May 9, 2022 — Scientists are working on COVID vaccines delivered by nasal sprays that could prevent the coronavirus from invading the body at its most common entry point, the mucous membrane of the nose and throat.
More than a dozen clinical trials with nasal sprays are underway, The Guardian reported.
USA today said Vietnam, Thailand, Brazil and Mexico have already started manufacturing the nasal vaccine in anticipation of successful clinical trials.
A nasal vaccine would likely be used as a booster in the United States, but could be widely used in less developed parts of the world where injectable vaccines are not common, USA today reported.
While injection vaccines help the body prevent serious illnesses, nasal vaccines could prevent the virus from entering the body in the first place. The effectiveness of injectable vaccines declines over time and COVID variants can evade vaccines, as evidenced by the high number of Omicron cases.
“If you think of your body as a castle, an intramuscular vaccination really protects the interior areas of your castle, so once invaders come in, that immunity protects against their taking the throne,” Sean Liu, MD, medical director of the Covid clinic the testing unit at the Icahn School of Medicine at Mount Sinai in New York, said The Guardian.
“But if you train your immune system to work at the gates of the castle, invaders not only have a hard time getting in, they may have a hard time spreading inside.”
A nasal vaccine could be more easily manufactured and distributed because it is stored in a regular refrigerator rather than at ultra-cold temperatures like Moderna and Pfizer mRNA vaccines. People who don’t like needles might accept a nasal vaccine.
And it would be much cheaper to produce, USA today mentioned. Peter Palese, who also works on nasal vaccines at the Ichan School of Medicine, said a nasal dose could be produced for around 30 cents versus $30 for a Moderna or Pfizer dose.
Scientists face many challenges in their research, including measuring the strength of the immune response to the nasal vaccine.
Different techniques are used to develop the nasal spray. At Ichan School of Medicine, they make the vaccine in eggs, like flu shots. Cincinnati Children’s Hospital in Ohio tries canine flu, USA today mentioned. A nasal version of the Oxford/AstraZeneca vaccine is based on a weakened adenovirus, The Guardian reported.
In January 2021, researchers from Lancaster University in England and the Texas Biomedical Research Institute in San Antonio reported that rodents given two doses of a nasal vaccine had antibody and T-cell responses strong enough to suppress SARS-CoV-2.