Centers for Disease Control and Prevention (CDC) performs genome sequencing to compare the genetic sequences of vaccine viruses with those of circulating viruses. This is one way to assess how closely related the circulating influenza viruses are to the viruses the influenza vaccine is formulated to protect against.
CDC uses “Next Generation Sequencing” (NGS) methodologies that provide a tremendous amount of detail about each influenza genome. NGS techniques represent various high-throughput DNA sequencing strategies, whereby, millions to billions of DNA strands are sequenced in a highly parallel manner, dramatically improving throughput to understand sample complexity. This level of detail benefits decision-making with regard to vaccine composition, because it can help identify emerging changes in circulating flu viruses much earlier than before.
To sequence influenza genomes, viral RNA must be isolated, then amplified to have enough material to analyze. Once amplified, it is run on a fragment analyzer to assess quality. Here, a scientist runs a plate through a fragment analyzer.
Influenza (flu) viruses change constantly. As a WHO Collaborating Center for Influenza (WHO CC) and the U.S. National Influenza Center, CDC monitors flu activity nationally and globally with other labs, looking for changes in circulating viruses. CDC monitors flu viruses because changes can impact the effectiveness of flu vaccine. When circulating viruses are substantially different from those in the vaccine, vaccine effectiveness can be reduced. If it looks like viruses are starting to change in specific ways (which can impact how well the vaccine works), this can trigger health authorities to recommend different viruses for vaccine production.
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