The answer to stopping the coronavirus may be in the nose

The answer to stopping the coronavirus may be in the nose

The Covid-19 vaccines authorized for use today have been developed at an unprecedented speed and have exceeded expectations in their success. Billions of people protected have avoided severe symptoms, hospitalizations, and deaths. These vaccines are a scientific success that does not measure.

However they could be better.

The enemy has evolved, and the world needs next-generation vaccines to respond. This includes vaccines that completely prevent infection with the Corona virus.

When the first mRNA vaccines were licensed in December 2020, the world was dealing with a different kind of pandemic. The dominant strain spread has a relatively low ability to spread among people. At the time, mRNA vaccines not only provided powerful protection against severe disease and death, but were also highly protective against infection and virus spread as well.

But SARS-CoV-2 continued to mutate, in doing so giving rise to variants that were more contagious and able to circumvent protective antibodies, causing widespread infection, despite increased levels of immunity from previous vaccines and infections. Fortunately, after the booster vaccine, mRNA vaccines are still highly effective in preventing hospitalizations and deaths, including against the highly infectious Omicron variant.

Therefore, one might wonder, if we can eliminate so many risks of disease and severe death through a combination of existing vaccines and treatments, why should we worry about infection?

Even mild infections can develop into long-term Covid, with people experiencing long-term debilitating symptoms. The data also suggests that groups such as older adults who have been vaccinated but have not received their boosters may continue to be at greater risk of worse Covid-19 outcomes.

Regular infections can cause major disruptions to people’s lives, affecting their ability to work and keep their children in school. There is also no guarantee that people with Omicron will still be protected against infection with future variants.

One of the changes that could make vaccines more effective is if they can stop the virus in its tracks, immediately after it enters the body. This can completely reduce the infection, as well as the spread of the virus.

Currently available Covid-19 vaccines are injected into the muscles of the arm and are highly capable of fighting the virus once people are infected. But they were not successful in preventing people from becoming infected at first. To do this, you ideally want to prevent the virus from spreading directly at the site where people are infected: the nasal cavity.

Groups of scientists, including myself, are working on nasal Covid vaccines for this very reason. Ideally, the nasal vaccine could enter the mucous layer inside the nose and help the body make antibodies that pick up the virus before it has a chance to attach to human cells. This type of immunity is known as sterilizing immunity.

By picking up viruses directly at the site of infection, antibodies stimulated by nasal vaccines can give the body a head start in fighting the virus before it causes symptoms. Not only can nasal vaccines be better positioned to prevent infection, they can also develop the same type of immune system protection as other vaccines, and are even stronger because this immune memory is the gateway to the virus. These vaccines can create highly protective memory B cells, which produce faster and better antibodies for future infections, and memory T cells, which help kill infected cells and support antibody production.

Making these types of vaccines has always been considered more difficult. The mucous layer is a formidable barrier. The body also does not generate a strong immune response simply by spraying any conventional vaccine into the nose. The approved flu vaccine, called FluMist, uses weakened viruses to reach nasal cells and stimulate an immune system response. But this approach is not safe to use in people who are immunocompromised.

The good news is that scientists like me believe we’ve found a way around this problem for SARS-CoV-2. We have shown in animal studies that we can spray so-called virus proteins into the nose of a previously vaccinated host and significantly reduce infection in the nose and lungs as well as provide protection against disease and death. Combining this approach with ongoing efforts to develop a single vaccine for a broader group of coronaviruses may protect people from future variants as well.

One big question is how long immunity from the nasal vaccine will last. So far, in animal studies, antibodies and immune memory cells have persisted in the nose for several months. If that immunity wanes over time, as with other vaccines, using a nasal spray as a booster — potentially an over-the-counter — every four to six months may be most beneficial for this epidemic.

This presents similar challenges as other reinforcers, as uptake can be much higher, especially for at-risk groups. Encouraging people to get their boosters is crucial. But the septal booster nasal spray may be lower for many people than the injection with a needle.

The world urgently needs a vaccine strategy in places

Guards outside the gates to prevent viral invaders from infecting us. There are several other nasal vaccine methods in various stages of clinical trials. And any successes we have in developing a nasal vaccine for Covid-19 will not be limited to this virus alone. Nasal spray vaccine strategies can be applied to other respiratory pathogens as well.

While there are some hurdles remaining, the potential immune and general health benefits of nasal spray vaccines are worth focusing on now and for years to come.

2022-05-16 18:12:00

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