The Centers for Disease Control and Prevention (CDC) Influenza Division (ID) is responsible for developing Candidate Vaccine Viruses based on circulating and novel influenza strains. Candidate Vaccine Viruses (CVVs) are reassortant viruses that are used as the starting materials for seasonal and pandemic vaccines. To facilitate the development of the CVVs, CDC uses oligonucleotides and synthetic genes to transcribe the influenza genes to produce the CVVs.

During research on influenza CVVs, many different genes must be constructed, significantly more than is required in CVV production in most cases. The Influenza Division, therefore, requires bulk production of oligonucleotides with relaxed quality standards versus those required for actual CVV production. The sequences will still follow the natural evolution of viruses and, therefore, can still not be predicted.