Nasal vaccine shows potential to stop COVID-19 before it starts

Scientists at the Washington University School of Medicine (WashUMed) have developed a new COVID-19 vaccine that is administered through the nose. Using a mouse model, the team demonstrated that a single dose of the nasal vaccine successfully blocked COVID-19 infection. Next, the researchers will test the safety and efficacy of the vaccine in nonhuman primates and humans.

A growing collection of research suggests that the nose is often the initial site of SARS-CoV-2 infection. The WashUMed team found that nasal delivery created a strong immune response throughout the body. The treatment proved to be especially powerful in the nose and respiratory tract, blocking the infection from becoming established inside the body. 

“We were happily surprised to see a strong immune response in the cells of the inner lining of the nose and upper airway — and a profound protection from infection with this virus,” said study senior author Dr. Michael S. Diamond. “These mice were well protected from disease. And in some of the mice, we saw evidence of sterilizing immunity, where there is no sign of infection whatsoever after the mouse is challenged with the virus.”

To develop the vaccine, the researchers inserted the spike protein of the coronavirus inside of another virus called an adenovirus. This adenovirus usually causes the common cold, but the scientists tweaked it so that it was unable to cause illness. 

The modified adenovirus carries the spike protein into the nose, so that the body can launch an immune defense against SARS-CoV-2 without becoming sick. In an effort to boost the number of antibodies produced, the researchers incorporated two mutations into the spike protein that stabilize it in a specific shape.

“Adenoviruses are the basis for many investigational vaccines for COVID-19 and other infectious diseases, such as Ebola virus and tuberculosis, and they have good safety and efficacy records, but not much research has been done with nasal delivery of these vaccines,” said study co-senior author Dr. David T. Curiel. 

“All of the other adenovirus vaccines in development for COVID-19 are delivered by injection into the arm or thigh muscle. The nose is a novel route, so our results are surprising and promising. It’s also important that a single dose produced such a robust immune response. Vaccines that require two doses for full protection are less effective because some people, for various reasons, never receive the second dose.”

Unlike vaccines and other drugs that would simply reduce the severity of COVID-19, the new nasal treatment appears to potentially stop the viral infection before it even starts. In the mice, nasal delivery completely prevented infection in both the upper and lower respiratory tract – the nose and lungs.

While the study is very promising, the researchers cautioned that the vaccine has only been studied in mice so far.

“We will soon begin a study to test this intranasal vaccine in nonhuman primates with a plan to move into human clinical trials as quickly as we can,” said Dr. Diamond. “We’re optimistic, but this needs to continue going through the proper evaluation pipelines. 

“In these mouse models, the vaccine is highly protective. We’re looking forward to beginning the next round of studies and ultimately testing it in people to see if we can induce the type of protective immunity that we think not only will prevent infection but also curb pandemic transmission of this virus.”

The study is published in the journal Cell.

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By Chrissy Sexton, Earth.com Staff Writer