Science News from research organizations Scientists create universal nasal spray vaccine that protects against COVID, flu, and pneumonia A single nasal spray vaccine may one day shield us from viruses, pneumonia, and even allergies — all at once. Date: February 23, 2026 Source: Stanford Medicine Summary: Scientists at Stanford Medicine have unveiled a bold new kind of “universal” vaccine that could one day protect against everything from COVID-19 and the flu to bacterial pneumonia and even common allergens. Instead of targeting a specific virus or bacterium, the nasal spray vaccine supercharges the lungs’ own immune defenses, keeping them on high alert for months. In mice, it slashed viral levels, prevented severe illness, and even blocked allergic reactions. Share: Facebook Twitter Pinterest LinkedIN Email FULL STORY Researchers have created a nasal spray vaccine that protects mice against multiple viruses, bacteria, and even allergens for months. Credit: Shutterstock For decades, scientists have chased the idea of a universal vaccine capable of protecting against virtually any infectious threat. That goal has often seemed almost mythical. Now, researchers at Stanford Medicine and their collaborators report a major step toward that vision. In a new mouse study, they developed an experimental universal vaccine that shields against a broad range of respiratory viruses, bacteria, and even allergens. The vaccine is given intranasally -- such as through a nasal spray -- and provides wide ranging protection in the lungs that lasts for months. The findings, published Feb. 19 in Science , show that vaccinated mice were protected from SARS-CoV-2 and other coronaviruses, Staphylococcus aureus and Acinetobacter baumannii (common hospital-acquired infections), as well as house dust mites (a common allergen). According to senior author Bali Pulendran, PhD, the Violetta L. Horton Professor II and professor of microbiology and immunology, the level of protection across so many respiratory threats exceeded expectations. The study's lead author is Haibo Zhang, PhD, a postdoctoral scholar in Pulendran's lab. If similar results are achieved in people, a single vaccine could potentially replace multiple yearly shots for seasonal respiratory illnesses and provide rapid protection if a new pandemic virus emerges. Why Current Vaccines Need Updating This experimental vaccine works very differently from traditional vaccines. Since the late 1700s, when Edward Jenner introduced the term vaccination (from the Latin vacca for cow) after using cowpox to prevent smallpox, vaccines have relied on a common strategy known as antigen specificity. In simple terms, vaccines present the immune system with a recognizable piece of a pathogen -- such as the spike protein on SARS-CoV-2 -- so the body can quickly identify and attack the real virus later. "That's been the paradigm of vaccinology for the last 230 years," Pulendran said. The challenge is that many pathogens evolve quickly. When viruses change the structures on their surface, previously effective vaccines may lose potency. That is why updated COVID-19 boosters and annual flu shots are necessary. "It's becoming increasingly clear that many pathogens are able to quickly mutate. Like the proverbial leopard that changes its spots, a virus can change the antigens on its surface," Pulendran said. Most efforts to create broader vaccines have aimed to protect against an entire viral family, such as all coronaviruses or all influenza strains, by targeting viral components that mutate less frequently. The idea of one vaccine capable of defending against many unrelated pathogens has generally been viewed as unrealistic. "We were interested in this idea because it sounded a bit outrageous," Pulendran said. "I think nobody was seriously entertaining that something like this could ever be possible." A New Strategy That Activates Integrated Immunity Instead of copying part of a virus or bacterium, this new vaccine imitates the communication signals immune cells exchange during infection. By doing so, it links the body's two main defense systems -- innate and adaptive immunity -- into a coordinated and longer lasting response. Most existing vaccines primarily stimulate the adaptive immune system, which produces antibodies and specialized T cells that target specific pathogens and retain memory for years. The innate immune system responds within minutes of infection and acts more broadly, deploying cells such as dendritic cells, neutrophils and macrophages that attack perceived threats. However, innate immunity typically fades within days. Pulendran's team focused on the innate system's versatility. "What's remarkable about the innate system is that it can protect against a broad range of different microbes," Pulendran said. Although innate immunity is usually short lived, there have been hints that it can sometimes persist longer. One example is the Ba