Universal Nasal Spray Vaccine Shows Promise Against Viruses, Bacteria & Allergies

For decades, the pursuit of a single vaccine capable of defending against a wide range of infectious threats has felt like a medical aspiration bordering on myth. Now, researchers at Stanford Medicine are reporting a significant step toward realizing that vision. A newly developed experimental vaccine, administered as a nasal spray, has demonstrated the ability to protect mice against a broad spectrum of respiratory viruses, bacteria, and even allergens. The findings, published February 19 in the journal Science, suggest a potential future where a single dose could replace multiple annual vaccinations and offer rapid protection against emerging pandemic viruses.

Beyond Antigen Specificity: A Modern Approach to Immunity

Traditional vaccines, tracing their origins back to Edward Jenner’s pioneering function with cowpox in the late 1700s, operate on the principle of antigen specificity. This means they introduce a component of a pathogen – like the spike protein of SARS-CoV-2 – to train the immune system to recognize and neutralize the real threat. However, this approach requires frequent updates as viruses and bacteria evolve, changing the antigens on their surfaces. Updated COVID-19 boosters and annual flu shots are prime examples of this ongoing adaptation. Stanford Medicine researchers are now exploring a different strategy.

The experimental vaccine developed by Bali Pulendran, PhD, and his team at Stanford, doesn’t mimic a specific pathogen. Instead, it focuses on activating the body’s innate immune system – a rapid, broad-spectrum defense mechanism that’s typically short-lived. The team’s work builds on earlier research clarifying how the Bacillus Calmette-Guerin (BCG) tuberculosis vaccine provides cross-protection against other infections in mice. They discovered that the BCG vaccine triggers both innate and adaptive immune responses, with the innate response sustained for months due to signals from T cells. This led them to hypothesize that a synthetic vaccine could replicate this effect.

Integrated Organ Immunity: Sustaining the Innate Response

The new formulation, currently known as GLA-3M-052-LS+OVA, is designed to stimulate this sustained innate immune response in the lungs. It combines toll-like receptor stimuli – which activate innate immune cells – with a harmless antigen, ovalbumin (OVA), an egg protein that attracts T cells to the lungs. These T cells then provide the signals necessary to keep the innate immune system “switched on” for weeks or even months. ScienceDaily reports that this sustained activation is key to the vaccine’s broad protective effects.

In the mouse study, vaccination involved administering droplets of the vaccine directly into the nostrils. Mice receiving three doses demonstrated robust protection against SARS-CoV-2 and other coronaviruses for at least three months. Unvaccinated mice exposed to the same viruses experienced significant weight loss, signs of severe illness, and often succumbed to infection. Their lungs showed extensive inflammation and high viral loads, while vaccinated mice exhibited minimal weight loss, survived infection, and had significantly lower viral levels in their lungs.

Broad Spectrum Protection: Viruses, Bacteria, and Allergens

The protective effects weren’t limited to viruses. Vaccinated mice were also shielded from bacterial respiratory pathogens, including Staphylococcus aureus and Acinetobacter baumannii, common causes of hospital-acquired infections. Encouraged by these results, the researchers expanded their investigation to include allergens. They exposed mice to a protein from house dust mites, a frequent trigger for allergic asthma. The Stanford Daily details how vaccinated mice showed a significantly weaker allergic response, with less mucus accumulation in their airways compared to unvaccinated mice.

“I think what we have is a universal vaccine against diverse respiratory threats,” stated Pulendran, highlighting the potential for a single intervention to address a wide range of respiratory illnesses.

How the Vaccine Works: A “Double Whammy” Effect

The vaccine’s effectiveness appears to stem from a “double whammy” effect. The sustained innate immune response dramatically reduces viral levels in the lungs – by as much as 700-fold in the study – creating a first line of defense. Any viruses that manage to bypass this initial barrier are then quickly confronted by a rapid adaptive immune response, triggered by the primed state of the lung’s immune system. Pulendran explained that this accelerated adaptive response can launch within just three days, compared to the typical two weeks required in unvaccinated mice.

What’s Next: From Mice to Humans

The next crucial step is human testing. Researchers are planning to initiate a Phase I safety trial to assess the vaccine’s tolerability in people. If the initial results are promising, larger studies will follow, potentially including controlled exposure to respiratory pathogens. Pulendran estimates that a two-dose nasal spray regimen could be sufficient for humans.

The timeline for potential availability is estimated at five to seven years, contingent on securing adequate funding and successful completion of clinical trials. The ultimate goal is a single, annual nasal spray that provides comprehensive protection against a multitude of respiratory threats, including COVID-19, influenza, respiratory syncytial virus (RSV), the common cold, bacterial pneumonia, and even seasonal allergens. Such a vaccine could fundamentally transform preventative healthcare and bolster global preparedness for future pandemics.

The research team included collaborators from Emory University School of Medicine, the University of North Carolina at Chapel Hill, Utah State University, and the University of Arizona. Funding for the study was provided by the National Institutes of Health, the Violetta L. Horton Professor endowment, the Soffer Fund endowment, and Open Philanthropy.