Lot-to-lot Consistency, Safety, Tolerability and Immunogenicity of an Investigational Hexavalent Vaccine in US Infants.

BACKGROUND: This multicenter phase III study (NCT01340937) evaluated the consistency of immune responses to 3 separate lots of diphtheria-tetanus toxoids-acellular pertussis 5, inactivated poliovirus vaccine, Haemophilus influenzae type b, and hepatitis B (DTaP5-IPV-Hib-HepB), an investigational hexavalent vaccine (HV). METHODS: Healthy infants were randomized (2:2:2:1) to receive HV or Pentacel (Control). Groups 1, 2 and 3 received HV at 2, 4 and 6 months, and Control at 15 months. Group 4 received Control at 2, 4, 6 and 15 months, plus Recombivax HB (HepB) at 2 and 6 months. Concomitant Prevnar 13 was given to all groups at 2, 4, 6 and 15 months; pentavalent rotavirus vaccine (RV5) was given to all groups at 2, 4 and 6 months. Blood specimens (3-5 mL) were collected immediately before administration of dose 1, postdose 3, immediately before toddler dose, and after toddler dose. Adverse events were recorded after each vaccination. RESULTS: The 3 manufacturing lots of HV induced consistent antibody responses to all antigens. Immunogenicity of HV was noninferior to Control for all antibodies, except for pertussis filamentous hemagglutinin geometric mean concentration postdose 3, and pertussis pertactin (PRN) geometric mean concentration after toddler dose. Postdose 3 immunogenicity of concomitantly administered Prevnar 13 was generally similar (except for serotype 6B) when given with HV or Control. Adverse events of HV were similar to Control, except for a higher rate of fever ≥38.0°C [49.2% vs. 35.4%, estimated difference 13.7% (8.4, 18.8)]. CONCLUSIONS: HV demonstrated lot-to-lot manufacturing consistency; safety and immunogenicity were comparable with the licensed vaccines. HV provides a new combination vaccine option within the US 2-month, 4-month and 6-month vaccine series.

Defining the optimal formulation and schedule of a candidate toxoid vaccine against Clostridium difficile infection: A randomized Phase 2 clinical trial.

BACKGROUND: Clostridium difficile, a major cause of nosocomial and antibiotic-associated diarrhea, carries a significant disease and cost burden. This study aimed to select an optimal formulation and schedule for a candidate toxoid vaccine against C. difficile toxins A and B. METHODS: Randomized, placebo-controlled, two-stage, Phase 2 study in a total of 661 adults aged 40-75 years. Stage I: low (50 µg antigen) or high (100 µg antigen) dose with or without aluminum hydroxide (AlOH) adjuvant, or placebo, administered on Days 0-7-30. Stage II: Days 0-7-30, 0-7-180, and 0-30-180, using the formulation selected in Stage I through a decision tree defined a priori and based principally on a bootstrap ranking approach. Administration was intramuscular. Blood samples were obtained on Days 0, 7, 14, 30, 60 (Stage I and II), 180, and 210 (Stage II); IgG to toxins A and B was measured by ELISA and in vitro functional activity was measured by toxin neutralizing assay (TNA). Safety data were collected using diary cards. RESULTS: In Stage I the composite immune response against toxins A and B (percentage of participants who seroconverted for both toxins) was highest in the high dose+adjuvant group (97% and 92% for Toxins A and B, respectively) and was chosen for Stage II. In Stage II the immune response profile for this formulation through Day 180 given on Days 0-7-30 ranked above the other two administration schedules. There were no safety issues. CONCLUSIONS: The high dose+adjuvant (100 µg antigen+AlOH) formulation administered at 0-7-30 days elicited the best immune response profile, including functional antibody responses, through Day 180 and was selected for use in subsequent clinical trials.

Epidemiology of Clostridium difficile: a hospital-based descriptive study in Argentina and Mexico.

A prospective study was conducted in four tertiary hospitals in Argentina and Mexico in order to describe the occurrence of Clostridium difficile infection (CDI) in these settings. The objective was to evaluate the incidence of CDI in at-risk populations in Argentina (one center) and Mexico (three centers) and to further explore potential study sites for vaccine development in this region. A prospective, descriptive, CDI surveillance study was conducted among hospitalized patients aged ≥40 years who had received ≥48h of antibiotic treatment. Stool samples were collected from those with diarrhea within 30 days after starting antibiotics and analyzed for toxins A and B by ELISA, and positive samples were further tested by toxinogenic culture and restriction endonuclease analysis type assay. Overall, 466 patients were enrolled (193 in Argentina and 273 in Mexico) of whom 414 completed the follow-up. Of these, 15/414 (3.6%) experienced CDI episodes occurring on average 18.1 days after admission to hospital and 15.9 days after the end of antibiotics treatment. The incidence rate of CDI was 3.1 (95% CI 1.7-5.2) per 1000 patient-days during hospitalization, and 1.1 (95% CI 0.6-1.8) per 1000 patient-days during the 30-day follow-up period. This study highlighted the need for further evaluation of the burden of CDI in both countries, including the cases occurring after discharge from hospital.

Immunogenicity, Safety, and Tolerability of a Hexavalent Vaccine in Infants.

BACKGROUND: DTaP5-IPV-Hib-HepB is a fully liquid investigational hexavalent vaccine directed against 6 diseases. METHODS: This multicenter, open-label, comparator-controlled, phase III study randomly assigned healthy infants 2-to-1 as follows: group 1 received DTaP5-IPV-Hib-HepB, PCV13, and RV5 at 2, 4, and 6 months of age followed by DTaP5, Hib-OMP, and PCV13 at 15 months of age; group 2 received DTaP5-IPV/Hib, PCV13, and RV5 at 2, 4, and 6 months of age, with HepB at 2 and 6 months of age, followed by DTaP5, Hib-TT, and PCV13 at 15 months of age. RESULTS: Overall, 981 participants were vaccinated in group 1 and 484 in group 2. Immune responses in group 1 to all antigens contained in DTaP5-IPV-Hib-HepB 1 month after dose 3 and for concomitant rotavirus vaccine were noninferior to those in group 2, with the exception of antipertussis filamentous hemagglutinin (FHA) geometric mean concentrations (GMCs). Vaccine response rates for FHA were noninferior to control. After the toddler dose, group 1 immune responses were noninferior to group 2 for all pertussis antigens. Solicited adverse event rates after any dose were similar in both groups, with the exceptions of increased injection-site erythema, increased fever, and decreased appetite in group 1. Fever was not associated with hospitalization or seizures. CONCLUSIONS: The safety and immunogenicity of DTaP5-IPV-Hib-HepB are comparable with the analogous licensed component vaccines. Decreased FHA GMCs and increased injection-site reactions and fever are unlikely to be clinically significant. DTaP5-IPV-Hib-HepB provides a new combination vaccine option aligned with the recommended US infant immunization schedule.

Clostridium difficile: development of a novel candidate vaccine.

Clostridium difficile has become the most frequent hospital-acquired infection in North America and the EU. C. difficile infection (CDI) is present worldwide and disease awareness is increasing. In the US, EU, and Canada, in addition to hospital diagnosed disease, CDI has also been reported with increasing frequency in the community. Hypervirulent strains have increased the morbidity and mortality associated with CDI. Current treatment options are suboptimal. Of all patients treated for CDI, 20% relapse and 65% of those experiencing a second relapse become chronic cases. An association between increased serum levels of IgG antibody against toxin A and asymptomatic carriage of C. difficile provides a rationale for vaccine development. Sanofi Pasteur's C. difficile candidate vaccine is being developed for the prevention of primary disease. The target population is adults at risk of CDI, those with planned hospitalization, long-term care/nursing home residents, and adults with co-morbidities requiring frequent/prolonged antibiotic use.

Phase I dose finding studies of an adjuvanted Clostridium difficile toxoid vaccine.

Fifty healthy adult (18-55 years) and 48 elderly (≥ 65 years) volunteers were randomized to receive a candidate Clostridium difficile toxoid vaccine (2 µg, 10 µg, or 50 µg) or placebo on Days 0, 28, and 56. No volunteer receiving placebo seroconverted. For toxin A, seroconversion by Day 56 (post-dose 2) was observed in 100% of volunteers aged 18-55 years in all dose groups and in 50%, 89%, and 100% of elderly participants in the 2 µg, 10 µg, and 50 µg dose groups, respectively. For both age groups, seroconversion for toxin B was lower than toxin A. There were no safety concerns.

Epidemiology of Clostridium difficile: a hospital-based descriptive study in Argentina and Mexico

A prospective study was conducted in four tertiary hospitals in Argentina and Mexico in order to describe the occurrence of Clostridium difficile infection (CDI) in these settings. The objective was to evaluate the incidence of CDI in at-risk populations in Argentina (one center) and Mexico (three centers) and to further explore potential study sites for vaccine development in this region. A prospective, descriptive, CDI surveillance study was conducted among hospitalized patients aged ≥40 years who had received ≥48 h of antibiotic treatment. Stool samples were collected from those with diarrhea within 30 days after starting antibiotics and analyzed for toxins A and B by ELISA, and positive samples were further tested by toxinogenic culture and restriction endonuclease analysis type assay. Overall, 466 patients were enrolled (193 in Argentina and 273 in Mexico) of whom 414 completed the follow-up. Of these, 15/414 (3.6%) experienced CDI episodes occurring on average 18.1 days after admission to hospital and 15.9 days after the end of antibiotics treatment. The incidence rate of CDI was 3.1 (95% CI 1.7-5.2) per 1000 patient-days during hospitalization, and 1.1 (95% CI 0.6-1.8) per 1000 patient-days during the 30-day follow-up period. This study highlighted the need for further evaluation of the burden of CDI in both countries, including the cases occurring after discharge from hospital.

Short communication: HIV type 1 genetic diversity among tea plantation workers in Kericho, Kenya.

In preparation for HIV-1 vaccine trials in Kenya, 2801 study volunteers, from a tea plantation in Kericho, were recruited as part of a prospective vaccine cohort development study. Cryopreserved plasma was available from 401 HIV-positive volunteers, and was the source of viral RNA for genotyping by the multiregion hybridization assay (MHA). Logistic regression was performed to determine association of risk factors and HIV-1 recombinant and dual infections. At baseline, HIV-1 subtype A was the dominant circulating pure subtype (56%), followed by subtype D (10%) and C (5%). Recombinant HIV-1 strains accounted for almost one-third of all infections (29%), with 7% infected with a dual strain of the HIV-1 variants described. A higher number of HIV-1 recombinant and dual infections was observed among volunteers who were 18-24 and 25-29 years of age, affiliated with the Luo tribe, had been married two or more times, reported not being circumcised, and had STI symptoms in the past 6 months. Adjusted odds ratios (AOR) significantly associated with HIV-1 recombinant and dual infection were age difference from current spouse (5-9 years; AOR = 2.5, 95% CI = 1.2-5.3 and > or = 10 years; AOR = 3.1, 95% CI = 1.5-6.4) and reported STI symptoms in the past 6 months (AOR = 4.8, 95% CI = 2.0-11.6), respectively. In conclusion, our results suggest that there is considerable heterogeneity with respect to HIV-1 subtype diversity in this population that should be considered in the planning for future vaccine trials in the region.

Epidemiology of HIV-1 infection in agricultural plantation residents in Kericho, Kenya: preparation for vaccine feasibility studies.

A cross-sectional study was performed to determine the prevalence and risk factors for HIV-1 infection among agricultural plantation residents in Kericho, Kenya. Volunteers were recruited, interviewed, and phlebotomized for HIV-1 serologic testing. Sex-specific adjusted odds ratios were estimated using logistic regression. The overall HIV-1 prevalence was 9.9% (81/820), with prevalence in women more than twice that in men (17.4% vs 8.0%, P=0.001). Among men, elevated HIV-1 prevalence was seen with increasing age, peaking in those older than 30 years (10.3%), marriage (10.4%), Luo tribe affiliation (23.5%), employment (8.9%), travel (11.0%), and being uncircumcised (29.2%). Among women, elevated HIV-1 prevalence was seen in those with no formal education (36.8%) and those who received goods in exchange for sex (36.0%). More than 97% of volunteers expressed a willingness to participate in future HIV-1 studies requiring semiannual visits. HIV prevention efforts have been implemented, along with further research to characterize this population for future cohort feasibility studies and HIV-1 vaccine efficacy trials.

The impact of HIV/AIDS on labour productivity in Kenya.

OBJECTIVES: To estimate the impact of HIV/AIDS on individual labour productivity during disease progression. METHODS: We used a retrospective cohort design to study the productivity and attendance of tea estate workers who died or were medically retired because of AIDS-related causes between 1997 and 2002 in western Kenya. We compared daily output in kilograms of tea leaves plucked, use of paid and unpaid leave and assignment to less strenuous tasks by 54 workers who died or were medically retired because of AIDS to those of comparison workers, matched on time and tea field using longitudinal regression. RESULTS: HIV-positive workers plucked less tea in the 18 months preceding AIDS-related termination and used more leave in the 3 years before termination. After adjusting for age and environmental factors, cases plucked between 4.11 and 7.93 kg/day less in the last year and a half before termination. Cases used between 9.2 and 11.0 more sick leave days, between 6.4 and 8.3 more annual leave days, between 19.9 and 11.8 more casual leave days, and spent between 19.2 and 21.8 more days doing less strenuous tasks in the 2 years before termination than did comparison pluckers. Tea pluckers who terminated because of AIDS-related causes earned 16.0% less in their second year before termination and 17.7% less in the year before termination. CONCLUSION: These results provide empirical estimates of the impact of HIV/AIDS on labour productivity. As workers often bring unrecorded 'helpers', actual differences may be greater. Decreased attendance and output may put sick workers in jeopardy of losing their jobs and impose financial burdens on employers.

Use of rapid and conventional testing technologies for human immunodeficiency virus type 1 serologic screening in a rural Kenyan reference laboratory.

We report a prospective comparison of human immunodeficiency virus type 1 testing by enzyme immunoassay and Western blot with four rapid tests of 486 subjects performed in rural Kenya. Rapid test sensitivity was 100%. Specificity ranged from 99.1 to 100%. Combined use of two Food and Drug Administration-approved rapid tests yielded a single false-positive result.