Vaccine
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Randomized Controlled Trial
Safety and immunogenicity of a virus-like particle pandemic influenza A (H1N1) 2009 vaccine in a blinded, randomized, placebo-controlled trial of adults in Mexico.
Virus-like particles (VLPs) can be rapidly developed from influenza virus genetic sequences in order to supply vaccine after the onset of a pandemic. The safety and immunogenicity of one or two doses of a recombinant A (H1N1) 2009 influenza VLP vaccine was evaluated in a two-stage, Phase 2, randomized, double-blind, placebo-controlled study conducted in 4563 healthy adults, 18-64 years of age, during the H1N1 2009 pandemic in Mexico. In Part A, 1013 subjects were randomized into four treatment groups (5 μg, 15 μg, or 45 μg hemagglutinin [HA] VLP vaccine or placebo) and vaccinated 21 days apart, with sera collected on Days 1, 14 and 36 for hemagglutination inhibition (HAI) testing. ⋯ The VLP vaccine groups demonstrated robust HAI immune responses after a single vaccination, with high rates of seroprotection (≥ 40 HAI titer) in 82-92% of all subjects and in 64-85% of subjects who were seronegative at the time of immunization. HAI geometric mean titers (GMTs), geometric mean ratios (GMRs) and seroconversion rates were also all statistically higher in the VLP groups compared to placebo for both post-baseline time points. Based on these data, additional clinical trials are in development to evaluate influenza vaccine candidate antigens manufactured using Spodoptera frugiperda (Sf9)/baculovirus-based VLP technology.
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Influenza is a significant cause of morbidity and mortality for pregnant women and infants worldwide. Influenza vaccination during pregnancy has been shown to be safe and highly effective and should be recommended for all pregnant women before the influenza season. ⋯ Obstacles to immunization include insufficient awareness of the disease burden and of the importance and safety of immunization, fear of liability and the wish to minimize interventions during pregnancy. Therefore, educational interventions for the public and health care workers are necessary to increase protection of pregnant women and young infants from influenza related complications.
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Accumulating evidence for the substantial burden of influenza in children has increased interest in the vaccination of young children against influenza. So far, however, few European countries have issued official recommendations to vaccinate healthy children, which is largely due to the popular belief that inactivated influenza vaccines are ineffective in young children. ⋯ The live attenuated influenza vaccine provides even greater effectiveness in children, but the overall potential of this vaccine is limited by its licensure for only children older than 2 years of age. The safety record of seasonal inactivated influenza vaccines is excellent even in the youngest children.
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During the 2009 influenza A (H1N1) pandemic several pandemic H1N1 vaccines were licensed using fast track procedures, with relatively limited data on the safety in children and adolescents. Different extensive safety monitoring efforts were put in place to ensure timely detection of adverse events following immunization. These combined efforts have generated large amounts of data on the safety of the different pandemic H1N1 vaccines, also in children and adolescents. ⋯ As a result, relatively little has been learned on the comparative safety of these pandemic H1N1 vaccines - particularly in children. It should be a collective effort to give added value to the enormous work going into the individual studies by adhering to available guidelines for the collection, analysis, and presentation of vaccine safety data in clinical studies and to guidance for the clinical investigation of medicinal products in the pediatric population. Importantly the pandemic has brought us the beginning of an infrastructure for collaborative vaccine safety studies in the EU, USA and globally.
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The aim of this study was to identify the common barriers and facilitators for acceptance of pandemic influenza vaccination across different countries. This study utilized a standardized, anonymous, self-completed questionnaire-based survey recording the demographics and professional practice, previous experience and perceived risk and severity of influenza, infection control practices, information of H1N1 vaccination, acceptance of the H1N1 vaccination and reasons of their choices and opinions on mandatory vaccination. Hospital-based doctors, nurses and allied healthcare workers in Hong Kong (HK), Singapore (SG) and Leicester, United Kingdom (UK) were recruited. ⋯ The acceptance of pandemic vaccine among healthcare workers was poor (13-41% of respondents). Breaking barriers to accept seasonal influenza vaccination should be part of the influenza pandemic preparedness plan. Mandatory vaccination even during pandemic is likely to arouse substantial discontent.