An experimental, intranasal influenza vaccine developed by Emergent Biosolutions, Inc. passed a years-long test this week, showcasing strong immune responses among a small group of volunteers in a phase one study.
The results, published in the Journal of Clinical Investigation, showed that after a single dose of the vaccine, intranasal recipients shed viral DNA for two to four weeks and displayed high levels of serum neutralizing antibodies at 26 weeks post vaccination. That level proved unchanged three to five years later.
Among participants, all 18 to 49 years old, the vaccine was administered intranasally to 28, orally to 10, and through a tonsillar swab to 25. Tonsillar recipients displayed similar antibody responses to those that received it intranasally. However, recipients of the intranasal version also gained mucosal antibody responses in the nose, mouth, and rectum, granting its recipients a means of limiting transmission of mucosal tissue infecting viruses as well.
In their analysis, the study authors proposed that the recombinant, replicating adenovirus vaccine may have an advantage over other types of vaccines due to its ability to express viral proteins at higher levels for longer. They expanded this speculation to include all replication-competent vector vaccines.
The vaccine works by spurring antibodies to the protein hemagglutinin, a surface portion of influenza viruses that attaches to human cells. The study authors concluded that it could also be adapted for use against other viruses such as HIV or SARS-CoV-2.