Are We Close to a Universal Vaccine for Respiratory Illnesses?

Vaccines generally protect you against a single, specific disease. They give the immune system an idea of ​​what this invader looks like, so your cells are ready to take action.

Some, however, do something a little different.

For example, researchers noticed during the pandemic that people who received the BCG tuberculosis vaccine — which is not recommended in the United States but is commonly used in countries where the disease is endemic — had additional protection against COVID-19. This is consistent with decades of observations that the vaccine prevents a handful of other diseases. Although the vaccine itself has a mixed success rate, how it works has piqued scientists’ interest: BCG turns out to stimulate the innate immune system, which is not specific to any given pathogen, and provides broad, albeit low-level, protection against many different infections.

So could there be a way to create a more comprehensive vaccine, one that would protect against many viruses and bacteria simultaneously? In a new article in Scienceresearchers describe a vaccine, administered in four doses of nasal spray, that prevented mice from being infected with influenza, COVID-19, SARS and a bacteria that causes respiratory infections. The results will need to be confirmed and the vaccine approach tested in other animals, including humans, before its true significance is clear. But the study provides a tantalizing glimpse into a fundamentally different and far-reaching way to prevent disease.

A curious mix of ingredients

The goal was to stimulate immune pathways similar to those triggered by BCG, without including live bacteria, as required for this particular vaccine, says Bali Pulendran, professor of microbiology and immunology at Stanford University and author of the new study. Thus, the new vaccine contains a cocktail of substances intended to stimulate several aspects of the immune system.

When researchers gave the treatment to mice for four weeks and then exposed them to pathogens, what they saw was promising. “One month after vaccination, three months after vaccination, and in some cases up to six months after vaccination, the mice were protected against SARS-CoV-2, the original SARS pathogen, and another coronavirus,” as well as other pathogens, says Pulendran. Exploring further, they found that the vaccine had induced the formation of tiny immune structures in the lungs, fortresses from which the mouse’s body could continually fight off infection.

These structures appear to be essential, says Akiko Iwasaki, a professor of immunology at the Yale School of Medicine, who was not involved in the study but calls it “very interesting.”

“In humans, there are different structures in the nose, throat and deeper lungs,” she says. “Whether or not this type of vaccination can induce similar structures in humans needs to be tested.”

Additional work is needed

Indeed, the next step to take advantage of these results will be to conduct more in-depth testing, says Pulendran. Humans and mice, although they have similarities, are different in many ways, which could derail efforts to bring this approach closer to application. A vaccine capable of simultaneously protecting against many diseases is still far from being available.

But this research is an interesting step in that direction, says Ellen Foxman, a professor of immunology at the Yale School of Medicine who was not involved in the study. “It’s a really exciting idea. And in my opinion, it’s also a trending idea in immunology,” she says, noting that BCG’s effects during the pandemic have led many researchers to think about how to produce broad protection with new types of vaccines. While this study may be among the first to examine this relationship, she expects to see more work along these lines in the years to come.