Scientists hope nasal vaccines will help halt Covid transmission

Among the first in the world to receive Moderna's dual-variant vaccine is a person who will get a Covid booster dose in the UK next month. Scientists say there is a misconception that the vaccine is an upgrade on what has been done before.

The evolution of the Covid virus to be more transmissible and better evade immunity is more advanced than any other innovative vaccine. The current generation of vaccines is necessary to protect us against illness and death. We are in a situation similar to running on a treadmill at a fast pace.

Scientists are calling for a renewed focus on vaccines that are delivered through a spray up the nose. They think that the best way to stop Covid transmission is to have a vaccine that protects against it.

Sandy Douglas, a member of the team that delivered the Oxford/AstraZeneca said, "Solving this problem of inducing really effective immunity to block transmission is such an important challenge, it really deserves to receive significant attention and energy."

The current vaccines cause a response in the immune system, which helps to prevent serious illness. The failure of injected vaccines to produce immunity in the respiratory tract is the main shortcoming.

Benjamin Goldman- Israelow is an infectious diseases researcher at Yale.

A nasal vaccine is the most realistic way to break the chain of Covid transmission, according to many. A phase 1 trial of a nasal version of the Oxford/AstraZeneca vaccine is being conducted.

Douglas said that the challenge should be taken seriously. He said that they were trying to do better than exposure to the virus would do.

There isn't a lot of experience with the vaccine. Flumist is a spray that works by entering the cells of the nose and triggering an immune response.

This kind of vaccine needs to hit a sweet spot where enough virus is delivered to jumpstart the immune system, but not so much that the virus starts replicating and results in the person becoming infectious, which is what happened in the UK recently. Douglas said that people are not very excited about going down with a new vaccine.

There is always a chance of unexpected side-effects with new vaccine approaches. The vaccine used in Switzerland in the 1990s was withdrawn after being linked to facial paralysis. There's a little bit more of the unknown with the safety profile, but it may turn out to be better for the vaccine.

There is no consensus on how effective a vaccine can be. The interim chief medical officer of the US based company that is preparing to take a Covid vaccine into a phase 2 trial said that a complete or near complete block of transmission would be preferable.

A reduction in transmission can make a huge difference. A reduction in transmission would lead to a reduction in infections.

How you would measure reduction in transmission in a clinical trial is one of the harder questions to answer. As far as we know no one has tried to conduct an experiment with human volunteers to see if the vaccine reduces Covid transmission.

Prof Akiko Iwasaki, an immunologist at Yale, co-founded the company Xanadu Bio to develop a nasal booster vaccine that does not require live viruses.

The team hopes to conduct a phase 1 trial of the vaccine next year. Iwasaki has called for an operation to deliver a nasal vaccine at lightning speed, similar to the one used for this stage of the Pandemic.

She said that a small academic lab doesn't have manufacturing, regulatory, distribution capabilities. The public and private sectors need to support this.

Douglas concurs. Companies are reluctant to take the risks in vaccine development. He said that they don't get the full benefits. Not enough research is done if they have to bear the costs and risks.