Search

WHO convened an Advisory Group (AG) to consider the feasibility, potential value, and limitations of establishing a closely-monitored challenge model of experimental severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) in healthy adult volunteers. The AG included experts in design, establishment, and performance of challenges. This report summarizes issues that render a COVID-19 model daunting to establish (the potential of SARS-CoV-2 to cause severe/fatal illness, its high transmissibility, and lack of a "rescue treatment" to prevent progression from mild/moderate to severe clinical illness) and it proffers prudent strategies for stepwise model development, challenge virus selection, guidelines for manufacturing challenge doses, and ways to contain SARS-CoV-2 and prevent transmission to household/community contacts. A COVID-19 model could demonstrate protection against virus shedding and/or illness induced by prior SARS-CoV-2 challenge or vaccination. A limitation of the model is that vaccine efficacy in experimentally challenged healthy young adults cannot per se be extrapolated to predict efficacy in elderly/high-risk adults.

Vaccines are increasingly based on new constructs, new technologies, and new compounds. Novel immunization programs are rapidly implemented globally. In this article, we highlight selected hot topics of this highly dynamic and broad field of scientific and public health development. The first section focuses on novel vaccines including malaria, dengue, serogroup B meningococcal, and respiratory syncytial virus vaccines and antibodies. The second section is addressing emerging strategies and programmatic challenges including maternal immunization, integrated mother-child safety monitoring, and finally coping strategies with vaccine shortages.Copyright © 2018, The American College of Clinical Pharmacology

Vaccines are increasingly based on new constructs, new technologies, and new compounds. Novel immunization programs are rapidly implemented globally. In this article, we highlight selected hot topics of this highly dynamic and broad field of scientific and public health development. The first section focuses on novel vaccines including malaria, dengue, serogroup B meningococcal, and respiratory syncytial virus vaccines and antibodies. The second section is addressing emerging strategies and programmatic challenges including maternal immunization, integrated mother-child safety monitoring, and finally coping strategies with vaccine shortages.

Vaccines are increasingly based on new constructs, new technologies, and new compounds. Novel immunization programs are rapidly implemented globally. In this article, we highlight selected hot topics of this highly dynamic and broad field of scientific and public health development. The first section focuses on novel vaccines including malaria, dengue, serogroup B meningococcal, and respiratory syncytial virus vaccines and antibodies. The second section is addressing emerging strategies and programmatic challenges including maternal immunization, integrated mother-child safety monitoring, and finally coping strategies with vaccine shortages.Copyright © 2018, The American College of Clinical Pharmacology

BACKGROUND: A 9-valent human papillomavirus-6/11/16/18/31/33/45/52/58 (9vHPV) vaccine extends coverage to 5 next most common oncogenic types (31/33/45/52/58) in cervical cancer versus quadrivalent HPV (qHPV) vaccine. We describe efficacy, immunogenicity, and safety in Asian participants (India, Hong Kong, South Korea, Japan, Taiwan, and Thailand) from 2 international studies: a randomized, double-blinded, qHPV vaccine-controlled efficacy study (young women aged 16-26 years; NCT00543543; Study 001); and an immunogenicity study (girls and boys aged 9-15 years; NCT00943722; Study 002). METHODS: Participants (N = 2519) were vaccinated at day 1 and months 2 and 6. Gynecological samples (Study 001 only) and serum were collected for HPV DNA and antibody assessments, respectively. Injection-site and systemic adverse events (AEs) were monitored. Data were analyzed by country and vaccination group. RESULTS: 9vHPV vaccine prevented HPV-31/33/45/52/58-related persistent infection with 90.4%-100% efficacy across included countries. At month 7, ≥97.9% of participants seroconverted for each HPV type. Injection-site AEs occurred in 77.7%-83.1% and 81.9%-87.5% of qHPV and 9vHPV vaccine recipients in Study 001, respectively, and 62.4%-85.7% of girls/boys in Study 002; most were mild to moderate. CONCLUSIONS: The 9vHPV vaccine is efficacious, immunogenic, and well tolerated in Asian participants. Data support 9vHPV vaccination programs in Asia. CLINICAL TRIALS REGISTRATION: NCT00543543; NCT00943722.

Vaccines are increasingly based on new constructs, new technologies, and new compounds. Novel immunization programs are rapidly implemented globally. In this article, we highlight selected hot topics of this highly dynamic and broad field of scientific and public health development. The first section focuses on novel vaccines including malaria, dengue, serogroup B meningococcal, and respiratory syncytial virus vaccines and antibodies. The second section is addressing emerging strategies and programmatic challenges including maternal immunization, integrated mother-child safety monitoring, and finally coping strategies with vaccine shortages.

BACKGROUND: The immunogenicity profile of the 9-valent HPV (9vHPV) vaccine was evaluated across five phase III clinical studies conducted in girls and boys 9-15 years of age and young women 16-26 years of age. The effect of baseline characteristics of subjects on vaccine-induced HPV antibody responses was assessed. METHODS: Immunogenicity data from 11,304 subjects who received ≥1 dose of 9vHPV vaccine in five Phase III studies were analyzed. Vaccine was administered as a 3-dose regimen. HPV antibody titers were assessed 1 month after dose 3 using a competitive Luminex immunoassay and summarized as geometric mean titers (GMTs). Covariates examined were age, gender, race, region of residence, and HPV serostatus and PCR status at day 1. RESULTS: GMTs to all 9 vaccine HPV types decreased with age at vaccination initiation, and were otherwise generally similar among the demographic subgroups defined by gender, race and region of residence. For all subgroups defined by race or region of residence, GMTs were higher in girls and boys than in young women. Vaccination of subjects who were seropositive at day 1 to a vaccine HPV type resulted in higher GMTs to that type, compared with those in subjects who were seronegative for that type at day 1. CONCLUSIONS: 9vHPV vaccine immunogenicity was robust among subjects with differing baseline characteristics. It was generally comparable across subjects of different races and from different regions. Greater immunogenicity in girls and boys versus young women (the population used to establish 9vHPV vaccine efficacy in clinical studies) indicates that the anti-HPV responses generated by the vaccine in adolescents from all races or regions were sufficient to induce high-level protective efficacy. This immunogenicity profile supports a widespread 9vHPV vaccination program and early vaccination.

The adaptive immune response to vaccination or infection can lead to the production of specific antibodies to neutralize the pathogen or recruit innate immune effector cells for help. The non-neutralizing role of antibodies in stimulating effector cell responses may have been a key mechanism of the protection observed in the RV144 HIV vaccine trial. In an extensive investigation of a rich set of data collected from RV144 vaccine recipients, we here employ machine learning methods to identify and model associations between antibody features (IgG subclass and antigen specificity) and effector function activities (antibody dependent cellular phagocytosis, cellular cytotoxicity, and cytokine release). We demonstrate via cross-validation that classification and regression approaches can effectively use the antibody features to robustly predict qualitative and quantitative functional outcomes. This integration of antibody feature and function data within a machine learning framework provides a new, objective approach to discovering and assessing multivariate immune correlates.

Antibody-dependent phagocytosis (ADP) is a potentially important immune mechanism to clear HIV. How HIV-specific ADP responses mature during HIV infection or in response to vaccinations administered, including the partially successful RV144 HIV vaccine, is not known. We established a modified ADP assay to measure internalisation of HIV antibody (Ab)-opsonised targets using a specific hybridisation internalisation probe. Labelled beads were coated with both biotinylated HIV gp140 envelope protein and a fluorescent internalisation probe, opsonised with Abs and incubated with a monocytic cell line. The fluorescence derived from the fluorescent internalisation probe on surface-bound beads, but not from internalised beads, was quenched by the addition of a complementary quencher probe. HIV Env-specific ADP was measured in 31 subjects during primary infection and early chronic HIV infection. Although ADP responses were present early during HIV infection, a significant increase in ADP responses in all 31 subjects studied was detected (P<0.001). However, when we tested 30 HIV-negative human subjects immunised with the Canarypox/gp120 vaccine regimen (subjects from the RV144 trial) we did not detect HIV-specific ADP activity. In conclusion, a modified assay was developed to measure HIV-specific ADP. Enhanced ADP responses early in the course of HIV infection were observed but no ADP activity was detected following the vaccinations administered in the RV144 trial. Improved vaccine regimens may be needed to capitalise on ADP-mediated immunity against HIV.

Antibody-dependent phagocytosis (ADP) is a potentially important immune mechanism to clear HIV. How HIV-specific ADP responses mature during HIV infection or in response to vaccinations administered, including the partially successful RV144 HIV vaccine, is not known. We established a modified ADP assay to measure internalisation of HIV antibody (Ab)-opsonised targets using a specific hybridisation internalisation probe. Labelled beads were coated with both biotinylated HIV gp140 envelope protein and a fluorescent internalisation probe, opsonised with Abs and incubated with a monocytic cell line. The fluorescence derived from the fluorescent internalisation probe on surface-bound beads, but not from internalised beads, was quenched by the addition of a complementary quencher probe. HIV Env-specific ADP was measured in 31 subjects during primary infection and early chronic HIV infection. Although ADP responses were present early during HIV infection, a significant increase in ADP responses in all 31 subjects studied was detected (P<0.001). However, when we tested 30 HIV-negative human subjects immunised with the Canarypox/gp120 vaccine regimen (subjects from the RV144 trial) we did not detect HIV-specific ADP activity. In conclusion, a modified assay was developed to measure HIV-specific ADP. Enhanced ADP responses early in the course of HIV infection were observed but no ADP activity was detected following the vaccinations administered in the RV144 trial. Improved vaccine regimens may be needed to capitalise on ADP-mediated immunity against HIV.

The HIV/AIDS pandemic continues to spread and an AIDS vaccine is urgently needed. Regional alliances and international collaborations can foster the development and evaluation of the next generation of AIDS vaccine candidates. The importance of coordinating and harmonizing efforts across regional alliances has become abundantly clear. We recently formed the AIDS Vaccine for Asia Network (AVAN) to help facilitate the development of a regional AIDS vaccine strategy that accelerates research and development of an AIDS vaccine through government advocacy, improved coordination, and harmonization of research; develops clinical trial and manufacturing capacity; supports ethical and regulatory frameworks; and ensures community participation.

No abstract available.

An effective HIV type 1 (HIV-1) vaccine will likely require elicitation of broadly reactive cell-mediated immune (CMI) responses against divergent HIV-1 clades. We compared anti-HIV-1 T-cell immune responses among 363 unvaccinated adults infected with diverse HIV-1 clades. Response rates to clade B Gag and/or clade B Nef in Botswana (95%) and Cameroon (98%) were similar when compared with those in countries previously studied, including Brazil (92%), Thailand (96%), South Africa (96%), Malawi (100%), and the United States (100%). Substantial cross-clade cell-mediated immune responses in Botswana and Cameroon confirm previous findings in a larger, more genetically diverse collection of HIV-1 samples. Copyright © 2006 by Lippincott Williams & Wilkins.

An effective HIV type 1 (HIV-1) vaccine will likely require elicitation of broadly reactive cell-mediated immune (CMI) responses against divergent HIV-1 clades. We compared anti-HIV-1 T-cell immune responses among 363 unvaccinated adults infected with diverse HIV-1 clades. Response rates to clade B Gag and/or clade B Nef in Botswana (95%) and Cameroon (98%) were similar when compared with those in countries previously studied, including Brazil (92%), Thailand (96%), South Africa (96%), Malawi (100%), and the United States (100%). Substantial cross-clade cell-mediated immune responses in Botswana and Cameroon confirm previous findings in a larger, more genetically diverse collection of HIV-1 samples. Copyright © 2006 by Lippincott Williams & Wilkins.