Vaccine
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Randomized Controlled Trial
A nasally administered trivalent inactivated influenza vaccine is well tolerated, stimulates both mucosal and systemic immunity, and potentially protects against influenza illness.
A randomized placebo-controlled double-blind trial of a nasally administered inactivated trivalent influenza vaccine formulated with partially purified meningococcal outer membrane proteins (OMP-TIV) was conducted in 1349 healthy adults aged 18-64 years. Subjects received either vaccine containing 15 μg of haemagglutinin (HA) of each of three influenza strains for the 2003-2004 season on days 0 and 14, or 30 μg on day 0 and saline placebo on day 14, or placebo on days 0 and 14. Vaccination was well tolerated, with similar reactogenicity as placebo. ⋯ In participants receiving all doses of either vaccine regimen the incidence of culture-confirmed influenza with respiratory symptoms and with or without fever was 0.77% (7/904) vs. 2.03% (9/443) in placebo recipients (p=0.045, Fisher's exact test; relative risk reduction 62%), despite circulation of a drift variant A/H3N2 that was poorly matched to vaccine. An OMP-TIV vaccine was well tolerated and reduced risk of symptomatic culture confirmed influenza. Vaccine efficacy will need to be validated in a season with a higher attack rate.
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Estimates of influenza vaccine effectiveness from observational studies that rely on physician-ordered influenza tests may be biased if physician testing behavior is influenced by patient vaccination status. To assess the potential for differential diagnostic testing of children by vaccine status, we examined the association between receipt of a commercial influenza diagnostic test and influenza vaccination among children aged 6-59 months who sought care at the Marshfield Clinic for acute respiratory or febrile illnesses during the 2004-05 through 2007-08 influenza seasons. There was no significant association between prior influenza vaccination and receipt of a diagnostic test for influenza. These findings suggest that estimates of vaccine effectiveness derived from observational studies among children are unlikely to be biased due to differential diagnostic testing.
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Comparative Study
The effectiveness of trivalent inactivated influenza vaccine in children over six consecutive influenza seasons.
To estimate the effectiveness of two doses of trivalent inactivated influenza vaccine (TIV) over six consecutive influenza seasons in a small community in Japan. ⋯ Vaccination with two doses of TIV was consistently effective in preventing influenza-associated clinic visits and hospitalizations.
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Comparative Study
The development of vaccine viruses against pandemic A(H1N1) influenza.
Wild type human influenza viruses do not usually grow well in embryonated hens' eggs, the substrate of choice for the production of inactivated influenza vaccine, and vaccine viruses need to be developed specifically for this purpose. In the event of a pandemic of influenza, vaccine viruses need to be created with utmost speed. ⋯ Two approaches were followed, the classical reassortment approach and the more recent reverse genetics approach. This report describes the development and the characteristics of current pandemic H1N1 candidate vaccine viruses.
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Due to the advent of the new influenza A (H1N1) strain in 2009, many countries introduced mass immunization programs. Healthcare workers (HCWs) were amongst the key groups targeted for the vaccine in these programs. However, experience with the seasonal influenza vaccine has shown that there are multiple barriers related to the attitudes and perceptions of the population which influence uptake. ⋯ While studies reported high rates of willingness to receive the vaccine, in reality these did not transpire. Aside from promoting seasonal flu vaccination, authorities need to start educational campaigns much earlier in a pandemic. Programs that are simultaneously launched with the introduction of the vaccine will not be as successful, as those which have built momentum alongside the pandemic.