Safety and Immunogenicity of a Prepandemic Influenza A (H5N1) Vaccine in Children
National Center for Immunology and Allergy, State Health Center, Martonhegyi ut 6, Budapest, Hungary. The Pediatric Infectious Disease Journal
(Impact Factor: 2.72).
11/2008; 27(12):1052-6. DOI: 10.1097/INF.0b013e3181861dd7
The avian influenza A (H5N1) virus is considered to be a potential cause of the next influenza pandemic. Children may be particularly vulnerable to the pandemic virus, and they may react differently than adults to vaccines. We report the results of the first clinical trial of an H5N1 vaccine in children.
Twelve healthy children (mean age +/- SD: 12.73 +/- 2.77 years) received a single dose of 6 microg of the inactivated whole virus vaccine Fluval. Twenty-one days after vaccination, immunogenicity was assessed by hemagglutination inhibition and microneutralization assays. Safety information was collected for 180 days.
No side-effects were observed, and the vaccine fulfilled all applicable U.S. and European immunogenicity criteria for licensure. The post/prevaccination geometric mean titer ratio was 16.95, the rate of seroconversion was 75% and the rate of seroprotection was also 75% 21 days after vaccination.
We confirmed our earlier findings of the present vaccine in adults showing encouraging safety and immunogenicity properties in children. Studies with the present vaccine in elderly subjects are underway.
Available from: mtakpa.hu
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ABSTRACT: Seasonal vaccination has been consistently shown to significantly reduce morbidity and mortality because of influenza epidemics, even in healthy, working adults. Here we report the results of the yearly licensing studies of the past 11 influenza seasons (1997-2007) with a trivalent, inactivated whole virus vaccine with an aluminum phosphate adjuvant system.
Sixty healthy volunteers per age group (18-60 years and 60 years and older) were enrolled to receive vaccination each year, thus, a total of 1080 subjects were studied. Serum antibody titers were measured by hemagglutination inhibition (HI).
The vaccine met the criteria for licensing each year, meaning seroprotection (achievement of an HI titer of >1:40 in >70% of subjects); seroconversion, i.e. a >4-fold increase in HI antibody titer, or reaching a titer of >1:40, in >40% of subjects; and an increase in geometric mean titers by >2.5-fold. Side effects were rare and mild. The same method was used to produce a pre-pandemic vaccine against influenza A (H5N1), which has been shown to be safe and immunogenic in humans.
We conclude that the method presented is safe, effective and may serve as a useful approach to seasonal and pandemic vaccine production even in less well-developed countries by means of technological transfer.
Available from: Geert Leroux-Roels
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ABSTRACT: H5N1 viruses are widely considered to be a probable cause of the next influenza pandemic. Influenza vaccines are considered to form the main prophylactic measure against pandemic influenza. The world's population is expected to have no pre-existing immunity against the pandemic virus strain and will need two vaccine doses to acquire protective immunity. A pandemic outbreak will spread much faster than it will take for pandemic vaccines to be produced and distributed. Therefore, increasing efforts are being made to develop prepandemic vaccines that can induce broad cross-protective responses and that can be administered as soon as a pandemic is declared or even before, in order to successfully prime the immune system and allow for a rapid and protective antibody response with one dose of the pandemic vaccine. Several vaccine manufacturers have developed candidate pandemic and prepandemic vaccines, predominantly based on reverse-genetics reference strains and have improved the immunogenicity by formulating these vaccines with different adjuvants. Clinical studies with inactivated split-virion or whole-virion vaccines based on H5N1 indicate that two immunizations appear necessary to elicit the level of immunity required to meet licensure criteria. A detailed overview is given of the most successful candidate vaccines developed by seven vaccine manufacturers.
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ABSTRACT: Influenza is a current infection with strong impact in public health care, but underdiagnosed in pediatrics, usually mistaked for other viral respiratory tract infections. Influenza is caused by ortomixovirus influenza A, B and C. A and B virus yeld year epidemics, and A virus, with an animal reservoir and ability to major antigenic changes, is responsible for world pandemics. A new world pandemic can be expected in the future, through the genetic evolution from the Asian aviar virus or swine influenza virus. In temperate climates influenza begins in autumn-winter, with an 8 weeks long epidemic season. Attack rates are more elevated in children, who are main agents for spread the disease to other risk groups. Outer proteins make virus able to spread and to make cell destruction. Inmunitary answer is strong but short in time. Influenza presents as a common cold with a sudden beginning, high fever and more systemic symptoms, but in infants and young children is difficult to differentiate influenza from other viral respiratory syndromes. Complications are frequent but usually not serious. Acute otitis media is the most frequent, but pneumonia is the first cause of hospitalization, specially in 5 years younger children. Reye síndrome is currently very rare. Diagnosis is clinically made in epidemic season. No complementary test is specific, instead rapid diagnosis tests, which are not usually avalaible in office pediatrics. Influenza can appear as a fever without apparent source in first stage. Risk groups year vaccination is the best way to reduce influenza morbility. Children with chronic diseases are classical receivers but today vaccination of children between 6 months and 18 years is also recommended. Influenza treatment is based on symptomatic relief. New specific neuraminidase inhibitors offer a modest benefit.
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