Immunogenicity and safety of four different doses of Haemophilus influenzae type b-tetanus toxoid conjugated vaccine, combined with diphtheria–tetanus–pertussis vaccine (DTP-Hib), in Indonesian infants

The roles of CD4+ T cell help, sex, and dose in the induction of protective CD8+ T cells against a lethal poxvirus by mRNA-LNP vaccines

The role of CD4+ T cells in the induction of protective CD8+ T cells by mRNA lipid nanoparticle (LNP) vaccines is unknown. We used B6 or Tlr9 -/- mice depleted or not of CD4+ T cells and LNP vaccines loaded with mRNAs encoding the ectromelia virus (ECTV) MHC class I H-2 Kb-restricted immunodominant CD8+ T cell epitope TSYKFESV (TSYKFESV mRNA-LNPs) or the ECTV EVM158 protein, which contains TSYKFESV (EVM-158 mRNA-LNPs). Following prime and boost with 10 μg of either vaccine, Kb-TSYKFESV-specific CD8+ T cells fully protected male and female mice from ECTV at 29 (both mRNA-LNPs) or 90 days (EVM158 mRNA-LNPs) post boost (dpb) independently of CD4+ T cells. However, at 29 dpb with 1 μg mRNA-LNPs, males had lower frequencies of Kb-TSYKFESV-specific CD8+ T cells and were much less well protected than females from ECTV, also independently of CD4+ T cells. At 90 dpb with 1 μg EVM158 mRNA-LNPs, the frequencies of Kb-TSYKFESV-specific CD8+ T cells in males and females were similar, and both were similarly partially protected from ECTV, independently of CD4+ T cells. Therefore, at optimal or suboptimal doses of mRNA-LNP vaccines, CD4+ T cell help is unnecessary to induce protective anti-poxvirus CD8+ T cells specific to a dominant epitope. At suboptimal doses, protection of males requires more time to develop.

Factors That Influence the Immune Response to Vaccination

There is substantial variation between individuals in the immune response to vaccination. In this review, we provide an overview of the plethora of studies that have investigated factors that influence humoral and cellular vaccine responses in humans. These include intrinsic host factors (such as age, sex, genetics, and comorbidities), perinatal factors (such as gestational age, birth weight, feeding method, and maternal factors), and extrinsic factors (such as preexisting immunity, microbiota, infections, and antibiotics). Further, environmental factors (such as geographic location, season, family size, and toxins), behavioral factors (such as smoking, alcohol consumption, exercise, and sleep), and nutritional factors (such as body mass index, micronutrients, and enteropathy) also influence how individuals respond to vaccines. Moreover, vaccine factors (such as vaccine type, product, adjuvant, and dose) and administration factors (schedule, site, route, time of vaccination, and coadministered vaccines and other drugs) are also important. An understanding of all these factors and their impacts in the design of vaccine studies and decisions on vaccination schedules offers ways to improve vaccine immunogenicity and efficacy.

Combination vaccines against diarrheal diseases

Diarrheal diseases remain a leading cause of global childhood mortality and morbidity. Several recent epidemiological studies highlight the rate of diarrheal diseases in different parts of the world and draw attention to the impact on childhood growth and survival. Despite the well-documented global burden of diarrheal diseases, currently there are no combination diarrheal vaccines, only licensed vaccines for rotavirus and cholera, and Salmonella typhi-based vaccines for typhoid fever. The recognition of the impact of diarrheal episodes on infant growth, as seen in resource-poor countries, has spurred action from governmental and non-governmental agencies to accelerate research toward affordable and effective vaccines against diarrheal diseases. Both travelers and children in endemic countries will benefit from a combination diarrheal vaccine, but it can be argued that the greater proportion of any positive impact will be on the public health status of the latter. The history of combination pediatric vaccines indicate that monovalent or single disease vaccines are typically licensed first prior to formulation in a combination vaccine, and that the combinations themselves undergo periodic revision in response to need for improvement in safety or potential for wider coverage of important pediatric pathogens. Nevertheless combination pediatric vaccines have proven to be an effective tool in limiting or eradicating communicable childhood diseases worldwide. The landscape of diarrheal vaccine candidates indicates that there now several in active development that offer options for potential testing of combinations to combat those bacterial and viral pathogens responsible for the heaviest disease burden—rotavirus, ETEC, Shigella, Campylobacter, V. cholera and Salmonella.

Acute respiratory infections among under-5 children in India: A situational analysis

Acute respiratory infections (ARIs) are the leading cause of death among children less than 5 years in India. Emergence of newer pathogenic organisms, reemergence of disease previously controlled, wide spread antibiotic resistance, and suboptimal immunization coverage even after many innovative efforts are major factors responsible for high incidence of ARI. Drastic reduction in the burden of ARI by low-cost interventions such as hand washing, breast feeding, availability of rapid and feasible array of diagnostics, and introduction of pentavalent vaccine under National Immunization Schedule which are ongoing are necessary for reduction of ARI.

Naturally acquired and conjugate vaccine-induced antibody to Haemophilus influenzae type b (Hib) polysaccharide in Malian children: serological assessment of the Hib immunization program in Mali

Haemophilus influenzae type b (Hib) conjugate vaccine for infants (6, 10, and 14 weeks of age) was introduced into the Malian Expanded Program on Immunization in July 2005, to diminish invasive Hib disease in young children. Antibodies to Hib capsular polysaccharide (PRP) were measured in infants and toddlers from an area already served by the Hib immunization program (Bamako) and in unimmunized children of the same age in a district (Kangaba) where Hib immunization had not yet begun. Among vaccinated Bamako children 6-23 months of age, 77-93% exhibited PRP titers ≥ 1.0 μg/mL, indicating long-term protection, versus only 10-23% of Kangaba children of that age. High PRP antibody titers in immunized children persisted through 2 years of age. Moreover, ∼50% of Bamako children exhibited anti-PRP titers ≥ 5.0 μg/mL; a level that impedes Hib upper respiratory carriage, and may thereby diminish the Hib transmission to the unimmunized susceptible population (i.e., providing indirect protection).

Safety reporting in developing country vaccine clinical trials-a systematic review

With more vaccines becoming available worldwide, vaccine research is on the rise in developing countries. To gain a better understanding of safety reporting from vaccine clinical research in developing countries, we conducted a systematic review in Medline and Embase (1989-2011) of published randomized clinical trials (RCTs) reporting safety outcomes with ≥50% developing country participation (PROSPERO systematic review registration number: CRD42012002025). Developing country vaccine RCTs were analyzed with respect to the number of participants, age groups studied, inclusion of safety information, number of reported adverse events following immunization (AEFI), type and duration of safety follow-up, use of standardized AEFI case definitions, grading of AEFI severity, and the reporting of levels of diagnostic certainty for AEFI. The systematic search yielded a total number of 50 randomized vaccine clinical trials investigating 12 different vaccines, most commonly rotavirus and malaria vaccines. In these trials, 94,459 AEFI were reported from 446,908 participants receiving 735,920 vaccine doses. All 50 RCTs mentioned safety outcomes with 70% using definitions for at least one AEFI. The most commonly defined AEFI was fever (27), followed by local (16) and systemic reactions (14). Logistic regression analysis revealed a positive correlation between the implementation of a fever case definition and the reporting rate for fever as an AEFI (p=0.027). Overall, 16 different definitions for fever and 7 different definitions for erythema were applied. Predefined AEFI case definitions by the Brighton Collaboration were used in only two out of 50 RCTs. The search was limited to RCTs published in English or German and may be missing studies published locally. The reported systematic review suggests room for improvement with respect to the harmonization of safety reporting from developing country vaccine clinical trials and the implementation of standardized case definitions.

A comparative study to evaluate the safety and immunogenicity of two lots of Haemophilus influenzae type-B conjugate vaccine manufactured at different scales

OBJECTIVE

To compare the immunogenicity and safety of two different lots of SII Haemophilus influenzae type-B-tetanus toxoid conjugate (SII HibP(RO)) vaccine manufactured at different scales when given in 3-dose schedule.

DESIGN

Phase IV, open label, comparative, randomized parallel group study.

SETTING

Shirdi Sai Baba Hospital, Vadu Budruk, Pune and Pediatrics Department of King Edward Memorial Hospital Research Centre, Pune.

SUBJECTS

204 normal healthy infants of age 6-8 weeks at the time of first vaccination.

METHODS

The eligible subjects received 3 doses of 0.5 ml of SII HibP(RO) vaccine of either lot depending upon randomization number, intramuscularly in right thigh in the EPI schedule of 6, 10 and 14 weeks. They also received concomitantly DTP-HB vaccine intramuscularly on left thigh and Oral Polio vaccine (OPV). Solicited reactions were captured for 7 days following each vaccination; the events beyond 7 days till day 28 were captured as unsolicited adverse events. Serious Adverse Events (SAEs) were looked for throughout the subject participation. Blood samples were collected at baseline (before the first dose) and one month after the third dose for anti-PRP (polyribosylribitol phosphate) antibodies.

RESULTS

In both groups, more than 98% subjects achieved short-term seroprotection (anti-PRP ≥ 0.15 μg/ml) after 3 doses. The long-term seroprotection (anti-PRP ≥ 1 μg/ml) was 87% and 80% in infants receiving lot manufactured at industrial scale and small scale respectively. Short and long term seroprotection and GMTs increased significantly as compared to baseline in both the groups. Overall local pain (52% and 58%), redness (30% and 41%), swelling (34% and 44%), fever (6% and 6%) and irritability (52% and 50%) were reported in infants receiving lot manufactured at industrial scale and small scale respectively. Majority of the reactions were mild and resolved without any sequelae. Four SAEs, none of them causally related to the study vaccine, occurred during study.

CONCLUSION

SII HibP(RO) vaccines manufactured in small and industrial scale are equally immunogenic, safe and confer adequate seroprotection to infants of 6-14 weeks of age. Scaling up production process has not affected the safety and immune response in the target population.

The first experimental study on a candidate combined vaccine against hepatitis A and hepatitis E

To test the possibility of developing a combined vaccine against hepatitis A and E, groups of mice were immunized with different formulations containing different dosages of a commercially inactivated hepatitis A vaccine and a candidate recombinant hepatitis E vaccine. Monovalent vaccine components were used as controls. The experimental results showed that the combined vaccine could induce neutralizing antibodies against both hepatitis A virus (HAV) and hepatitis E virus (HEV) effectively in mice. Moreover, the inactivated hepatitis A vaccine could increase the immunogenicity of the recombinant HEV protein, and the recombinant HEV protein had no adverse effects on the immunogenicity of the inactivated HAV vaccine. Thus, the present study demonstrates an important first step for the further development of a combined hepatitis A and E vaccine.