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

Review of scientific evidence to support recommendations of the full-dose DTaP-IPV vaccination in pre-school age children in Italy

INTRODUCTION

Two vaccine formulations are available to prevent diphtheria, tetanus, pertussis, and poliomyelitis: the pediatric full-dose (DTaP-IPV) and the reduced dose formulation (dTap-IPV). Different immunization schedules are internationally recommended for the pre-school booster dose.

AREAS COVERED

International and Italian recommendations, scientific evidence on immunogenicity and safety of DTaP/dTap vaccines to support the full dose as a pre-school booster and Italian vaccination coverage (VC) up to adolescence.

EXPERT OPINION

The WHO recommends a '3+1' schedule with DTaP vaccine for primary immunization, followed by a pre-school booster with DTaP or dTap vaccine. In Italy, a '2+1' schedule, with no booster in the second year, and a pre-school booster dose are recommended with DTPa-IPV vaccines. Studies showed a non-inferior immunogenicity in dTap vaccinees in pre-school age; nevertheless, the antibody titers were usually greater in children vaccinated with DTaP, while lower frequencies of adverse events were recorded in children receiving dTap. Italian VCs for pre-school and adolescent boosters have not been satisfactory, which further reduced during the COVID-19 period. In Italy, the pre-school booster offers the last chance to receive a full dose of DTaP vaccine, thus, representing the most suitable intervention to provide lasting protection in children.

Indian Academy of Pediatrics (IAP) Advisory Committee on Vaccines and Immunization Practices (ACVIP): Recommended Immunization Schedule (2020-21) and Update on Immunization for Children Aged 0 Through 18 Years

Justification

In view of new developments in vaccinology and the availability of new vaccines, there is a need to revise/review the existing immunization recommendations.

Process

Advisory Committee on Vaccines and Immunization Practices (ACVIP) of Indian Academy of Pediatrics (IAP) had a physical meeting in March, 2020 followed by online meetings (September-October, 2020), to discuss the updates and new recommendations. Opinion of each member was sought on the various recommendations and updates, following which an evidence-based consensus was reached.

Objectives

To review and revise the IAP recommendations for 2020–21 and issue recommendations on existing and new vaccines.

Recommendations

The major changes include recommendation of a booster dose of injectable polio vaccine (IPV) at 4–6 years for children who have received the initial IPV doses as per the ACVIP/IAP schedule, re-emphasis on the importance of IPV in the primary immunization schedule, preferred timing of second dose of varicella vaccine at 3–6 months after the first dose, and uniform dosing recommendation of 0.5 mL (15 µg HA) for inactivated influenza vaccines.

Indian Academy of Pediatrics (IAP) Advisory Committee on Vaccines and Immunization Practices (ACVIP): Recommended Immunization Schedule (2020-21) and Update on Immunization for Children Aged 0 Through 18 Years

JUSTIFICATION

In view of new developments in vaccinology and the availability of new vaccines, there is a need to revise/review the existing immunization recommendations.

PROCESS

Advisory Committee on Vaccines and Immunization Practices (ACVIP) of Indian Academy of Pediatrics (IAP) had a physical meeting in March, 2020 followed by online meetings (September-October, 2020), to discuss the updates and new recommendations. Opinion of each member was sought on the various recommendations and updates, following which an evidence-based consensus was reached.

OBJECTIVES

To review and revise the IAP recommendations for 2020-21 and issue recommendations on existing and new vaccines.

RECOMMENDATIONS

The major changes include recommendation of a booster dose of injectable polio vaccine (IPV) at 4-6 years for children who have received the initial IPV doses as per the ACVIP/IAP schedule, re-emphasis on the importance of IPV in the primary immunization schedule, preferred timing of second dose of varicella vaccine at 3-6 months after the first dose, and uniform dosing recommendation of 0.5 mL (15 µg HA) for inactivated influenza vaccines.

Post-marketing surveillance to assess the safety and tolerability of a combined diphtheria, tetanus, acellular pertussis and inactivated poliovirus vaccine (DTaP-IPV) in Korean children

Infanrix-IPV (GSK, Belgium) is a diphtheria, tetanus, acellular pertussis, and inactivated poliovirus combination vaccine (DTaP-IPV) licensed in many countries including Korea. In accordance with Korean regulations, we conducted a post-marketing surveillance (PMS) to evaluate the safety of DTaP-IPV administered to Korean children in routine immunization schedules. Children aged <7 years receiving at least one dose of DTaP-IPV either as part of a primary (3-dose) vaccination series or as a subsequent booster were enrolled. Adverse events (AEs), adverse drug reactions (ADRs) and serious AEs (SAEs) were recorded after each dose during the 30-day post-vaccination follow-up period. Among a total of 639 children, 289 subjects (45.2%) experienced AEs, mostly (79.2%) assessed as being unlikely to be related to the vaccination. ADRs were reported in 13.0% of subjects. Fever was the most commonly reported expected AE (11.9% of subjects) and also the most commonly reported expected ADR (8.5% of subjects). No obvious association between AE incidence and vaccine dose sequence was apparent. An unexpected AE was seen in 32.9% of children, and unexpected ADRs were far less common (1.9%). Thirty-four SAEs were recorded in 26 subjects (4.1%), in two of whom a causal association with the vaccine could not be excluded, although both resolved quickly. Data from this PMS indicate that DTaP-IPV has an acceptable safety profile when given to Korean children in accordance with local prescribing recommendations in routine childhood immunization. ClinicalTrials.gov identifier: NCT01568060

Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole-cell pertussis (wP) vaccines was suspended in some countries in the 1970s and 1980s because of concerns about adverse effects. Following this action, there was a resurgence of whooping cough. Acellular pertussis (aP) vaccines, containing purified or recombinant Bordetella pertussis (B. pertussis) antigens, were developed in the hope that they would be as effective, but less reactogenic than the whole-cell vaccines. This is an update of a Cochrane review first published in 1999, and previously updated in 2012. In this update, we included no new studies.

OBJECTIVES

To assess the efficacy and safety of acellular pertussis vaccines in children and to compare them with the whole-cell vaccines.

SEARCH METHODS

We searched CENTRAL (2013, Issue 12), MEDLINE (1950 to January week 2, 2014), EMBASE (1974 to January 2014), Biosis Previews (2009 to January 2014) and CINAHL (2009 to January 2014).

SELECTION CRITERIA

We selected double-blind randomised efficacy and safety trials of aP vaccines in children up to six years old, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias in the studies. Differences in trial design precluded a meta-analysis of the efficacy data. We pooled the safety data from individual trials using a random-effects meta-analysis model.

MAIN RESULTS

We included six efficacy trials with a total of 46,283 participants and 52 safety trials with a total of 136,541 participants. Most of the safety trials did not report the methods for random sequence generation, allocation concealment and blinding, which made it difficult to assess the risk of bias in the studies. The efficacy of multi-component (≥ three) vaccines varied from 84% to 85% in preventing typical whooping cough (characterised by 21 or more consecutive days of paroxysmal cough with confirmation of B. pertussis infection by culture, appropriate serology or contact with a household member who has culture-confirmed pertussis), and from 71% to 78% in preventing mild pertussis disease (characterised by seven or more consecutive days of cough with confirmation of B. pertussis infection by culture or appropriate serology). In contrast, the efficacy of one- and two-component vaccines varied from 59% to 78% against typical whooping cough and from 41% to 58% against mild pertussis disease. Multi-component acellular vaccines are more effective than low-efficacy whole-cell vaccines, but may be less effective than the highest-efficacy whole-cell vaccines. Most systemic and local adverse events were significantly less common with aP vaccines than with wP vaccines for the primary series as well as for the booster dose.

AUTHORS' CONCLUSIONS

Multi-component (≥ three) aP vaccines are effective in preventing whooping cough in children. Multi-component aP vaccines have higher efficacy than low-efficacy wP vaccines, but they may be less efficacious than the highest-efficacy wP vaccines. Acellular vaccines have fewer adverse effects than whole-cell vaccines for the primary series as well as for booster doses.

Booster vaccination: the role of reduced antigen content vaccines as a preschool booster

The need for boosters for tetanus, diphtheria, pertussis, and polio, starting from preschool age, is related to the waning immune protection conferred by vaccination, the elimination/reduction of natural boosters due to large-scale immunization programs, and the possibility of reintroduction of wild agents from endemic areas. Taking into account the relevance of safety/tolerability in the compliance with vaccination among the population, it have been assessed whether today enough scientific evidences are available to support the use of dTap-IPV booster in preschool age. The review of the literature was conducted using the PubMed search engine. A total of 41 works has been selected; besides, the documentation produced by the World Health Organization, the European Centre for Disease Control, and the Italian Ministry of Health has been consulted. Many recent papers confirm the opportunity to use a low antigenic dose vaccine starting from 4 to 6 years of age. There is also evidence that 10 years after immunization the rate of seroprotected subjects against diphtheria does not differ significantly between those vaccinated with paediatric dose (DTaP) or reduced dose (dTaP or dTap) product. The dTpa vaccine is highly immunogenic for diphtheria toxoids regardless of prior vaccination history (2 + 1 and 3 + 1 schedules).

Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole-cell pertussis (wP) vaccines was suspended in some countries in the 1970s and 1980s because of concerns about adverse effects. Following such action, there was a resurgence of whooping cough. Acellular pertussis (aP) vaccines, containing purified or recombinant Bordetella pertussis (B. pertussis) antigens, were developed in the hope that they would be as effective, but less reactogenic than the whole-cell vaccines.

OBJECTIVES

To assess the efficacy and safety of acellular pertussis vaccines in children.

SEARCH METHODS

We searched the Cochrane Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 4) which contains the Cochrane Acute Respiratory Infections Group's Specialised Register, MEDLINE (1950 to December week 4, 2011), EMBASE (1974 to January 2012), Biosis Previews (2009 to January 2012), and CINAHL (2009 to January 2012).

SELECTION CRITERIA

We selected double-blind randomised efficacy and safety trials of aP vaccines in children up to six years old, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias in the studies. Differences in trial design precluded a meta-analysis of the efficacy data. We pooled the safety data from individual trials using a random-effects meta-analysis model.

MAIN RESULTS

We included six efficacy trials with a total of 46,283 participants and 52 safety trials with a total of 136,541 participants. Most of the safety trials did not report the methods for random sequence generation, allocation concealment and blinding, which made it difficult to assess the risk of bias in the studies. The efficacy of multi-component (≥ three) vaccines varied from 84% to 85% in preventing typical whooping cough (characterised by 21 or more consecutive days of paroxysmal cough with confirmation of B. pertussis infection by culture, appropriate serology or contact with a household member who has culture-confirmed pertussis), and from 71% to 78% in preventing mild pertussis disease (characterised by seven or more consecutive days of cough with confirmation of B. pertussis infection by culture or appropriate serology). In contrast, the efficacy of one- and two-component vaccines varied from 59% to 75% against typical whooping cough and from 13% to 54% against mild pertussis disease. Multi-component acellular vaccines are more effective than low-efficacy whole-cell vaccines, but may be less effective than the highest-efficacy whole-cell vaccines. Most systemic and local adverse events were significantly less common with aP vaccines than with wP vaccines for the primary series as well as for the booster dose.

AUTHORS' CONCLUSIONS

Multi-component (≥ three) aP vaccines are effective and show less adverse effects than wP vaccines for the primary series as well as for booster doses.

Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole-cell pertussis vaccines was suspended in some countries in the 1970s/1980s because of concerns about adverse effects. There was a resurgence of whooping cough. Acellular pertussis vaccines (containing purified or recombinant Bordetella pertussis antigens) were developed in the hope that they would be as effective but less reactogenic than the whole-cell vaccines.

OBJECTIVES

To assess the efficacy and safety of acellular pertussis vaccines in children.

SEARCH STRATEGY

We searched the Cochrane Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 2) which contains the Acute Respiratory Infections Group's Specialised Register; MEDLINE (1950 to April week 2 2009) and EMBASE (1974 to April 2009).

SELECTION CRITERIA

Double-blind randomised efficacy and safety trials of acellular pertussis vaccines in children up to six years old, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed data extraction and study quality assessment. Differences in trial design precluded pooling of the efficacy data. The safety data from individual trials were pooled using the Cochrane statistical package Review Manager 5.

MAIN RESULTS

Six efficacy trials and 52 safety trials were included. The efficacy of multi-component (≥ 3) vaccines varied from 84% to 85% in preventing typical whooping cough, and from 71% to 78% in preventing mild pertussis disease. In contrast, the efficacy of one- and two-component vaccines varied from 59% to 75% against typical whooping cough, and from 13% to 54% against mild pertussis disease. Multi-component acellular vaccines is more effective than low-efficacy whole-cell vaccines, but may be less effective than the highest-efficacy whole-cell vaccines. Most systemic and local adverse events were significantly less common with acellular than with whole-cell pertussis vaccines for the primary series as well as for the booster dose.

AUTHORS' CONCLUSIONS

Multi-component acellular pertussis vaccines are effective, and show less adverse effects than whole-cell pertussis vaccines for the primary series as well as for booster doses.

Graphic-output temperature data loggers for monitoring vaccine refrigeration: implications for pertussis

We conducted the first US study using graphic-output temperature data loggers in quantifying cold chain failure. Fifty-four vaccine refrigerators of a county outpatient health system were studied. Forty-eight percent maintained temperatures of 2°C to 8°C and 24% had protracted periods of temperatures less than 0°C. The correlation between the percentage of refrigerators with freezing temperatures and the pertussis rate for each health region was r = 0.76. The findings suggest that improper vaccine storage may have contributed to recent increases in pertussis rates.

New Combination Vaccines: DTaP-IPV (Kinrix) and DTaP-IPV/Hib (Pentacel)

Objective:

To evaluate the clinical utility of diphtheria and tetanus toxoids and acellular pertussis adsorbed and inactivated poliovirus vaccine ([DTaP-IPV]; Kinrix) and diphtheria and tetanus toxoids and acellular pertussis adsorbed, Inactivated poliovirus and Haemophilus b conjugate (tetanus toxoid conjugate) vaccine ([DTaP-IPV/Hib]; Pentacel) in the schedule for pediatric immunizations.

Data Sources:

PubMed was searched (1966–April 2009) using the key words Kinrix and Pentacel. Subject headings included vaccines, combined; diphtheria-tetanus-pertussis vaccine; diphtheria-tetanus-acellular pertussis vaccines; poliovirus vaccine, inactivated; and Haemophilus influenzae type b polysaccharide vaccinetetanus toxin conjugate. The search was limited to English-language publications involving humans. Product labeling was obtained from GlaxoSmithKline and Sanofi Pasteur. The Centers for Disease Control and Prevention (CDC) Web site was searched for relevant recommendations published June 2008–October 2009.

Study Selection And Data Extraction:

Phase 2 and 3 clinical trials evaluating immunogenicity and safety of DTaP-IPV and DTaP-IPV/Hib were reviewed. Published trials were supplemented with abstracts, review articles, manufacturer product labeling, and CDC recommendations.

Data Synthesis:

DTaP-IPV is immunogenic compared to its component vaccines, with no effect of concomitantly administered measles, mumps, and rubella vaccine. Although injection site pain has occurred more with the combination vaccine, its use would reduce by 1 the number of injections given when a child is 4–6 years old. DTaP-IPV/Hib is immunogenic and safe compared to separate vaccines. Immunogenicity to 7-valent pneumococcal conjugate vaccine and hepatitis B (HepB) vaccine is not affected by concomitant administration. DTaP-IPV/Hib decreases injections by up to 7 when given at 2, 4, 6, and 15–18 months of age. It fits into the schedule more easily than DTaP-HepB-IPV (Pediarix), the other DTaP-containing combination vaccine indicated for the primary infant series.

Conclusions:

DTaP-IPV and DTaP-IPV/Hib combination vaccines are immunogenic and safe when given to infants and children. They reduce the number of required injections. Combination vaccines are encouraged to promote timely vaccination and complete immunization schedules.

Cellular immunity as a potential cause of local reactions to booster vaccination with diphtheria and tetanus toxoids and acellular pertussis antigens

BACKGROUND

Booster doses of diphtheria-tetanus-acellular pertussis (DTaP) vaccines restore waning serum antibody values but frequently cause local inflammation. Cell-mediated immunity (CMI) develops after primary DTaP vaccination and might contribute to local reactions to booster doses, a possibility explored in this study.

METHODS

Healthy 4 to 5-year-old children were bled before DTaP.IPV booster vaccination. Peripheral blood mononuclear cells were tested for proliferative responses to D toxoid (DT), T toxoid, pertussis toxoid, pertactin, filamentous hemagglutinin and fimbriae (FIM) types 2, 3, and cytokine release patterns assessed. Proliferative responses were examined in relation to prebooster serum antibody concentrations and local reaction rates, previously reported.

RESULTS

Among 167 subjects tested, proliferative response rates were: filamentous hemagglutinin 95%, pertussis toxoid 90%, T toxoid 84%, pertactin 67%, DT 41%, and FIM 31%. Responses were present to 3 to 6 antigens in 87% of subjects and absent altogether in 2%. Subjects without residual pertussis antibodies often had CMI to pertussis antigens. Subjects with CMI had higher corresponding serum antibody concentrations before the booster, compared with CMI-negative subjects. CMI responses were mixed TH1/TH2 type by cytokine profile for all antigens. Injection site erythema (>or=5 mm) was twice as frequent in those with than without CMI to DT (P=0.009) or FIM (P=0.042, Fisher exact test), the only antigens evaluable.

CONCLUSION

CMI to vaccine antigens was often detectable in children before preschool booster vaccination and preliminary evidence suggests a role for CMI in local reactions to this dose.

Kinrix: a new combination DTaP-IPV vaccine for children aged 4-6 years

Combination vaccines allow the administration of multiple vaccine antigens without the need for multiple injections. Recently, a combined diphtheria toxoid, tetanus toxoid, acellular pertussis and inactivated poliomyelitis vaccine (DTaP-IPV), Kinrix, has been licensed in the USA for use as the fifth DTaP dose and fourth IPV dose in children 4-6 years of age. Clinical trials have shown Kinrix to be immunogenic in 4-6-year-old children, with a safety profile comparable with that of separate DTaP and IPV vaccination. The use of Kinrix reduces by one the number of injections required to provide this age group with all recommended immunizations. Strategies such as the use of combined vaccines can help to maintain high levels of coverage against diphtheria, tetanus, pertussis and poliomyelitis diseases.

WITHDRAWN: Acellular vaccines for preventing whooping cough in children

BACKGROUND

Routine use of whole cell pertussis vaccines was suspended in some countries in the late 1970s and early 1980s, leading to a resurgence of whooping cough. Acellular pertussis vaccines containing purified or recombinant Bordetella pertussis antigens were developed in the hope that they would be as effective but less toxic than the whole cell vaccines.

OBJECTIVES

The objective of this review was to assess the effects of acellular pertussis vaccines in children.

SEARCH STRATEGY

The Cochrane Controlled Trials Register and Medline were searched up to January 1998.

SELECTION CRITERIA

Double-blind randomised efficacy and safety trials of acellular pertussis vaccines in children, with active follow-up of participants and laboratory verification of pertussis cases.

DATA COLLECTION AND ANALYSIS

One reviewer assessed trial quality and extracted data.

MAIN RESULTS

Six efficacy trials and 45 safety trials were included. Acellular pertussis vaccines with three or more pertussis vaccines were more effective than those with one or two antigens. They were also more effective than one type of whole cell pertussis vaccine, but less effective than two other types of whole cell vaccines. Differences in trial design precluded pooling of the efficacy data and results should be interpreted with caution. Most systemic and local adverse events were significantly less common with acellular than with whole cell pertussis vaccines.

AUTHORS' CONCLUSIONS

Multi-component acellular pertussis vaccines are effective, and show less adverse effects than whole cell pertussis vaccines. However in areas where whooping cough is more likely to be fatal, the higher toxicity of some whole cell vaccines may be offset by their increased effectiveness.

Diphtheria-tetanus-acellular pertussis and inactivated poliovirus vaccines given separately or combined for booster dosing at 4-6 years of age

BACKGROUND

In the United States, diphtheria-tetanus-acellular pertussis (DTaP) and inactivated poliovirus (IPV) booster vaccinations are recommended for children 4-6 years of age. A combined DTaP-IPV vaccine is being developed, which would reduce by one the number of injections in this age group.

METHODS

Children 4-6 years of age were randomized (1:1:1:1) to receive booster vaccination with 1 of 3 combined DTaP-IPV lots plus the measles, mumps, and rubella vaccine (N = 3156 for pooled lots) or separate doses of DTaP + IPV + measles, mumps, and rubella vaccine (N = 1053). Immunogenicity was assessed in a subset of children (N = 1331). Safety (solicited and unsolicited symptoms) including detailed assessment of local swelling reactions, was assessed in all children.

RESULTS

Increases in antibody geometric mean concentrations/titers 1 month after vaccination were observed for the diphtheria, tetanus, acellular pertussis, and polio antigens. At least 92.2% of combined DTaP-IPV subjects and 92.6% of separate DTaP + IPV subjects had a postvaccination booster response for one or more DTaP antigens. Booster responses to one or more poliovirus antigens were observed in at least 96.6% of combined DTaP-IPV subjects and 92.8% of separate DTaP + IPV subjects. The combined DTaP-IPV vaccine was noninferior to separately administered DTaP and IPV vaccines with respect to DTaP antigen booster response rates and poliovirus antibody geometric mean titers ratios. Reporting of solicited local and systemic events was comparable between both groups.

CONCLUSIONS

The combination DTaP-IPV vaccine provided immunogenicity and reactogenicity that is comparable to separately administered DTaP and IPV vaccines, with the advantage of requiring one less injection.

Adverse events following booster doses of diphtheria-tetanus-inactivated poliovirus and acellular pertussis vaccines for 4-year-old children in The Netherlands

The aim of the study was to assess the incidence and severity of local reactions and systemic events among 4-year-old children receiving a fifth dose of diphtheria-tetanus-inactivated poliovirus (dT-IPV) and acellular pertussis (aP) vaccines. Of 810 children, 483 had no adverse events following immunization. Of the reported local reactions of 281 children, pain was the most frequent (n=246). Eighty-one children developed redness, and 54, swelling. Pain, reduced use of the arm, redness, and swelling occurred significantly more often at the dT-IPV injection site than at the aP injection site (p<0.05). Local reactions were mainly mild and transient. Among the 104 reported systemic events, fever was the most frequent (n=42). In general, the vaccinations for the 4-year-olds are well tolerated.

Booster immunization with a hexavalent diphtheria, tetanus, acellular pertussis, hepatitis B, inactivated poliovirus vaccine and Haemophilus influenzae type b conjugate combination vaccine in the second year of life: safety, immunogenicity and persistence of antibody responses

The immunogenicity and reactogenicity of booster vaccination with GSK Biologicals' hexavalent DTPa-HBV-IPV/Hib vaccine was assessed in toddlers aged 12-18 months previously primed with the same combination (N=341), or with DTPa-IPV/Hib and HBV administered separately (N=102; Trials 217744/059 and 217744/096). Antibody persistence at age 4-6 years was also assessed in children who had received a 4th consecutive dose of DTPa-HBV-IPV/Hib vaccine or separate DTPa-IPV/Hib and HBV vaccines in this study and in another study conducted under similar conditions in Germany. Prior to booster vaccination in the second year of life, antibody concentrations and seroprotection rates were similar irrespective of the primary vaccine used. One month after boosting with DTPa-HBV-IPV/Hib, substantial antibody increases were observed against all vaccine antigens indicative of previous immune priming. Seropositivity and booster response rates against all antigens were 97.4-100%. Reactogenicity following booster vaccination with DTPa-HBV-IPV/Hib was similar regardless of the primary regimen used. Three to four years after administration of the 4th DTPa-HBV-IPV/Hib dose, >90% vaccinees had persistent protective antibody concentrations against diphtheria, hepatitis B, Hib and the three poliovirus types. Anti-tetanus antibody concentrations were > or = 0.1 IU/ml in 76.4% subjects and seropositivity for pertussis antibodies ranged from 34.5% for PT to 98.9% for FHA. In conclusion, the combined hexavalent DTPa-HBV-IPV/Hib vaccine is immunogenic and safe when used for boosting in the second year of life, regardless of the primary vaccine used, and offers sustained protection during early childhood and beyond.

Ultrasound examination of extensive limb swelling reactions after diphtheria-tetanus-acellular pertussis or reduced-antigen content diphtheria-tetanus-acellular pertussis immunization in preschool-aged children

OBJECTIVE

The aim of this study was to determine the site, extent, and resolution of tissue involvement when extensive limb swelling occurred in the injected limb for children who received diphtheria-tetanus-acellular pertussis or reduced-antigen content diphtheria-tetanus-acellular pertussis vaccine at 4 to 6 years of age.

METHODS

Children who had experienced an injection site reaction at 18 months of age were assigned randomly to receive an intramuscular injection of either reduced-antigen content diphtheria-tetanus-acellular pertussis vaccine or diphtheria-tetanus-acellular pertussis vaccine between 4 and 6 years of age. Children who developed extensive limb swelling were recruited for assessment by clinical examination; ultrasound studies of the affected and opposite (control) arms were performed 24 to 48 hours after immunization and 48 to 96 hours later.

RESULTS

Twelve children with extensive limb swelling were enrolled in the study. Ultrasound examinations demonstrated swelling of both the subcutaneous and muscle layers of the vaccinated arm. Ultrasound assessment showed that the swelling exceeded the clinical measurements of skin redness and swelling. Subcutaneous and muscle tissues expanded to 281% and 111% of the tissue thicknesses of the control arm, respectively. Repeat ultrasound examinations after 48 to 96 hours showed considerable resolution of muscle swelling, compared with subcutaneous tissue swelling. There was no significant difference in the extent of swelling detected between children who received diphtheria-tetanus-acellular pertussis vaccine and those who received reduced-antigen content diphtheria-tetanus-acellular pertussis vaccine.

CONCLUSION

Extensive limb swelling reactions after diphtheria-tetanus-acellular pertussis or reduced-antigen content booster immunizations involved swelling of subcutaneous and muscle tissues with swelling and duration more marked in subcutaneous tissue.

Immunogenicity and safety of a combined DTaP–IPV vaccine compared with separate DTaP and IPV vaccines when administered as pre-school booster doses with a second dose of MMR vaccine to healthy children aged 4–6 years

Combination vaccines represent one solution to the problem of increased numbers of injections during single clinic visits. A combined DTaP-IPV (Infanrix-IPV) vaccine has been developed for use as a pre-school booster. Four hundred healthy children aged 4-6 years previously primed with 4 doses of DTaP vaccine (Infanrix), 3 doses of poliovirus vaccine and 1 dose of MMR vaccine were randomized to receive single doses of either the combined DTaP-IPV vaccine or separate DTaP and IPV vaccines in a Phase II trial (DTaP-IPV-047). All children also received a second dose of MMR vaccine. Immunogenicity was assessed in serum samples taken before and 1 month after booster administration. Safety was actively assessed for 42 days post-vaccination. Non-inferiority of the DTaP-IPV vaccine to separate DTaP and IPV vaccines was demonstrated for all DTaP antigen booster response rates and poliovirus geometric mean titers of antibody ratios. Post-vaccination, > or =99.4% of children in both groups had seroprotective levels of anti-diphtheria and anti-tetanus antibodies (> or =0.1IU/mL) and seroprotective anti-poliovirus antibody titers (> or =1:8). All children in both groups were seropositive for measles, mumps and rubella antibodies, with similar post-vaccination geometric mean concentrations/titers. No significant differences were observed in the incidence of solicited local or general symptoms, unsolicited symptoms and serious adverse events between the two groups. This combined DTaP-IPV appeared safe and immunogenic when given as a booster dose at 4-6 years of age. The DTaP-IPV vaccine had no negative effect on the response to co-administered MMR vaccine, making it well-suited for use as a pre-school booster.