New Hope for Oral Flu Vaccine as Prime Season Descends

A new study shows that there might be a way to protect against influenza infection without needing to stir up antibody response.

Scientists from Stanford University investigated the effectiveness of an oral tablet flu vaccine called VXA-A1.1 by Vaxart, which uses cellular correlates of protection. Results from the Phase II human influenza challenge trial showed that those who were given VXA-A1.1 were better at providing protection against viral shedding compared to the injected inactivated influenza vaccine (IIV).

The 141 participants were divided into three groups who received either VXA-A1.1, an injected quadrivalent IIV, or a placebo and were challenged with the H1N1 flu virus 90 to 120 days post-vaccination. The researchers used mass cytometry to assess over 40 different immune cell parameters in collected blood samples. Profiling was conducted on the day before the vaccine was administered and then seven days after.

Those who received VXA-A1.1 were found with plasmablasts and hemagglutinin (HA+)-specific cells that contributed to protection from viral shedding after 90 days. This was not seen in those who got IIV or a placebo. On day 8, those who were given the oral drug demonstrated T cell expressing markers that suggested enhanced mucosal tissue homing.

“The data show that cellular responses are potentially more relevant for protection for an oral vaccine than circulating antibody responses,” said Dr. David McIlwain, a senior research scientist from the Stanford School of Medicine and the study’s lead author, in a statement.

This is the first study to indicate that VXA-A1.1 may be viable against the influenza vaccine, providing a ray of hope to those looking for less invasive preventive solutions.

Influenza remains a leading cause of death in the U.S. According to the Centers for Disease Control and Prevention (CDC), around 36,000 people have died from the flu over the last decade. The highest numbers were recorded from 2017 to 2018 (at 61,000). From 2019 to 2020, around 22,000 flu-related deaths were logged in the U.S. alone. Worldwide, flu deaths range from 300,000 to 600,000 per year.

Vaxart is a clinical-stage biotechnology firm that focuses on developing oral vaccine solutions against a number of viruses, including norovirus, coronavirus, respiratory syncytial virus (RSV), seasonal flu, and the human papillomavirus (HPV). In September, the company announced a new Manufacturing and Quality Advisory Board comprised of high-profile scientists with vast drug development backgrounds as part of plans to advance the late-stage development and commercialization of its growing vaccine portfolio. In August, it formed a Scientific and Clinical Advisory Board to act as adviser to Vaxart as it develops new technology.

Details of the VXA-A1.1 study are published in Cell Host and Microbe.