Stanford University researchers in the US are developing an experimental nasal spray designed to provide wide-ranging protection against respiratory illnesses, including common colds, flu, and dangerous bacterial infections. Unlike traditional vaccines, which target a specific pathogen, this “universal vaccine” primes the lungs’ immune cells to respond rapidly to almost any invading virus or bacterium. Animal studies have shown that the spray boosts lung macrophages, putting them on “amber alert,” and reduces viral infections by 100–1,000 times over three months. It also showed promise against antibiotic-resistant bacteria likeStaphylococcus aureusandAcinetobacter baumannii.

Experts caution that these results are preliminary, as human immune systems differ from mice, and keeping immune cells constantly alert carries potential risks of inflammation or tissue damage. Clinical trials are being planned to test both safety and effectiveness in humans. Researchers envision the spray as a complement to conventional vaccines rather than a replacement, potentially offering protection at the start of pandemic outbreaks or seasonal respiratory surges.

If human trials are successful, the once-a-season nasal spray could revolutionise respiratory disease prevention, providing temporary but broad protection to millions while pathogen-specific vaccines are developed. For now, the approach remains experimental, but it represents a dramatic shift in vaccine science and could pave the way for a new era of universal respiratory protection.