Stanford's Universal Nasal Spray Vaccine Protects Against COVID, Flu, and Pneumonia in One Shot

For 230 years, vaccines have worked by showing the immune system a specific piece of a specific pathogen. It's effective, but it has a fundamental weakness: when viruses mutate, the vaccine stops working. That's why we need new flu shots every year and updated COVID boosters every few months. Now, researchers at Stanford Medicine have built something radically different. In a study published February 19, 2026 in the journal Science, a team led by Bali Pulendran, PhD, the Violetta L. Horton Professor II and professor of microbiology and immunology, has developed an experimental universal vaccine delivered as a nasal spray that protects against a remarkably broad range of respiratory threats — not by targeting specific pathogens, but by supercharging the lungs' own frontline defences. In mouse studies, the nasal vaccine protected against SARS-CoV-2 and other coronaviruses, Staphylococcus aureus and Acinetobacter baumannii (common hospital-acquired bacterial infections), and even house dust mites (a major allergen). The protection lasted for months after a single administration. 'The level of protection across so many respiratory threats exceeded our expectations,' said Pulendran. The key innovation is that this vaccine doesn't rely on 'antigen specificity' — the traditional approach of training the immune system to recognise one particular virus. Instead, it activates innate immune cells already stationed in the lungs, essentially putting them on high alert against any invader. Think of traditional vaccines as teaching your immune system to recognise a specific criminal's face. This new approach is more like installing a state-of-the-art security system that detects any intruder, regardless of what they look like. The implications are enormous. Respiratory infections kill more than 4 million people worldwide every year. A single nasal spray that could protect against COVID, flu, pneumonia, and other lung infections would be transformative — especially in developing countries where access to multiple vaccines is limited. If similar results are achieved in humans, a single spray could potentially replace multiple yearly shots and provide rapid protection if a new pandemic virus emerges. The study's lead author, Haibo Zhang, PhD, a postdoctoral scholar in Pulendran's lab, noted that the nasal delivery route is crucial: by targeting the lungs directly, the vaccine establishes protection exactly where respiratory pathogens attack. Human clinical trials are being planned. In the meantime, this research represents a fundamental shift in how we think about vaccination — from chasing individual viruses to fortifying the body's own defences against all of them at once. The era of pathogen-agnostic vaccines may be closer than anyone thought.