first, second, and third vaccine doses for every five to eight infants vaccinated with the longer rather than the shorter needle (NNTs range from 5 (95% CI 4 to 10) to 8 (95% CI 5 to 34)) (moderate quality evidence, one trial for first and second doses, two trials for third dose, numbers of participants in analyses range from 413 to 528).Using a wider gauge needle (23 G 25 mm) may slightly reduce procedural pain (low quality evidence) and probably leads to a slight reduction in the duration of crying time immediately after vaccination (moderate quality evidence) compared with a narrower gauge (25 G 25 mm) needle (one trial, 320 participants). The effects are probably not large enough to be of any clinical relevance. The 25 G 25 mm needle may produce a small reduction in the incidence of local reactions after each dose of a DTwP vaccine compared with the 23 G 25 mm needle, but the effect estimates are imprecise (low quality evidence, two trials, numbers of participants in analyses range from 100 to 459).The comparative effects of 23 G 25 mm, 25 G 25 mm, and 25 G 16 mm needles on the incidence of post-vaccination fever, persistent inconsolable crying, and other systemic events such as drowsiness, loss of appetite, and vomiting are uncertain due to the very low quality of the evidence.

AUTHORS' CONCLUSIONS

Using 25 mm needles (either 23 G or 25 G) for intramuscular vaccination procedures in the anterolateral thigh of infants using the WHO injection technique probably reduces the occurrence of local reactions while achieving a comparable immune response to 25 G 16 mm needles. These findings are applicable to healthy infants aged two to six months receiving combination DTwP vaccines with a reactogenic whole-cell pertussis antigen component. These vaccines are predominantly used in developing countries. The applicability of the findings to vaccines with acellular pertussis components and other vaccines with different reactogenicity profiles is uncertain.

Two consecutive randomized controlled pertussis booster trials in children initially vaccinated in infancy with an acellular vaccine: The first with a five-component Tdap vaccine to 5-year olds and the second with five- or monocomponent Tdap vaccines at age 14-15 years

Prior study children from a DTaP efficacy trial were recruited at ages 5 and 15 years to randomized booster trials addressing immunogenicity and reactogenicity; 475 preschool children received mixed or separate injections of a reduced antigen vaccine (Tdap5, Sanofi Pasteur MSD) and an inactivated polio vaccine, and 230 adolescents received the same or another booster vaccine (Tdap1, SSI, Denmark). Pre-vaccination antibody concentrations against pertussis antigens were significantly higher at 15 than 5 years of age, probably due to natural boosting between the studies. Tdap5 induced comparable anti-PT concentrations at both ages, but antibody responses were significantly higher to filamentous haemagglutinin, pertactin and fimbriae 2/3 in adolescents. As expected, a higher amount of PT (Tdap1, 20μg) induced a stronger anti-PT response than a lower amount (Tdap5, 2.5μg). The frequency of adverse events was low and there were no serious adverse reactions. All local reactions had an early onset and a short duration. A large swelling or redness of more than half of the upper arm circumference was reported in 8/475 5-year-olds and in 6/230 15-year-olds. Children vaccinated with Tdap5 reported more moderate pain in adolescence than at preschool age, whereas itching was only reported in preschool children. Sweden introduced DTaP vaccines in 1996 after a 17-year hiatus with no general pertussis vaccination and pertussis was still endemic at the time of the studies. The frequency of adverse events was nevertheless low in both preschool children and adolescents and antibody responses were adequate. These studies document immunogenicity and reactogenicity in a trial cohort consecutively vaccinated with acellular pertussis vaccines from infancy to adolescence. The adolescent study was registered at ClinicalTrials.gov on 26 March 2009 (NCT00870350).

Should acellular pertussis vaccine be recommended to healthcare professionals?

The aim of this study was to describe recent changes in the epidemiology of pertussis and existing policies regarding recommended and mandatory occupational vaccinations for healthcare professionals (HCPs). The authors carried out an extensive review of references on the PubMed and SciELO databases and the official sites of the World Health Organization, Pan American Health Organization, Centers for Disease Control and Prevention, and Brazilian Ministry of Health, using the keywords pertussis, vaccines and healthcare professionals. Vaccination against pertussis is recommended for HCPs in the United States, Canada, nine European countries, Australia, Hong Kong, Singapore, Costa Rica, Argentina and Uruguay, and in some countries it is compulsory. In Brazil, only one publication discussing the risk of pertussis among HCPs was found. Considering the reemergence of pertussis and the great number of associated hospitalizations and deaths registered in 2011, it is necessary to review public policies regarding HCP pertussis vaccination, particularly among workers in frequent contact with young babies.

Maintenance of immune response throughout childhood following serogroup C meningococcal conjugate vaccination in early childhood

The objectives of this study were to evaluate the kinetics of antibody decline through childhood in a longitudinal study of a single cohort following serogroup C meningococcal (MenC) vaccine immunization in early childhood and to calculate the proportion of 11 to 13 year olds with protective levels of bactericidal antibody 10 years after immunization. United Kingdom children aged 11 to 13 years in 2010 who had previously taken part in a longitudinal study at the Oxford Vaccine Group had blood samples drawn between 2001 and 2010. Sera from each time point were analyzed for the MenC serum bactericidal antibody titer using a baby rabbit complement (rSBA) assay. The median age at MenC immunization was 21 months (range, 1 year 3 months to 3 years 9 months). The MenC rSBA geometric mean titer (GMT) at age 3.5 to 5 years was 8.0 (95% confidence interval, 6.5 to 9.9; n = 287). By age 11.5 to 13.5 years, the rSBA GMT had declined to 3.3 (2.5 to 4.4; n = 98). The percentage of children with rSBA titers of ≥1:8 (the threshold for protection) also declined from 38% (35% to 41%) to 15% (12% to 19%). We concluded that MenC rSBA titers wane rapidly following vaccination in early childhood and continue to decline into the second decade of life. Since nasopharyngeal colonization in adolescents probably provides the major reservoir for MenC in the population, declining immunity in this cohort is of concern. Sustaining high levels of antibody through booster vaccination in this cohort is likely necessary to avoid a resurgence of disease in the decade ahead.

Spotlight on Tdap₅ vaccine (Covaxis®) as a single-booster immunization for the prevention of tetanus, diphtheria, and pertussis: in children (aged ≥4 years), adolescents, and adults

Covaxis® (also licensed as Triaxis® or Adacel® in individual countries) is a Tdap₅ (i.e. combined tetanus toxoid, reduced diphtheria toxoid, five component acellular pertussis [namely detoxified pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae types 2 and 3]) vaccine for the prevention of diphtheria, tetanus, and pertussis. It is approved for use in Europe as a single intramuscular booster dose in children (aged ≥4 years), adolescents, and adults, and in the US it is approved for use in individuals aged 11-64 years. In large, randomized, controlled clinical trials conducted in the UK and North America, a single intramuscular booster dose of Covaxis® induced robust immune responses for all of its component antigens when given to children (aged ≥4 years), adolescents, and adults. In addition, Covaxis® vaccine was safe and generally well tolerated in terms of solicited and unsolicited local injection-site and systemic adverse events, most of which were of mild intensity and resolved without sequelae. Furthermore, the immunogenicity of each individual component and the reactogenicity of Covaxis® vaccine in children, adolescents, and adults was generally similar to that of comparator vaccines. Despite being a vaccine-preventable disease and having >90% primary vaccination coverage worldwide, pertussis remains uncontrolled, particularly amongst adolescents and adults. Given the changing epidemiology of pertussis and the requirement to reduce infection in adolescents and adults (including healthcare workers) and thereby prevent transmission of the disease from these individuals to very young infants, the new 'cocoon strategy' recommended in current vaccination guidelines has become a key strategy in the management of morbidity and mortality associated with pertussis. This strategy focuses on the immunization of healthcare workers, and the parents and family members of infants who are too young to have undergone primary immunization, so as to prevent the transmission of pertussis to these young at-risk infants. The implementation of the 'cocoon strategy' may finally give countries the ability to control pertussis infections in these at-risk infants and ultimately provide the desired herd immunity against pertussis. In line with this strategy, a booster dose of Covaxis® vaccine provides a valuable option to reduce pertussis morbidity and mortality, and to maintain seroprotection against diphtheria and tetanus in children (aged ≥4 years), adolescents, and adults.

Tdap5 vaccine (Covaxis): a review of its use as a single-booster immunization for the prevention of tetanus, diphtheria, and pertussis in children (aged 4 years), adolescents, and adults

Covaxis (also licensed as Triaxis or Adacel in individual countries) is a combined tetanus toxoid, reduced diphtheria toxoid, five component acellular pertussis (namely detoxified pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae types 2 and 3) vaccine for the prevention of diphtheria, tetanus, and pertussis. It is approved for use in Europe as a single intramuscular booster dose in children (aged ≥ 4 years), adolescents, and adults, and in the US it is approved for use in individuals aged 11-64 years. In large, randomized, controlled clinical trials conducted in the UK and North America, a single intramuscular booster dose of Covaxis induced robust immune responses for all of its component antigens when given to children (aged ≥ 4 years), adolescents, and adults. In addition, Covaxis vaccine was safe and generally well tolerated in terms of solicited and unsolicited local injection-site and systemic adverse events, most of which were of mild intensity and resolved without sequelae. Furthermore, the immunogenicity of each individual component and the reactogenicity of Covaxis vaccine in children, adolescents, and adults was generally similar to that of comparator vaccines. Despite being a vaccine-preventable disease and having >90% primary vaccination coverage worldwide, pertussis remains uncontrolled, particularly amongst adolescents and adults. Given the changing epidemiology of pertussis and the requirement to reduce infection in adolescents and adults (including healthcare workers) and thereby prevent transmission of the disease from these individuals to very young infants, the new 'cocoon strategy' recommended in current vaccination guidelines has become a key strategy in the management of morbidity and mortality associated with pertussis. This strategy focuses on the immunization of healthcare workers, and the parents and family members of infants who are too young to have undergone primary immunization, so as to prevent the transmission of pertussis to these young at-risk infants. The implementation of the 'cocoon strategy' may finally give countries the ability to control pertussis infections in these at-risk infants and ultimately provide the desired herd immunity against pertussis. In line with this strategy, a booster dose of Covaxis vaccine provides a valuable option to reduce pertussis morbidity and mortality, and to maintain seroprotection against diphtheria and tetanus in children (aged ≥ 4 years), adolescents, and adults.

Booster vaccination and 1-year follow-up of 4-8-year-old children with a reduced-antigen-content dTpa-IPV vaccine

Reduced-antigen-content pertussis vaccines designed initially for booster vaccination of adolescents and adults can also be used to vaccinate pre-school age children. Combination vaccines, which reduce the number of administered injections, combine multiple antigens including inactivated poliovirus (IPV), which is recommended in this age group in some countries. This randomised, controlled study compared a combined diphtheria-tetanus-acellular pertussis-inactivated polio-containing booster vaccine, dTpa-IPV (Boostrix Polio, n=822), to separately administered dTpa (Boostrix) and IPV (IPV Mérieux, n=136) in 4-8-year-old children who had previously received four doses of DTPa. Additional serological assessment was performed 1 year after the booster dose. One month after vaccination, seroprotection/vaccine response rates were similar for both groups. At least 99.9% of the subjects had protective antibodies against diphtheria, tetanus and polio, and at least 90.1% had a vaccine response to pertussis antigens after dTpa-IPV. Reactogenicity of dTpa-IPV was comparable to dTpa + IPV. Fever and grade 3 loss of appetite occurred more commonly after dTpa-IPV, whereas swelling and grade 3 pain occurred more frequently after separately administered dTpa + IPV (P<0.05 for all). However, 95% CIs overlapped in all cases. Large swelling reactions after dTpa-IPV occurred less commonly than have been reported after a fifth dose of DTPa. One year after the booster, 98.6% of the subjects tested continued to have protective antibodies against diphtheria, tetanus and polio, and at least 81.2% were seropositive for pertussis components. The reduced-antigen-content dTpa-IPV vaccine was immunogenic, well tolerated and safe in pre-school age children. It provides immunity against four diseases in a single injection, with the potential reactogenicity benefit of a reduced-antigen dose.

Childhood immunisation: what is the future?

Improved immunisation programmes and the development of new vaccines provide unprecedented opportunities to improve and sustain the health of our children. There are major challenges ahead in communicating the benefits of immunisation to all populations and in delivering vaccines to those in greatest need. In this review on immunisation, I have asked international opinion leaders to comment on the present and the future of immunisation to provide signposts for the narrative.

Evaluation of a diphtheria-tetanus-acellular pertussis-inactivated poliovirus-Haemophilus influenzae type b vaccine given concurrently with meningococcal group C conjugate vaccine at 2, 3 and 4 months of age

BACKGROUND AND OBJECTIVE

In view of the possible introduction of diphtheria-tetanus-acellular pertussis-inactivated poliovirus-Haemophilus influenzae type b (DTaP-IPV-Hib, eg Pediacel) vaccine in the UK, a study of the immunogenicity of Pediacel when given with one of two different meningococcal group C conjugate (MCC) vaccines at 2, 3 and 4 months of age was conducted.

METHODS

Randomised controlled study in 241 infants.

RESULTS

Post vaccination, the proportion of infants with anti-polyribosylribitol phosphate (PRP) levels > or =0.15 microg/ml was 93.2% (95% confidence interval (CI) 86.6 to 96.7) in the Pediacel group compared with 100% (95% CI 96.4 to 100) in the diphtheria-tetanus-whole-cell pertussis-Haemophilus influenzae type b (DTwP-Hib) group. The anti-PRP response was lower in infants receiving either Pediacel or DTwP-Hib when these vaccines were given concomitantly with meningococcal group C conjugate with diphtheria-derived protein CRM(197) as conjugate protein (MCC-CRM) compared with meningococcal group C conjugate with tetanus toxoid as conjugate protein (MCC-TT). For group C meningococcus, the proportion of infants with serum bactericidal antibody (SBA) titre > or =1:8 in the Pediacel group was 99.0% compared with 100% in the DTwP-Hib group. The MCC SBA geometric mean titre (GMT) was lower in those receiving Pediacel with MCC-TT than in those receiving DTwP-Hib with MCC-TT, although all titres were well above the protective threshold. The MCC SBA GMT was similar in those receiving Pediacel and DTwP-Hib and MCC-CRM. Responses to all other vaccine components were equivalent in the two groups.

CONCLUSIONS

Pediacel is immunogenic when given at 2, 3 and 4 months of age. Coadministration of MCC vaccine can influence the Hib response, and the MCC response to a tetanus conjugate can be influenced by the nature of the coadministered DTP-Hib vaccine.

An adolescent and adult formulation combined tetanus, diphtheria and five-component pertussis vaccine

Pertussis causes substantial morbidity among adolescents and adults, as well as other persons in contact with affected individuals. In the context of widespread childhood immunization, vaccination of adolescents and adults is a relatively new strategy for reducing the disease in all age groups. ADACEL is a tetanus-diphtheria-acellular pertussis combination vaccine (incorporating pertussis toxoid, filamentous hemagglutinin, pertactin and fimbriae type 2 and 3 antigens) formulated for use in adolescents and adults based on similar products designed for infants and children. ADACEL vaccine is approved for use in Australia, Canada, Germany and the USA, and has been demonstrated to induce robust immune responses and acceptable levels of reactogenicity in clinical trials. Surveillance data from Canada, where ADACEL vaccine has been used in adolescents and adults in conjunction with ongoing childhood vaccination for several years, indicate an enhanced overall reduction in pertussis disease.

A comparison of booster immunisation with a combination DTPa-IPV vaccine or DTPa plus IPV in separate injections when co-administered with MMR, at age 4–6 years

This study evaluated GSK's combined DTPa-IPV vaccine (Infanrix-IPV) given as a fifth consecutive acellular pertussis booster dose in conjunction with the second dose of MMR vaccine (Priorix) in children aged 4-6 years. The immunogenicity and reactogenicity of this vaccine regimen was compared with separate injections of DTPa and IPV when given concomitantly with MMR. A cohort of 362 children previously primed with four doses of DTPa and OPV, and a single dose of MMR were randomized to receive either DTPa-IPV+MMR (N=181) or DTPa+IPV+MMR (N=181). Antibody concentrations were measured prior to and 1 month after the booster dose. After immunisation all subjects from both groups had seroprotective antibody levels against diphtheria, tetanus and the three poliovirus serotypes, > or = 96% showed vaccine response to PT, FHA and PRN, all were seropositive to mumps and rubella, and all but one subject were seropositive to measles. Immunogenicity results for each component antigen were similar for DTPa-IPV and separately co-administered DTPa and IPV. Local reactions were common with 24.0% and 31.1% of children experiencing swelling >50mm at the DTPa-IPV and DTPa injection sites, respectively. The DTPa-IPV combination did not increase the incidence or intensity of adverse events compared with separately administered DTPa+IPV. The response to the concomitantly administered MMR vaccine was similar in the two groups and similar to previously reported responses for a second dose of MMR. This combined DTPa-IPV vaccine has a similar reactogenicity profile to DTPa, is immunogenic when given as a booster dose at 4-6 years of age, and has no impact on the immunogenicity of a co-administered second dose of MMR vaccine.

Prevention of pertussis across the age spectrum through the use of the combination vaccines PENTACEL™ and ADACEL™

Acellular pertussis-containing combination vaccines are widely used in the developed world for the control of pertussis and have been successful in controlling disease in preschool-aged children. Combination vaccines formulated for use in adolescents and adults have been developed more recently and are increasingly being implemented for the control of pertussis in these age groups. One such family of products is PENTACEL (Haemophilus influenzae type b conjugate vaccine reconstituted with component pertussis vaccine and diphtheria and tetanus toxoids adsorbed combined with inactivated poliomyelitis vaccine, DTaP-IPV-Hib), for use in young children, and ADACEL (tetanus and diphtheria toxoids adsorbed combined with component pertussis vaccine, dTap) for use in adolescents and adults. These products have been demonstrated to be safe, immunogenic and effective for the control of pertussis and the other included diseases.

Safety and immunogenicity of a combined DTPa–IPV vaccine administered as a booster from 4 years of age: A review

A combined DTPa-IPV booster vaccine was administered as a 4th or 5th dose after DTPa or DTPw priming. Over 99% vaccines developed antibody levels considered to be protective to diphtheria, tetanus and poliovirus, and >95% mounted a response to acellular pertussis antigens. Rectal temperature >39.5 degrees C was observed in at most 3.2% of vaccinees. Swelling >50 mm occurred in 24% of DTPa-primed compared to 5.5% of DTPw-primed children. Large swelling involving the entire upper arm (extending to involve the elbow joint) was reported for up to 1.2% of DTPa-primed subjects, which is consistent with literature reports for other DTPa vaccines.