Between the years of antigenic shifts, antigenic drifts
have happened almost annually and have resulted in outbreaks of variable extent and severity.
Although vaccine effectiveness was reduced this season because of antigenic drift
in H3N2 viruses, vaccination was still protective against vaccine-like influenza A (H3N2) viruses and influenza B viruses.
Our chances of having a perfect vaccine match during an outbreak may be low due to antigenic drift
, but if we have a vaccine that offers some protection in the face of an epidemic like the one in 1918-1919, significant amounts of morbidity and mortality could be averted.
Having such a process in place gives some assurance that researchers would be able to respond quickly to any antigenic drift
the H5 virus might experience, Dr.
Every few years, there is an antigenic drift
, which causes influenza epidemics.
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Similar to other viruses in the antigenic cluster, H3N2-[beta] A/swine/Texas/ A01104013/2012(H3N2) had a R189K mutation at the antibody-binding site of the hemagglutinin protein, which caused a recent antigenic drift
in subtype H3N2 IAVs (5,12).
One reason that it has been difficult to assess health risks associated with the influenza vaccine is that the vaccine's components can change from year to year in response to antigenic drift
In addition, continual antigenic drift
among influenza viruses frequently results in the circulation of new strains that may not be adequately covered by older vaccine.
This could be necessary if antigenic drift
reduces the effectiveness of the vaccine recently announced as being in development at GlaxoSmithKline (NYSE:GSK) or flu vaccines in the pipeline at French-based Sanofi Aventis (NYSE:SNY).
To assess the extent of antigenic drift
among recent human subtype H5N1 virus isolates relative to WHO-recommended candidate vaccine viruses, we performed hemagglutinin inhibition (HI) tests using ferret antisera raised against a panel of viruses, including A/Egypt/ N03072/2010 (the clade 2.
Unlike the injectable vaccine, protection provided by the nasal one appears to be commensurate with the other 3 years when an antigenic drift
from the vaccine strain was noted--about 85%, versus 30%-50% for the injectable.
, which occurs in viruses in all three groups, necessitates annual reformulation of the vaccine [6-8].
Given the mutations and antigenic drift
, because of which vaccines will always have limited effectiveness in control, new treatments such as ours, will be essential.