Birds and Mammals are the main reservoir of newly emerging
pandemic influenza viruses [1-3]. Global circulation of influenza A viruses in
avian species poses a constant threat to human public health. Vaccination
remains the main strategy against influenza. Over the last decade, the interest
in the live attenuated
cold-adapted reassortant influenza vaccine (LAIV) has increased
dramatically. To a large degree, it is because World Health Organization (WHO)
recognized the advantages of LAIV in the event of pandemic situation. For
instance, needle–free administration, high vaccine virus yield, easy down–
stream processing, cross–reactivity of immune responses etc. make LAIV very
attractive preparation in the face of pandemic situation.
Genetic stability and the absence of transmission potency
are the main properties of LAIVs, which guarantee their safety. Confirmation of
genetic and phenotypic stability is one of key points of characterisation of
LAIV, which is especially important in pandemic situation to guarantee its
safety profile during large–scale immunization campaigns.
In each of those studies,
38-40, 18-49 years old participants both sexes were randomly assigned to
receive two doses of vaccine or placebo at a 3:1 vaccine:placebo ratio. Vaccine
and placebo were administrated intranasally. The preclinical studies, as well
as safety
and immunogenicity of these three LAIVs for use in the pandemic situations
were earlier well documented and published. In this paper, we presented the
results of molecular genetics and virological studies conducted as a part of
phase I clinical trials. In particular, shedding, transmission and genetic
stability of H7N3, H5N2 and H2N2 LAIVs against pre–pandemic influenza viruses
were studied.
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