Promising Intranasal Vaccine Shows Broad Immunity Against H5N1

Researchers at the University of Maryland School of Medicine have reported promising results from an early-phase clinical trial of an experimental intranasal influenza vaccine. This vaccine, designed to combat multiple strains of H5N1, showed potential in generating a broad immune response. The findings, published in Nature Communications, underscore the effectiveness of mucosal immunization strategies, which involve administering vaccines through the nostrils to enhance immune defenses against various influenza strains.

The study was led by Justin Ortiz, MD, MS, a Professor of Medicine at the University of Maryland School of Medicine (UMSOM) and a researcher at the Center for Vaccine Development and Global Health (CVD). “The spread of H5N1 influenza in animals with spillover into human populations globally highlights the critical need for effective countermeasures,” Ortiz stated. He emphasized that this intranasal vaccine could significantly contribute to pandemic preparedness by providing a practical and scalable solution to protect communities from evolving viral strains.

Current influenza vaccines are typically administered intramuscularly and primarily stimulate systemic immune responses. While they can effectively prevent symptomatic illness when well-matched to circulating strains, they may not adequately prevent transmission between individuals. In contrast, intranasal vaccines aim to stimulate immunity directly at the site of infection, offering a new approach to reduce the spread of the virus.

Trial Details and Findings

In this randomized, controlled trial, 40 healthy adult volunteers received varying doses of the H5 flu vaccine, which included the adjuvant BlueWillow’s NanoVax W 80 5EC. Participants in the control groups received either a placebo or a high dose of the H5 vaccine without the adjuvant. After six months, all volunteers received an intramuscular booster shot of the H5 flu vaccine.

The results indicated that the NanoVax H5 intranasal vaccine was safe and well tolerated by participants. Notably, only those who received the boosted nasal vaccine exhibited strong immune priming. This means their immune systems were effectively activated and prepared to respond when given a single dose of the intramuscular H5 flu shot. Even without the booster, the NanoVax H5 intranasal vaccine successfully triggered both mucosal and systemic immune defenses, an achievement not seen with other intranasal recombinant H5 flu vaccines in previous clinical trials.

Study co-lead author Meagan E. Deming, MD, Ph.D., an Assistant Professor of Medicine at UMSOM, pointed out that the vaccine helped the immune system recognize various versions of the H5N1 virus. This recognition is crucial, given the virus’s tendency to mutate over time. The use of the adjuvant may also allow for lower vaccine dosages, increasing the availability of current vaccine stocks during outbreaks.

The trial revealed that participants who received the adjuvanted H5 vaccine exhibited significant immune activity, including elevated levels of protective antibodies (IgG and IgA), increased memory immune cells, and a better capacity to kill infected cells. According to another co-lead author, Franklin R. Toapanta, MD, Ph.D., an Associate Professor of Medicine at UMSOM, these findings demonstrate effective mucosal priming and the potential for broad cross-clade immunity.

Implications for Public Health

The research aligns with global public health priorities aimed at developing vaccines that can reduce transmission and provide broader protection against emerging influenza strains. Mark T. Gladwin, MD, Dean of the University of Maryland School of Medicine, remarked on the importance of this research. He noted the necessity for further investigation into mucosal immune biomarkers and alternative immune correlates of protection, which could expedite the development of intranasal influenza vaccines.

The implications of this study are significant, as the need for effective influenza vaccines remains paramount in the ongoing fight against diseases with pandemic potential. The promising results of the NanoVax H5 intranasal vaccine may pave the way for innovative approaches to influenza prevention, ultimately benefiting global health initiatives.

For more detailed information, the study “An Intranasal Adjuvanted, Recombinant Influenza A/H5 Vaccine Primes Against Diverse H5N1 Clades: A Phase I Trial” can be found in the journal Nature Communications.