Stanford Researchers Develop Nasal Spray Vaccine with Broad Protection

Single spray could guard against flu, COVID-19, pneumonia and allergies, study finds

Published on Feb. 23, 2026

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Researchers at Stanford Medicine have developed an experimental nasal spray vaccine that has demonstrated immunity lasting for at least three months against multiple viruses, bacteria, and a common allergen in mice. The vaccine takes a fundamentally different approach from traditional antigen-specific vaccines, instead focusing on stimulating the innate immune system and prolonging its initial broad response.

Why it matters

A universal vaccine capable of protecting against a wide range of respiratory threats has long been a holy grail for public health. This nasal spray approach could represent a significant step forward, potentially reducing or eliminating the need for regular booster shots and offering broad protection against illnesses like COVID-19, flu, pneumonia and even allergies.

The details

The nasal spray vaccine is composed of three main elements: two molecules that stimulate macrophages and other immune cells in the lungs, and a third component that activates T lymphocytes of the adaptive immune system. By delivering the vaccine directly to the lungs via the nose, the researchers were able to maintain a localized immune state, keeping white blood cells and macrophages in a constant state of alert. After four doses, mice demonstrated immunity against coronaviruses, bacteria causing respiratory infections, and reduced sensitivity to house dust mites.

  • The study findings were unveiled by scientists at Stanford Medicine on February 23, 2026.
  • The protection observed in mice lasted for several months.

The players

Bali Pulendran

A specialist in immunology at Stanford University and co-author of the study.

Stanford Medicine

The university where the researchers developed the experimental nasal spray vaccine.

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What they’re saying

“The acquired immune system is much older from an evolutionary point of view. It is made up of macrophages, dendritic cells, neutrophils… All provide rapid and broad protection against different microbes. However, this immune response is generally very short: it fades after a few days, or even after three weeks maximum.”

— Bali Pulendran, Professor and Immunology Specialist

“It is crucial to go through the intranasal route. It allows us to directly target the airway immune system and results in strong, localized immunity. A result that could not have been obtained using a more conventional intramuscular injection.”

— Bali Pulendran, Professor and Immunology Specialist

What’s next

A full-scale clinical trial is now needed to assess the vaccine's safety and efficacy in humans.

The takeaway

This nasal spray vaccine represents a promising new approach to developing a universal vaccine capable of protecting against a wide range of respiratory threats, potentially reducing the need for regular booster shots and offering broad immunity against illnesses like COVID-19, flu, pneumonia and allergies.