Is it more effective to put the vaccine in your nose than to get a shot?

A new study found that our noses are home to legions of long-lived immune cells that defend against viral and bacterial infections, and that they also run their own training centers to remember and respond to enemies. This was reported by the scientific journal Nature on the 31st of last month (local time) based on a paper by American researchers published in their journal.

This study is the most detailed investigation to date into the immune cells that make up the upper airway, the first line of defense for protecting the lungs. The results revealed that the upper airway, which consists of the nose, sinuses, mouth, and throat, serves as a key training ground for immune cells that ‘remember’ invading pathogens. This memory allows the immune cells to defend against similar microbes in the future.

The findings could help explain why mucosal vaccines administered through the nose or throat are more effective than regular vaccines injected into the muscle, and could speed up their development, immunologists said. Linda Wakim, an immunologist at the University of Melbourne in Australia who reviewed the paper, said the study clearly shows that even young adults and the elderly, whose immune systems are weaker, have an “arsenal of immune cells that can fight respiratory infections” in their upper airways.

Previous research on the immune system has focused primarily on immune cells in the blood and airways, which are relatively easy to access through blood draws and tissue biopsies, explains Sydney Ramirez, a researcher at the La Jolla Institute for Immunology in the US who led the study.

Then, with the advent of the COVID-19 pandemic, a viral variant emerged that replicated with high efficiency in the upper respiratory tract. The research team turned to nasopharyngeal swabs to find new ways to better understand how immune cells in the upper respiratory tract interact with pathogens and develop immune memory.

A nasopharyngeal swab is a swab that is inserted deep into the back of the nose when testing for COVID-19. It can reach the nasopharynx, the passage connecting the nasal cavity and the pharynx.

The researchers swabted about 30 healthy adults every month for more than a year to see how their immune cell populations changed over time. The swab samples contained millions of immune cells, including those that provide immune memory.

The researchers also discovered that they could use nasopharyngeal swabs to obtain tissue samples from hard-to-reach immune organs called adenoids, which are triangular-shaped lymphoid tissues located on the upper and posterior walls of the nasopharynx at the back of the nose.

Adenoids analyze the air you breathe. They also have a structure called a germinal center. Germinal centers, which are also found in other immune tissues, serve as training grounds for B cells that create antibodies that bind to foreign antigens and effectively form antibodies.

Adenoids shrink as adults, but the researchers found active germinal centers in the adenoids of study participants of all ages, “a reassuring result for all of us over the age of 20,” Ramirez said.

The researchers also stumbled upon evidence of this germinal center effect. During the study, several participants became infected with COVID-19. The researchers found that their nasal passages contained B cells that targeted SARS-CoV-2.

Germinal centers are usually activated only after acute infection or vaccination. But the researchers found germinal centers that were activated even when the participants did not report feeling sick. Donna Farber, an immunologist at Columbia University in the US who reviewed the paper, said the new swab technique could help researchers understand what activates germinal centers and how SARS-CoV-2 (the coronavirus) infection shapes this immune response.

He also said that these findings could provide a quantitative way to measure changes in immune responses after vaccination, especially for testing intranasal vaccine candidates. However, he also pointed out that there are still many challenges to be solved, as existing antibodies may block the protective effect of intranasal vaccines if the immune system is continuously activated in the upper respiratory tract.

The paper can be found at the following link (