NCT06501963

Revealing Protective Immunity to Influenza Using Systems Immunology

• Status: Completed
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 51 (actual)
• Sponsor: Emory University · Academic / Other
• Sex: All
• Age: 18 Years – 49 Years
• Healthy volunteers: Accepted

Summary

The goals of this study are to better understand the human immune response to influenza vaccines, specifically the live attenuated (weakened) influenza vaccine given as a nasal spray. Better understanding why this vaccine does not work as well in adults as it does in children may help design better influenza vaccines.

Detailed description

Influenza (flu) viruses cause significant disease and death every year. Influenza vaccines protect against illness but their effectiveness can be limited. The influenza virus is notorious for its continuous mutation and potential to cause pandemics. This essentially creates a moving target for vaccine development, posing a significant challenge for global health. Current vaccines offer a certain degree of protection but are not fully effective due to the virus's ever-changing nature. In response to this, a live attenuated influenza vaccine (LAIV) was developed with the objective of providing a higher degree of protection. This type of vaccine has demonstrated remarkable effectiveness in children, surpassing the protection provided by inactivated flu vaccines. This made LAIV a preferred choice for administration to young children. However, when it comes to adults (individuals over 18 years of age), the scenario is markedly different. Recent studies have indicated a significant decline in LAIV's effectiveness in adults compared to children. Various clinical trials have reported that LAIV exhibits approximately 85% efficacy in children under the age of 18, which dramatically decreases to around 40%-60% in adults (aged 18-49 years). This suggests that adults do not respond as well to LAIV as children do. In adults, the LAIV-induced immunity appears to be short-lived, often lasting for only one influenza season, while in children LAIV has shown to provide long-lasting protection even against mismatched strains. Understanding the factors behind this discrepancy is critical to improve the protective efficacy of influenza vaccines across all age brackets. Unraveling this mystery could open the doors to the development of a superior flu vaccine, one that offers robust protection across all age groups. This study will enroll healthy adult (age 18-49) participants who have not received the influenza vaccine recently. Participants will be asked to come in for 3 visits over 1 month. Participants will receive the FDA-approved live attenuated influenza vaccine, given as a nasal spray. Study staff will collect baseline and follow-up biologic samples to compare how the immune system reacts. The biologic samples will be collected from the blood and nose to look at immune cells in these parts of the body.

Conditions

• Influenza

Interventions

Type	Name	Description
BIOLOGICAL	Live Attenuated Influenza Vaccine	The FDA-approved live attenuated seasonal influenza vaccine (LAIV) (FluMist®, AstraZeneca) is licensed in the US for people 2-49 years of age. The approved seasonal LAIV at the time of study enrollment will be obtained from the manufacturer. LAIV will be administered by a study nurse or health care provider at the Hope Clinic as a single 0.2 milliliter (mL) dose given as 0.1 mL spray in each nostril.

Timeline

• Start date: 2024-10-14
• Primary completion: 2025-04-01
• Completion: 2025-04-01
• First posted: 2024-07-15
• Last updated: 2026-03-30
• Results posted: 2026-03-30

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study