All content matching "vaccine"

Genotype-specific features reduce the susceptibility of South American yellow fever virus strains to vaccine-induced antibodies

The resurgence of yellow fever in South America has prompted vaccination against the etiologic agent, yellow fever virus (YFV). Current vaccines are based on a live-attenuated YF-17D virus derived from a virulent African isolate. The capacity of these vaccines to induce neutralizing antibodies against the vaccine strain is used as a surrogate for protection. However, the sensitivity of genetically distinct South American strains to vaccine-induced antibodies is unknown. We show that antiviral potency of the polyclonal antibody response in vaccinees is attenuated against an emergent Brazilian strain. This reduction was attributable to amino acid changes at two sites in central domain II of the glycoprotein E, including multiple changes at the domain I–domain II hinge, which are unique to and shared among most South American YFV strains. Our findings call for a reevaluation of current approaches to YFV immunological surveillance in South America and suggest approaches for updating vaccines.

Reduced neutralization of SARS-CoV-2 B.1.617 by vaccine and convalescent serum

SARS-CoV-2 has undergone progressive change with variants conferring advantage rapidly becoming dominant lineages e.g. B.1.617. With apparent increased transmissibility variant B.1.617.2 has contributed to the current wave of infection ravaging the Indian subcontinent and has been designated a variant of concern in the UK. 

Effectiveness of COVID-19 vaccines against hospital admission with the Delta (B.1.617.2) variant

We recently reported vaccine effectiveness (VE) estimates against symptomatic disease with the Delta (B.1.617.2) variant.(1) After a full course, VE reached 88% with the Pfizer/BioNTech BNT162b2 vaccine and 67% with the AstraZeneca ChAdOx1 AZD1222 vaccine. This provided important evidence that despite modest reductions in protection, vaccines remain effective against Delta. However, the very recent emergence of the variant and the relatively low case numbers meant that it was not possible to estimate VE against severe disease.

CEPI (DRAFT NOT FOR DISTRIBUTION) position on immunepathology associated with SARS-CoV-2

DRAFT v0.8 (Mar 03, 2020)Possible Enhanced Disease in Vaccinees Following Exposure to Live Virus: Considerations for Preclinical Studies and Early Clinical Trials in the Context of Developing a COVID-19 Vaccine

A new class of broadly neutralizing antibodies that target the glycan loop of Zika virus envelope protein

Results showed in this article have strong implications for developing anti-ZIKV vaccines and therapeutic mAbs.

A yellow fever–Zika chimeric virus vaccine candidate protects against Zika infection and congenital malformations in mice

The authors of this study report the engineering of a chimeric virus vaccine candidate (YF-ZIKprM/E) by replacing the antigenic surface glycoproteins and the capsid anchor of YFV-17D with those of a prototypic Asian lineage ZIKV isolate.

4 EU-funded Zika consortia met in Marseille during the International Symposium to discuss a common strategy for vaccine development

Successful technology transfer of a Zika vaccine developed by Institut Pasteur Shanghai-Chinese Academy of Sciences (IPS-CAS) to Chongqing Zhifei Biological Products Co., Ltd.

Institut Pasteur Shanghai-Chinese Academy of Sciences (IPS-CAS), a partner of the ZIKAlliance consortium, announced that it has entered into a collaborative research agreement with Chongqing Zhifei Biological Products Stock Co., Ltd. (Zhifei) for the clinical studies and commercialization of a recombinant Zika virus subunit vaccine developed by IPS-CAS.

Projected Impact of Dengue Vaccination in Yucatán, Mexico

Analysis of potential dengue vaccine impact in Yucatán Mexico.

Clinical efficacy and safety of a novel tetravalent dengue vaccine in healthy children in Asia

A phase 3, randomised, observer-masked, placebo-controlled trial of a new tetravalent vaccine against dengue fever. Abstract Background: An estimated 100 million people have symptomatic dengue infection every year. This is the first report of a phase 3 vaccine efficacy trial of a candidate dengue vaccine. We aimed to assess the efficacy of the CYD dengue vaccine against symptomatic, virologically confirmed dengue in children. Methods: We did an observer-masked, randomised controlled, multicentre, phase 3 trial in five countries in the Asia-Pacific region. Between June 3, and Dec 1, 2011, healthy children aged 2—14 years were randomly assigned (2:1), by computer-generated permuted blocks of six with an interactive voice or web response system, to receive three injections of a recombinant, live, attenuated, tetravalent dengue vaccine (CYD-TDV), or placebo, at months 0, 6, and 12. Randomisation was stratified by age and site. Participants were followed up until month 25. Trial staff responsible for the preparation and administration of injections were unmasked to group allocation, but were not included in the follow-up of the participants; allocation was concealed from the study sponsor, investigators, and parents and guardians. Our primary objective was to assess protective efficacy against symptomatic, virologically confirmed dengue, irrespective of disease severity or serotype, that took place more than 28 days after the third injection. The primary endpoint was for the lower bound of the 95% CI of vaccine efficacy to be greater than 25%. Analysis was by intention to treat and per procotol. This trial is registered with ClinicalTrials.gov, number NCT01373281. Findings: We randomly assigned 10 275 children to receive either vaccine (n=6851) or placebo (n=3424), of whom 6710 (98%) and 3350 (98%), respectively, were included in the primary analysis. 250 cases of virologically confirmed dengue took place more than 28 days after the third injection (117 [47%] in the vaccine group and 133 [53%] in the control group). The primary endpoint was achieved with 56·5% (95% CI 43·8—66·4) efficacy. We recorded 647 serious adverse events (402 [62%] in the vaccine group and 245 [38%] in the control group). 54 (1%) children in the vaccine group and 33 (1%) of those in the control group had serious adverse events that happened within 28 days of vaccination. Serious adverse events were consistent with medical disorders in this age group and were mainly infections and injuries. Interpretation: Our findings show that dengue vaccine is efficacious when given as three injections at months 0, 6, and 12 to children aged 2—14 years in endemic areas in Asia, and has a good safety profile. Vaccination could reduce the incidence of symptomatic infection and hospital admission and has the potential to provide an important public health benefit.

Decline in Diarrhea Mortality and Admissions after Routine Childhood Rotavirus Immunization in Brazil: A Time-Series Analysis

In 2006, Brazil began routine immunization of infants <15 wk of age with a single-strain rotavirus vaccine. The authors in this paper evaluated whether the rotavirus vaccination program was associated with declines in childhood diarrhea deaths and hospital admissions by monitoring disease trends before and after vaccine introduction in all five regions of Brazil with varying disease burden and distinct socioeconomic and health indicators.