HYDERABAD, India – On the outskirts of this centuries-old Indian city, a world away from congested roads and noisy noises, Bharat Biotech’s gleaming state-of-the-art laboratories are producing a vaccine. may Covid be sprayed into the nose instead of injected into the bloodstream.
Vaccines are now available that confer strong, long-lasting immunity against severe illness, as several recent studies have shown. But their protection against infection from the coronavirus is fleeting and could falter as new variants of the virus emerge – a failure that has prompted talk of routine booster vaccinations. often.
Nasal vaccines may be the best way to prevent long-term infection, as they provide protection exactly where it is needed to fight the virus: the lining of the airways, where the coronavirus first reaches.
Bharat Biotech is one of the world’s leading vaccine manufacturers. Its most famous product, Covaxin, is authorized to prevent Covid in India and many other countries. But its experimental nasal vaccine could become a real game changer.
Immunizing the entire population with a nasal or oral vaccine is quicker in the middle of a mutation than with injection, requiring skill and time to perform. Nasal vaccines may be more palatable to many people (including children) than painful injections, and will avoid shortages of needles, syringes, and other materials.
“Intranasal vaccines can easily be used in mass vaccination campaigns and reduce disease transmission,” said Krishna Ella, president and chief executive officer of Bharat Biotech.
There are at least a dozen other nasal vaccines in development all around the worldsome of them now in Phase 3 experiment. But Bharat Biotech’s may be the first to hit the market. In January, the company win approval to start a phase 3 trial of the nasal spray in India as a booster for people who have received two doses of the Covid vaccine.
The Omicron variant made it clear to all that even three doses of the vaccine, while they provide strong protection against severe disease, may not prevent infection. That’s because the injected vaccine produces antibodies in the blood, relatively few of which reach the nose, the virus’ entry route.
The so-called mucosal vaccine would ideally coat the mucosal surfaces of the nose, mouth, and throat with long-lasting antibodies, and there would be many better prevent the infection and spread of the virus. It was the difference between planting guards at the gate to deter intruders and trying to oust them after they had stormed the castle.
Jennifer Gommerman, an immunologist at the University of Toronto, says the nasal vaccine is “the only way to really prevent person-to-person transmission”. “We can’t live forever sheltering vulnerable people and pushing them to keep their antibody levels artificially high.”
Researchers report that a nasal booster drug induces immune memory cells and antibodies in the nose and throat, and enhances protection from primary vaccination, the researchers report. The study has yet to be published in a scientific journal.
Akiko Iwasaki, an immunologist at Yale University, who led the study, said: “Our approach is not to use the nasal vaccine as the primary vaccine, but to boost it with a nasal vaccine. because then you can take advantage of the existing immunity that has already been created.”
When she and her colleagues used a mixture of proteins from the novel coronavirus as well as the related SARS virus, their experimental nasal vaccine appeared to be resistant to a wide range of coronavirus variants.
Dr Gommerman, who was not involved in the study, said: “There is some flexibility, and possibly more resistance to the virus. “And because we don’t know what the virus is going to do next, that’s incredibly intriguing.”
Current Covid vaccines are injected into the muscle and work to train immune cells to outperform the virus after it enters the body. They make antibodies called IgG that circulate in the blood and can be made as needed.
But some of these antibodies make their way to the nose and throat, and even these antibodies quickly wane.
In contrast, nasal vaccines produce a special set of antibodies, called IgA, that thrive on mucosal surfaces such as the nose and throat. And these antibodies may disappear more slowly.
The vaccine is delivered with a nebulizer that can cover the entire airway, including the lungs, with IgG antibodies. “It’s not just the tip of the nose that is protected,” says Dr. Iwasaki.
Mounting evidence supports IgA antibodies as key to preventing infection. In one study, Dr. Gommerman and her colleagues found that only about 30% of people had detectable IgA antibodies after a second dose of vaccine.
People who have lower IgA levels within a month of the second dose are more likely to have a breakthrough infection. IgG levels do not appear to affect the results.
“The location is really important, and the immunity of the mucosa is really important for protection from infection,” said Michal Tal, an immunologist at Stanford University who was involved in the study.
But she warns that trying to achieve mucosal immunity by getting an infection is dangerous. “The way for people to get that kind of mucosal protection really, really, really should be with the nasal vaccine,” she said.
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Vaccination is the right approach to generate the systemic immunity needed to prevent death and disease, an urgent goal at the start of the pandemic, Dr. Tal said. And the Trump administration has opened up a number of candidates through Operation Warp Speed.
She added: “It’s a good start, but we need to prepare a nasal vaccine to strengthen the child soon after. “What I really wish we had was Warp Speed 2.0 for the nasal vaccine.”
But developing a nasal vaccine is complicated. The measurement of antibodies in the mucosa is much more difficult than the quantification of antibodies in the blood. Amounts are usually low and can fluctuate wildly. For example, the aroma of a delicious meal can flood the mouth with saliva, diluting the mucosa’s antibody levels.
“It’s like a stepchild to develop a vaccine, because it’s so hard,” says Florian Krammer, an immunologist at the Icahn School of Medicine at Mount Sinai, New York.
The only nasal vaccine approved in the United States for respiratory illnesses is FluMist, and even that has solved the problem. FluMist is based on a weakened influenza virus, so it works well in children who have never been exposed. But in many adults, existing immunity to the flu that has killed the virus has weakened and made the vaccine ineffective.
Attempting to boost the vaccine with an additional ingredient, called an adjuvant, inflames the lining of the nose and leads to Bell’s palsy in some people.
But those problems won’t affect the nasal vaccine that uses viral proteins, says Dr. Iwasaki: “Our approach is so different, I don’t think it suffers from such limitations.”
However, there is still little talk of a nasal vaccine for Covid in the United States, which has already accepted an mRNA vaccine made by Pfizer-BioNTech and Moderna.
Dr. Krammer, who participated in an effort to create a nasal vaccine. “The appetite for the new vaccine in the US is very low.”
Gommerman said one reason for hesitation is that no one knows yet how strong immunity from the mucosal Covid vaccine is, and how long it might last.
But an mRNA vaccine was also a gamble at the start of the pandemic, she noted: “I don’t think that’s a good enough reason not to try.”
https://www.nytimes.com/2022/02/02/health/covid-vaccine-nasal.html The Covid vaccine we need right now may not be a cure