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# FDA Works on Improved Vaccine Candidate
- URL: https://www.fdaweb.com/fda-works-on-improved-vaccine-candidate/
- Published: 2019-10-10T12:00:00.000Z
- Updated: 2026-09-15T01:55:41.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5145216

FDA says its scientists have developed two candidate vaccine viruses that may be used as the starting material for producing inactivated influenza vaccines. The candidate vaccine viruses protected lab animals against a highly pathogenic strain of Influenza A (H7N9), a potentially pandemic virus, an agency statement [says](https://www.fda.gov/vaccines-blood-biologics/influenza-candidate-vaccine-viruses-improved-amino-acid-substitution-hemagglutinin?ref=fdaweb.com). The candidates are influenza viruses that can be used commercially to produce vaccine to prevent influenza disease.

The agency says its scientists developed the candidate viruses by genetically modifying hemagglutinin, a viral protein that influenza virus uses to bind to cells that it infects. The study also demonstrated that the modification could facilitate large-scale production of the viruses in chicken eggs and animal cells through its effects on the activity of both hemagglutinin and neuraminidase, a second viral protein. The two proteins are located on the surface of influenza viruses and give influenza strains their main identity and form the basis of most influenza vaccines.

The FDA study was [reported](https://jvi.asm.org/content/93/19/e00570-19?ref=fdaweb.com) in the *Journal of Virology*.