The viral load in vaccinated animals dropped by a factor of 700, and the time to targeted immune response shortened from two weeks to three days: With these results, a team at Stanford Medicine published their vaccine approach in Science on February 19, 2026, demonstrating that the nasal spray protected mice for three months against six pathogens and allergens simultaneously. The spray does not target a specific disease-causing agent but puts the lungs into continuous defensive readiness.
What is this actually?
The human immune system consists of two arms with different response times. The first, the innate immune system, responds within minutes to general danger signals without knowing which pathogen it is fighting. The second, the adaptive immune system, is more specific: it produces custom-made antibodies but takes one to two weeks to do so. Conventional vaccines train the adaptive system.
The Stanford team led by Bali Pulendran, professor of immunology at Stanford Medicine and director of the Institute for Immunity, Transplantation and Infection, took a different approach. Their formulation contains signaling molecules that activate so-called toll-like receptors on immune cells in the lungs. These receptors are the alarm sensors of the innate immune system. At the same time, T cells are attracted to the lungs, where they release messenger substances and extend the state of heightened vigilance. Normally, the innate response subsides after a few days. In the animal experiments, it lasted at least three months.
The difference from conventional vaccines: the spray does not target the surface of a specific pathogen. It puts the lungs in general alert status that works against any invader, whether virus, bacterium, or allergen.
Why now?
The search for a universal vaccine against respiratory diseases is not a new endeavor. Flu vaccines must be reformulated each year because influenza viruses mutate and existing antibodies no longer recognize the altered variants. If the seasonal forecast is off, effectiveness can drop sharply. In the 2014/15 flu season in the United States, the Centers for Disease Control and Prevention estimated the effectiveness of that year's vaccine at just 19 percent because a dominant H3N2 strain was not included in the formula.
COVID-19 demonstrated the same fundamental problem on a larger scale. The mRNA vaccines from BioNTech/Pfizer and Moderna were developed in record time and initially provided good protection against severe disease. Then new variants appeared, boosters became necessary. They did not protect against influenza.
Pulendran's concept bypasses the problem because it does not target the antigen of a specific pathogen but instead increases the general defensive capability of the lungs.
Comparison with previous approaches
Vaccines that act on the innate immune system already exist. The approved herpes zoster vaccine Shingrix contains the adjuvant complex AS01B, which works via similar toll-like pathways and raises protection rates to over 90 percent. AS01B enhances a response to varicella-zoster antigen that is pathogen-specific. The Stanford approach aims to protect without pathogen-specific antigen.
The concept of nasal administration is also not new. CanSino Biologics from China developed Convidecia Air, an inhalable COVID-19 vaccine licensed in China as a booster in 2022. It still targets specifically the spike protein of SARS-CoV-2. The Stanford spray attempts to combine both: nasally administered and pathogen-neutral in its protective effect.
In animal experiments, a single spray protected mice for at least three months against six threats: SARS-CoV-2 and other coronaviruses, influenza viruses, Staphylococcus aureus, Acinetobacter baumannii, and dust mites. The team estimates that two doses might suffice in humans.
What does this mean in practice?
The most important caveat: all results come from mouse experiments. In vaccine research, such animal experiments frequently do not produce comparable results in humans. The mouse immune system differs in several relevant aspects from the human system. Pulendran's team emphasizes that safety and efficacy in humans must still be demonstrated, first in safety studies, then in controlled exposure studies with volunteers.
If the vaccine passes clinical trials, it would have practical advantages over today's vaccination routine. No physician needs to administer an injection. People who fear needles or lack easy access to medical practices would be within reach. An annual flu vaccination could be replaced by a pathogen-neutral spray that simultaneously protects against COVID-19 and bacterial pneumonia.
18 million dollars for the next step
In June 2026, ARIA, the British Advanced Research and Invention Agency, awarded Pulendran's team approximately 18 million dollars over four and a half years. ARIA was founded in 2023 following the model of the U.S. Defense Advanced Research Projects Agency (DARPA). The funding program is called Sustained Viral Resilience and aims at a new class of medicines: sustained innate immune prophylactics defined by the target organ, not the pathogen.
Pulendran estimates that a clinically deployable product is possible with adequate funding within five to seven years, thus earliest by 2031. By then, regulatory bodies must decide how to classify a vaccine that does not target a specific pathogen. For classical approval procedures, which are always oriented toward a specific pathogen, this would represent a new examination format.