Researchers at Stanford University in the US say they are developing a single nasal spray that could one day protect against a vast array of respiratory illnesses — from common colds and flu to dangerous bacterial infections — and may even reduce allergic reactions.
The experimental “universal vaccine,” tested so far only in animals, represents what the team describes as a dramatic shift from more than two centuries of vaccine science.
Instead of training the immune system to recognise a specific virus or bacterium, the spray prepares the lungs to respond instantly to almost any invading pathogen.
The findings, published in Science, have generated cautious excitement among experts, who describe the early results as promising but stress that human trials will be crucial.
Experts underlined that there are four types of influenza viruses—A, B, C and D. Influenza A and B viruses circulate and cause seasonal epidemics of disease.
In most countries, including India, immunisation with a flu shot is recommended for vulnerable population groups, including pregnant women, children aged six months to five years, people over 65, those with chronic medical conditions, and healthcare workers, on the lines of recommendations by the World Health Organisation (WHO).
There are other vaccinations available for respiratory viruses that cause flu-like symptoms that can turn severe in many people, including kids, the elderly and those with compromised immunity.
A RADICAL RETHINK OF IMMUNISATION
Traditional vaccines follow a model first introduced by Edward Jenner in the 18th century: expose the body to a harmless version or fragment of a pathogen so it learns to recognise and fight that specific threat.
Measles vaccines, for instance, protect against measles and COVID-19 vaccines protect against SARS CoV2. Each shot is tailored to a single enemy.
The Stanford team’s approach turns that model on its head. Rather than teaching the immune system to recognise one invader, the nasal spray mimics the chemical signals immune cells use to communicate during an infection.
When administered through the nose, the treatment leaves key immune cells in the lungs — known as macrophages — in a heightened state of readiness. Researchers describe it as putting these cells on “amber alert.”
In animal studies, this boosted state lasted about three months. During that time, viruses attempting to infect the lungs were reduced by between 100- and 1,000-fold. Even when pathogens managed to slip past the first line of defence, the rest of the immune system responded with striking speed.
Beyond viruses, the spray also protects against two significant bacterial threats: Staphylococcus aureus and Acinetobacter baumannii, both of which can cause severe lung infections and are increasingly resistant to antibiotics.
PROMISE — AND UNANSWERED QUESTIONS
Despite the enthusiasm, researchers are clear that the work remains in its earliest stages. So far, the experiments have been conducted in mice, whose immune systems differ in important ways from those of humans.
“People’s immune responses are shaped by decades of exposure to infections, vaccines and environmental factors, making outcomes harder to predict,” an immunologist with the Indian Council of Medical Research (ICMR) told India Today.
To test whether the same broad protection can be achieved in humans, the researchers are now planning tightly controlled clinical trials, said the scientist.
In one proposed study, volunteers would receive the spray and then be deliberately exposed to a virus to measure how effectively their bodies respond.
There are also safety considerations. Keeping the immune system on constant alert could carry risks. An overactive immune response may damage healthy tissue or trigger inflammatory disorders.
The ICMR scientist said at this stage, the findings look promising but cautioned that researchers must ensure the approach does not lead to an overactive immune system which can cause unintended harm.
Researchers concede that the spray is unlikely to replace conventional vaccines. Instead, they envision it as a complementary tool.
In the early stages of a pandemic — as seen in 2020 during the emergence of COVID19, for instance— such a broad-acting spray could buy valuable time, reducing severe illness and deaths while scientists develop a pathogen-specific vaccine.
Another potential use could be seasonal. At the start of winter, when multiple respiratory viruses begin circulating, a preventive spray might provide temporary, wide-ranging protection against the usual surge of coughs, colds and flu.
For now, the concept remains experimental. But if human trials confirm what animal studies suggest, the idea of a once-a-season nasal spray shielding millions from a host of respiratory threats may move from bold theory to medical reality.
