Human papillomavirus prevalence and type distribution in invasive cervical cancer in sub-Saharan Africa.

In sub-Saharan Africa, invasive cervical cancer (ICC) incidence and mortality are among the highest in the world. This cross-sectional epidemiological study assessed human papillomavirus (HPV) prevalence and type distribution in women with ICC in Ghana, Nigeria, and South Africa. Cervical biopsy specimens were obtained from women aged ≥ 21 years with lesions clinically suggestive of ICC. Histopathological diagnosis of ICC was determined by light microscopy examination of hematoxylin and eosin stained sections of paraffin-embedded cervical specimens; samples with a confirmed histopathological diagnosis underwent HPV DNA testing by polymerase chain reaction. HPV-positive specimens were typed by reverse hybridization line probe assay. Between October 2007 and March 2010, cervical specimens from 659 women were collected (167 in Ghana, 192 in Nigeria and 300 in South Africa); 570 cases were histologically confirmed as ICC. The tumor type was identified in 551/570 women with ICC; squamous cell carcinoma was observed in 476/570 (83.5%) cases. The HPV-positivity rate in ICC cases was 90.4% (515/570). In ICC cases with single HPV infection (447/515 [86.8%]), the most commonly detected HPV types were HPV16 (51.2%), HPV18 (17.2%), HPV35 (8.7%), HPV45 (7.4%), HPV33 (4.0%) and HPV52 (2.2%). The prevalence of single and multiple HPV infections seemed higher among HIV-positive women and HPV type distribution appeared to differ according to tumor type and HIV status. In conclusion, HPV16, 18, 45 and 35 were the most common HPV types in sub-Saharan African women with ICC and HPV infections were more common in HIV-positive women.

Prevalence and type distribution of human papillomavirus in cervical adenocarcinoma in Korean women.

BACKGROUND: An increase in incidence of cervical adenocarcinoma (CADC) has been reported in many countries, including Korea. However, few studies describe human papillomavirus (HPV) type distribution among CADC in Asia. OBJECTIVE AND METHODS: This was a retrospective, hospital-based observational study between 2005 and 2010 to estimate the overall prevalence and distribution of HPV types among CDAC in Korean women. The study used hematoxylin & eosin and immunohistochemical staining (for the two biomarkers p16 and progesterone receptor [PR]) to diagnose and subtype CADC samples. HPV DNA was amplified by polymerase chain reaction (PCR) and HPV genotypes were identified using reverse hybridization. RESULTS: Of 196 cases submitted, 89.3% of the cases were confirmed as CADC. The mean age at diagnosis was 47.1 (standard deviation [SD] 11.9) years. No statistically significant differences in mean age at diagnosis by histological subtype were found. HPV DNA was detected in 90.3% (177/196) of CADC. HPV-18 was the most prevalent type (54.2%), followed by HPV-16 (44.1%) and HPV-45 (3.4%). Infection with any high-risk HPV type was identified in 97.7% of HPV-DNA-positive CADC. The biomarker p16 was positive in 92% of CADC cases and PR was positive in 19.6% of CADC. CONCLUSION: HPV DNA was found in the large majority of CADC in Korean women, with HPV-18 being the most common type followed by HPV-16 and HPV-45. This study is among the first in Asia to specifically report HPV type distribution in CADC. This information will help inform policy decisions concerning HPV vaccination for the prevention of CADC.

Human papillomavirus type distribution in invasive cervical cancer and high-grade cervical intraepithelial neoplasia across 5 countries in Asia.

OBJECTIVE: Independent, prospective, multicenter, hospital-based cross-sectional studies were conducted across 5 countries in Asia, namely, Malaysia, Vietnam, Singapore, South Korea, and the Philippines. The objectives of these studies were to evaluate the prevalence of human papillomavirus (HPV) types (high risk and others including coinfections) in women with invasive cervical cancer (ICC) and high-grade precancerous lesions. METHODS: Women older than 21 years with a histologic diagnosis of ICC and cervical intraepithelial neoplasia [CIN 2 or 3 and adenocarcinoma in situ (AIS)] were enrolled. Cervical specimens were reviewed by histopathologists to confirm the presence of ICC or CIN 2/3/AIS lesion and tested with short PCR fragment 10-DNA enzyme immunoassay-line probe assay for 14 oncogenic HPV types and 11 non-oncogenic HPV types. The prevalence of HPV 16, HPV 18, and other high-risk HPV types in ICC [including squamous cell carcinoma (SCC) and adenocarcinoma/adenosquamous carcinoma (ADC/ASC)] and CIN 2/3/AIS was estimated. RESULTS: In the 5 Asian countries, diagnosis of ICC was confirmed in 500 women [SCC (n = 392) and ADC/ASC (n = 108)], and CIN 2/3/AIS, in 411 women. Human papillomavirus DNA was detected in 93.8% to 97.0% (84.5% for the Philippines) of confirmed ICC cases [94.0%-98.7% of SCC; 87.0%-94.3% (50.0% for the Philippines) of ADC/ASC] and in 93.7% to 100.0% of CIN 2/3/AIS. The most common types observed among ICC cases were HPV 16 (36.8%-61.3%), HPV 18 (12.9%-35.4%), HPV 52 (5.4%-10.3%), and HPV 45 (1.5%-17.2%), whereas among CIN 2/3/AIS cases, HPV 16 (29.7%-46.6%) was the most commonly observed type followed by HPV 52 (17.0%-66.7%) and HPV 58 (8.6%-16.0%). CONCLUSIONS: This article presents the data on the HPV prevalence, HPV type distribution, and their role in cervical carcinogenesis in 5 Asian countries. These data are of relevance to public health authorities for evaluating the existing and future cervical cancer prevention strategies including HPV-DNA testing-based screening and HPV vaccination in these Asian populations.

The burden of rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis among children aged less than 6 years in Japan: a retrospective, multicenter epidemiological survey.

BACKGROUND: Rotavirus is a leading worldwide cause of acute gastroenteritis in young children. This retrospective hospital-based study assessed the burden of rotavirus gastroenteritis in children younger than 6 years in Japan. METHODS: Children admitted to eight hospitals for acute gastroenteritis between 2008 and 2009 were identified from hospital admission databases. Diagnosis of acute gastroenteritis/rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis was confirmed based on either the International Classification of Diseases and Related Health Problems 10th revision (ICD10) codes (intestinal infectious diseases [AA00-AA09] and rotavirus gastroenteritis [A08.0]) or from rapid rotavirus diagnostic test results. RESULTS: Of 13,767 hospitalized children, 11.9% (1,644), 4.8% (665) and 0.6% (81) were diagnosed with acute gastroenteritis, rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis, respectively. Among acute gastroenteritis hospitalizations, 40.5% (665/1,644; ICD10 and rapid test) and 57.7% (645/1,118; rapid test only) were confirmed as rotavirus positive. Of 1,563 children with community-acquired acute gastroenteritis, 584 (37.4%) cases were confirmed as rotavirus positive. The median durations of hospitalization for all and community-acquired rotavirus gastroenteritis were 5.0 days (range: 2.0-133.0 days) and 5.0 days (range: 2.0-34.0 days), respectively. Among rotavirus gastroenteritis hospitalizations, 12.2% (81/665) of cases were hospital-acquired and the median duration of hospitalization was 10.0 days (range: 2.0-133.0 days). The median duration of additional hospitalization due to hospital-acquired rotavirus gastroenteritis was 3.0 days (range: 0-14 days). The overall incidence rate of hospital-acquired rotavirus gastroenteritis was 1.0 per 1,000 children hospital-days. The number of rotavirus gastroenteritis cases peaked between February and May in both 2008 and 2009, and the highest number of cases was reported in March 2008 (21.8%; 145/665). The highest number of rotavirus gastroenteritis hospitalizations (24.1%; 160/665) was observed in children aged 12-18 months. The proportion of hospital-acquired rotavirus gastroenteritis was higher in children aged below 18 months as compared to children at least 18 months of age (0.94 [95% CI: 0.71-1.21] vs. 0.39 [95% CI: 0.25-0.58]) and for children hospitalized for at least 5 days compared to those hospitalized for less than 5 days (0.91 [95% CI: 0.72-1.14] vs. 0.15 [95% CI: 0.05-0.32]). CONCLUSIONS: Both community- and hospital-acquired rotavirus gastroenteritis are significant public health problems in Japan. Data from this study justify the need for the introduction and implementation of rotavirus vaccination in the Japanese national immunization program. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01202201.

Safety and reactogenicity of DTPa-HBV-IPV/Hib and DTPa-IPV/I-Hib vaccines in a post-marketing surveillance setting.

Combination vaccines have been shown to improve the timeliness of vaccination and vaccine coverage. Safety and reactogenicity of combined diphtheria-tetanus-acellular pertussis-inactivated poliovirus and Haemophilus influenzae type b vaccine (DTPa-IPV/Hib, Infanrix IPV+Hib, GlaxoSmithKline Biologicals) was assessed in two clinical studies. In Study A, 2,590 subjects received DTPa-IPV/Hib at 3, 4 and 5 months of age with a booster at 18 months. In Study B, 702 subjects received the same schedule but with DTPa-hepatitis B-IPV/Hib (DTPa-HBV-IPV/Hib, Infanrix hexa, GlaxoSmithKline Biologicals) vaccine administered at 5 months of age. Reactogenicity was assessed for four days after each dose using diary cards. Serious adverse events (SAEs) were assessed until 24 months of age. The vaccines were well tolerated. After primary vaccination, irritability was the most frequently reported grade 3 general symptom (0.8% of doses in both studies). Fever (axillary) > 39 degrees C was infrequent (0.3% of doses in Study A; 0.5% of doses in Study B). After the booster dose, the most frequently reported grade 3 symptom was redness (5%) in Study A and pain (0.5%) in Study B. An axillary temperature > 39 degrees C was reported in 1.1% of subjects. Throughout the study period, 646 SAEs were reported, of which 6 SAEs were considered to be vaccination-related. The reactogenicity and safety profile of the combined DTPa-IPV/Hib vaccine was good when used for primary and booster vaccinations in over 3,000 Singaporean infants. Substitution of DTPa-IPV/Hib with DTPa-HBV-IPV/Hib at Month 5 reduced the number of injections required at this age by one.

Decennial administration of a reduced antigen content diphtheria and tetanus toxoids and acellular pertussis vaccine in young adults.

BACKGROUND: Booster vaccination against tetanus and diphtheria at 10-year intervals is commonly recommended. Reduced antigen content diphtheria and tetanus toxoids and acellular pertussis (dTpa) vaccines developed for booster vaccination of preschool children, adolescents, and adults are licensed for once-in-a-lifetime use in most countries. Objective. To evaluate decennial administration of a dTpa vaccine. Methods. Young adults vaccinated with dTpa or diphtheria and tetanus toxoids followed by acellular pertussis (DT+ap) 1 month later in a clinical trial 10 years previously received 1 dTpa dose. Blood samples were taken before and 1 month after vaccination. Antibody concentrations against vaccine antigens were measured by enzyme-linked immunosorbent assay. Solicited and unsolicited symptoms and serious adverse events were recorded. RESULTS: Eighty-two individuals were enrolled in the study. In the 75 individuals who had received the dTpa vaccine 10 years previously, prevaccination seroprotection or seropositivity rates were 98.8% (diphtheria), 97.5% (tetanus), 64.6% (pertussis toxoid), 100% (filamentous hemagglutinin), and 96.3% (pertactin). One month after the second booster, all study participants were seroprotected or seropositive against all vaccine antigens. Antibody concentrations increased by a similar magnitude as 10 years previously. During the 4-day follow-up, 9.9% of participants recorded grade 3 pain; 17.3% and 18.5% recorded redness and swelling of 50 mm or larger, respectively; and 8.6% recorded fever (temperature, 37.5 degrees C). No serious adverse events were considered causally related to the vaccine. CONCLUSIONS: A second dTpa booster was highly immunogenic and well tolerated in this population of young adults. This study supports the use of this vaccine as a decennial booster. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00610168 .

Lasting immune memory against hepatitis B in children after primary immunization with 4 doses of DTPa-HBV-IPV/Hib in the first and 2nd year of life.

BACKGROUND: Few studies have assessed long term persisting immunity against hepatitis B virus (HBV) in children vaccinated during infancy with combined vaccines containing recombinant HBV surface antigen (HBs). We assessed antibody persistence and immune memory in children 4-5 years of age, previously vaccinated with four doses of combined hexavalent DTPa-HBV-IPV/Hib vaccine (Infanrix hexa). METHODS: Immune memory was assessed in 301 children through administration of a challenge dose of monovalent HBV vaccine. RESULTS: At 4-5 years of age, 85.3% of subjects had persisting anti-HBs antibody concentrations >or= 10 mIU/mL, rising to 98.6% after the HBV challenge dose. All but 12 subjects (95.8%) achieved post-challenge anti-HBs concentrations >or= 100 mIU/mL. The post-challenge anti-HBs GMC rose by 100-fold compared to pre-challenge concentrations. An anamnestic response to the HBV vaccine challenge was observed in 96.8% of subjects, including 17/21 (81.0%) of children with initially undetectable antibodies (<3.3 mIU/mL). All but 4 of 42 subjects (90.5%) with anti-HBs antibodies <10 mIU/mL prior to the challenge dose, achieved seroprotective levels afterwards. A 4-fold rise in antibody concentration after the challenge dose was observed in 259/264 (98.1%) of initially seropositive subjects. The magnitude of the post-challenge responses was proportional to pre-challenge anti-HBs levels. No serious adverse events were reported during the study. CONCLUSION: The combined DTPa-HBV-IPV/Hib vaccine induced lasting immune memory against hepatitis B. Long term protection afforded by DTPa-HBV-IPV/Hib is likely to be similar to that observed following priming with monovalent HBV vaccines. TRIAL REGISTRATION: http://www.clinicaltrials.gov 106789 NCT00411697.

Immunogenicity, reactogenicity and safety of three-dose primary and booster vaccination with combined diphtheria-tetanus-whole-cell pertussis-hepatitis B-reduced antigen content Haemophilus influenzae type b vaccine in Filipino children.

OBJECTIVES: To evaluate the immunogenicity, reactogenicity and safety of primary and booster vaccination with DTPw-HBVLT/Hib2.5 vaccine containing low thiomersal and reduced quantities of Hib polysaccharide (PRP). BACKGROUND: Combined DTP vaccines have high global coverage. Thus, the addition of new antigens to existing DTP vaccines is the most effective way to ensure high coverage. METHODS: 192 healthy infants were randomized to receive the investigational DTPw-HBVLT/Hib2.5 vaccine or licensed DTPw-HBV/Hib10 at 6, 10, 14 weeks. Immune memory to the Hib antigen was assessed through administration of plain PRP challenge at 10 months in 50% of subjects. Challenged and unchallenged subjects respectively received a DTP-HBV or DTPa-HBV/Hib booster at 15-18 months of age. Antibody responses were measured using enzyme-linked immunosorbent assay (ELISA) and reactogenicity was assessed using diary cards. RESULTS: One month post-primary vaccination, 100% and ≥ 93.7% of subjects in both groups had anti-PRP antibody concentrations ≥ 0.15 µg/mL and ≥ 1.0 µg/mL, respectively. Robust responses to PRP were observed after the 10 month plain PRP challenge and booster responses were observed in unchallenged subjects after the booster dose at 15-18 months of age. Post-primary and post-booster responses to the other vaccine antigens were at least as high in the DTPw-HBVLT/Hib2.5 group versus the DTPw-HBV/Hib10 group. The reactogenicity profile of the DTPw-HBVLT/Hib2.5 vaccine was acceptable. CONCLUSION: The DTPw-HBVLT/Hib2.5 combination vaccine with reduced thiomersal and Hib content had equivalent immunogenicity and tolerability versus the full standard DTPw-HBV/Hib10 vaccine. DTPw-HBVLT/Hib2.5 or DTPw-HBV/Hib10 vaccines can contribute to reducing childhood diseases through ensuring high vaccine coverage in mass vaccination programs. ClinicalTrials.gov identifiers: NCT 01061541, NCT00158808.

Repeated administration of a reduced-antigen-content diphtheria-tetanus-acellular pertussis and poliomyelitis vaccine (dTpa-IPV; Boostrix™ IPV).

BACKGROUND: The rising incidence of pertussis amongst adults and adolescents in industrialized countries could be reduced by replacing tetanus and diphtheria (Td) boosters with reduced-antigen-content dT-acellular pertussis (dTpa)vaccines. Repeated administration of a dTpa-IPV (dTpa-inactivated poliomyelitis; BoostrixTM Polio, GlaxoSmithKline)booster to adolescents, 5 years after their previous dose was evaluated. RESULTS: Before the second dTpa-IPV booster, the percentage of subjects who were seroprotected/seropositive was: 98.2% (D); 98.5% (T); 40.6% (PT); 99.7% (FHA); 97.0% (PRN); 98.8% (anti-polio 1); 99.7% (anti-polio 2); 97.0% (anti-polio 3). One month after the second dTpa-IPV dose, all subjects were seroprotected against D, T and polio and anti-pertussis booster responses (seroconversion or ≥2-fold increase) were seen in 93.3% (PT), 93.4% (FHA) and 95.2% (PRN) of subjects.During 4-day follow-up, 4.1% subjects recorded grade 3 pain; 4.6% and 3.6% recorded redness or swelling >50 mm, respectively. No serious adverse events were recorded. The incidence of symptoms was not higher than after the previous booster. METHODS: 415 subjects (mean age 11.4 years) who had received either dTpa-IPV or dTpa + IPV at age 4­8 years, all received one dose of dTpa-IPV in this open, phase IV trial. Blood samples were taken before and one-month post-vaccination. Antibody concentrations against D, T, pertussis toxoid (PT), filamentous haemagglutinin (FHA), pertactin (PRN) and polio antigens were determined. Reactogenicity and safety was assessed. CONCLUSIONS: A second dTpa-IPV booster was highly immunogenic and well tolerated in this population of adolescents, supporting the repeated administration of BoostrixTM Polio. This study is registered at www.clinicaltrials.gov NCT00635128.

Hepatotropic viruses as etiological agents of acute liver failure and related-outcomes among children in India: a retrospective hospital-based study.

BACKGROUND: Acute liver failure (ALF) is marked by a sudden loss of hepatic function and is associated with a high mortality rate in children. The etiology of ALF is shown to vary geographically. This study assessed the frequency of hepatotropic viruses as etiological agents of ALF in Indian children. METHODS: This retrospective study enrolled children aged 0-18 years with confirmed ALF admitted to Christian Medical College, Vellore and King Edward Memorial Hospital and Research Center, Pune between January 2003 and December 2005. The frequency of hepatotropic viruses as etiological agents in children with ALF aged ≤18 years was calculated with 95% confidence interval (CI). Descriptive analyses of demographic characteristics, clinical signs and symptoms of ALF, choice of treatment and outcomes were performed. RESULTS: Of 76 children enrolled, 54 were included in the per-protocol analyses. Mean age of children with ALF was 5.43 years (standard deviation = 3.62); 51.9% (28/54) were female. The percentage of children positive for anti-hepatitis A virus (HAV) IgM and hepatitis B surface antigen was 65.9% (27/41; 95% CI 49.4-79.9) and 15.9% (7/44; 95% CI 6.6-30.1), respectively. The final cause of ALF was HAV (36.3%) followed by hepatitis B virus (HBV; 8.8%). Before and during admission, encephalopathy was observed in 77.8% (42/54) and 63.0% (34/54) of children, respectively. A high number of children (46/54; 85.2%) required intensive care and ALF was fatal in 24.1% (13/54). The proportion of deaths due to HAV and HBV was 18.5% (5/27) and 57.1% (4/7), respectively. CONCLUSIONS: HAV and HBV were the most common etiological agents of ALF in Indian children. Primary prevention by vaccination against HAV and HBV in young children may be useful in the prevention of ALF due to viral hepatitis in India.

Impact of rotavirus vaccination in Australian children below 5 years of age: a database study.

This study was conducted to assess the impact of administration of two-dose rotavirus (RV) vaccine (RIX4414; GlaxoSmithKline Vaccines) among children aged less than 5 y in three states/territories of Australia. Aggregated and de-identified data on rotavirus gastroenteritis (RVGE) and all-cause gastroenteritis (AGE) from July 1998-June 2009 were obtained from the Australian Institute of Health and Welfare database. The baseline incidence (July 1998-June 2006) of RVGE hospitalizations before RV vaccine introduction in New South Wales (NSW), the Australian Capital Territory (ACT) and the Northern Territory (NT) were 33.75, 42.93 and 288.67 per 10,000 child-years, respectively among children aged 0-11 mo. Following RV vaccine introduction in NSW, the ACT and the NT, incidence of RVGE hospitalizations reduced to 13.06, 17.35 and 47.52 per 10,000 child-years, respectively, during July 2007-June 2008 and 3.87, 8.40 and 122.79 per 10,000 child-years, respectively, during July 2008-June 2009 among children aged 0-11 mo. Reductions in RVGE and AGE were also observed in all children below 5 y of age in NSW and the ACT. Overall reduction in hospitalizations due to RVGE and AGE was observed following RV vaccine introduction into the NIP in Australia.

A hospital-based surveillance of rotavirus gastroenteritis in children <5 years of age in Singapore.

BACKGROUND: In Singapore, 2 rotavirus vaccines were licensed in October 2005 and July 2007, respectively, for vaccinating infants aged ≥ 6 weeks against rotavirus gastroenteritis. These vaccines are optional and are not included in the National Childhood Immunization Program. This study aimed to determine the incidence of rotavirus gastroenteritis-associated hospitalizations among children <5 years of age. METHODS: Children <5 years, who were hospitalized for acute gastro enteritis, were enrolled between September 2005 and April 2008. Stool samples were tested for the presence and serotyping of rotavirus. Incidence and proportion of gastroenteritis and rotavirus gastroenteritis cases were calculated with 95% confidence intervals. RESULTS: Among 1976 children included in the according-to-protocol cohort, 781 were rotavirus positive with a median age of 24 months (range: 0-59 months). The overall incidence of rotavirus gastroenteritis hospitalizations during the entire study period in children <5 years of age was 4.6 (95% confidence interval: 4.3-4.9) per 1000 person-years with the highest number of cases observed in children 13-24 months of age (26.5%). G1P[8] (18.3%) and G9P[8] (9.9%) were the most common rotavirus types. Rotavirus gastroenteritis hospitalizations peaked between January and March. CONCLUSION: Rotavirus infection was the primary cause of acute gastro enteritis hospitalizations among children <5 years of age, constituting nearly one-third of gastroenteritis hospitalizations in Singapore. The predominant strain observed in Singapore was G1P[8]. Results of this study suggest the need for implementation of rotavirus vaccination into National Childhood Immunization Program in Singapore.

A decennial booster dose of reduced antigen content diphtheria, tetanus, acellular pertussis vaccine (Boostrix™) is immunogenic and well tolerated in adults.

Reduced-antigen-content diphtheria-tetanus-acellular-pertussis (dTpa) vaccines are predominantly recommended for once-in-a-lifetime use. A second dTpa (Boostrix™, GlaxoSmithKline Biologicals) administration in 164 adults previously vaccinated with dTpa 10 years previously was evaluated. Before the decennial booster, 89.4% and 94.8% subjects were seroprotected (antibodies ≥0.1 IU/mL) for diphtheria and tetanus, respectively. One-month post-booster, all subjects were seroprotected/seropositive against all vaccine antigens. Robust GMC increases indicated a booster response similar to the first booster. The decennial booster was well tolerated without serious adverse events, consistent with product experience. This study supports replacing traditional Td boosters with dTpa, and use of Boostrix™ as a decennial booster. This study is registered at www.clinicaltrials.com NCT00548171.

Booster vaccination against pertussis in Chinese children at six years of age using reduced antigen content diphtheria-tetanus-acellular pertussis vaccine (Boostrix()).

Pertussis continues to circulate in Chinese communities and older children, adolescents and adults are sources of infection for unprotected infants. Two studies conducted in Jiangsu Province in the People's Republic of China assessed the immunogenicity, reactogenicity and safety of Boostrix(), a combined reduced antigen content diphtheria-tetanus-acellular pertussis vaccine (dTpa) when administered as a booster dose to children 6 to 8 years of age. Immunogenicity was assessed before and one month after vaccination in a subset. Reactogenicity was assessed over a 4-day follow-up using diary cards. A total of 690 Chinese subjects were enrolled. Boostrix() was well tolerated. One month after the booster dose, 100% of dTpa recipients had seroprotective antibody concentrations against diphtheria and tetanus. The percentage of subjects with a response against pertussis antigens (using locally defined cut-offs) was 91.9% for pertussis toxoid, 98.8% for filamentous hemagglutinin, and 100% for pertactin. The exploratory analysis showed no statistically significant differences between dTpa or diphtheria-tetanus vaccine in terms of the percentage of subjects with seroprotective antibodies against diphtheria or tetanus. These studies demonstrate that Boostrix() is well tolerated and immunogenic when administered as a booster dose to 6 to 8 year old Chinese children previously immunized with a combined diphtheria-tetanus-pertussis vaccine. Introduction of dTpa into the routine Chinese immunization schedule would provide booster vaccination against pertussis without the addition of further injections into the Chinese vaccination schedule and is likely to promote improved pertussis control in older children.