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HYDERABAD, India — On the outskirts of this century-old Indian city, a world away from its congested roads and cacophony, Bharat Biotech’s sparkling modern laboratories are producing a Covid vaccine that will be sprayed into the nose rather than injected. blood.

The vaccines currently available provide strong, long-lasting immunity against severe disease, as many recent studies have shown. But their protection against coronavirus infection is temporary and may decline as new variants of the virus emerge – a failure that regularly causes talk of booster shots.

Nasal vaccines may be the best way to prevent infections in the long run, because they provide protection exactly where it’s needed to fend off the virus: the mucosal linings of the airways where the coronavirus first descended.

Bharat Biotech is among the world’s leading vaccine manufacturers. Its best known product, Covaxin, is authorized to prevent Covid in India and many other countries. But the experimental nasal vaccine could be a real game changer.

Vaccinating entire populations with a nasal or oral vaccine will be faster in the midst of a surge than injections, which require skill and time to administer. A nasal vaccine may be more palatable to most people (including children) than painful injections and can make up for the lack of needles, syringes, and other supplies.

The intranasal vaccines can be “easily administered in mass immunization campaigns and reduce transmission,” said Krishna Ella, president and managing director of Bharat Biotech.

There are at least a dozen other nasal vaccines in development. worldwidesome now in Phase 3 Trials, however, may be Bharat Biotech’s first products to be released. company in January won approval To begin Phase 3 trial of nasal spray in India as a booster for people who have already received two Covid vaccines.

The Omicron variant made it clear that even three doses of vaccine may not prevent infection while providing strong protection against serious diseases. This is because injected vaccines produce antibodies in the blood, and relatively few of them reach the nose, which is the entry route for the virus.

So-called mucosal vaccines would ideally coat the mucosal surfaces of the nose, mouth, and throat with long-lasting antibodies, and there would be many more vaccines. better in preventing infection and the spread of the virus. It’s the difference between putting guards at the gates to ward off intruders and trying to topple them after they’ve stormed the castle.

Jennifer Gommerman, an immunologist at the University of Toronto, said that nasal vaccines are “the only way to truly prevent person-to-person transmission.” “We can’t live forever by protecting vulnerable people and empowering them to keep their antibody levels artificially high.”

nose vaccinations done shown with to protect mice, ferret, hamster and monkeys against coronavirus. A new work last week presented strong evidence to support their use as a booster.

The researchers reported that the intranasal booster induces immune memory cells and antibodies in the nose and throat, enhancing protection from the first vaccine. The study has not yet been published in a scientific journal.

“Our approach is not to use a nasal vaccine as the primary vaccine, but to boost it with a nasal vaccine because then you can boost existing immunity that has already been established,” said Akiko Iwasaki, an immunologist at Yale University who led the study.

Experimental nasal vaccines seemed to be able to fend off a wide variety of coronavirus variants when he and his colleagues used a protein mixture of the novel coronavirus as well as the related SARS virus.

Not included in the study, Dr. “There is some flexibility and there may be more resistance to the virus,” Gommerman said. “And that’s very attractive as we don’t know what the virus will do next.”

Current Covid vaccines are injected intramuscularly and are successful at training immune cells to fight the virus once it enters the body. They produce antibodies called IgG that circulate in the blood and can be sequenced as needed.

However, very few of these antibodies go to the nose and throat, and even the antibodies decrease rapidly.

In contrast, nasal vaccines produce a special set of antibodies called IgA that develop on mucosal surfaces such as the nose and throat. And these antibodies may decrease more slowly.

A vaccine given with a nebulizer can coat the entire airway, including the lungs, with IgA antibodies. Dr. “It’s not just the tip of the nose that is protected,” Iwasaki said.

Increasing evidence supports IgA antibodies as the key to preventing infection. In one study, Dr. Gommerman and colleagues found that only 30 percent of people had detectable IgA antibodies after receiving a second dose of the vaccine.

those who lower IgA levels Within one month of the second dose, they were more likely to develop a breakthrough infection. IgG levels did not seem to have any effect on the outcome.

“Location is really important, and mucosal immunity is really important to ward off infection,” said Michal Tal, an immunologist at Stanford University who participated in the study.

People who become immune due to infection with the virus rather than an injected vaccine tend to be strong. mucosal immunity, at least for a while. This may help explain why they appear. Better fare against Delta variant Dr. Tal said there are more than those who have been vaccinated.

But he warned that trying to get mucosal immunity by getting an infection is dangerous. “The way to give people that kind of mucosal protection really, really, really has to be a nasal vaccine,” he said.

Dr. Tal said injected vaccines are the right approach to build the systemic immunity needed to prevent death and disease, the immediate goal at the start of the pandemic. And the Trump administration has nominated several candidates through Operation Warp Speed.

“It was a good first step, but soon after that we needed intranasal vaccines for reinforcement,” he added. “What I really wish I had was a Warp Speed ​​2.0 for nasal vaccines.”

But developing nasal vaccines is complex. Measuring mucosal antibodies is much more difficult than measuring antibodies in the blood. Quantities are usually low and can fluctuate wildly. For example, the flavor of a delicious meal can dilute mucosal antibody levels, filling the mouth with saliva.

“It’s like a stepchild for vaccine development because it’s difficult,” said Florian Krammer, an immunologist at the Icahn School of Medicine at Mount Sinai, New York, about mucosal vaccines.

The only nasal vaccine approved for respiratory illnesses in the United States is FluMist, and even this one is fraught with problems. FluMist is based on a weakened flu virus, so it works well in children who have never been exposed. But in many adults, the current flu killed the immune-compromised virus and rendered the vaccine ineffective.

Trying to boost the vaccine with an extra ingredient called an adjuvant has inflamed the nasal mucosa and led to Bell’s palsy in some people.

However, saying that these problems will not be a problem for a nasal vaccine using a viral protein, Dr. “Our approach is very different, I don’t think it suffers from that kind of limitation,” Iwasaki said.

Yet there has been little talk about nasal vaccines for Covid in the United States, which has adopted mRNA vaccines made by Pfizer-BioNTech and Moderna.

“Most of these developments are happening in other parts of the world,” he said. an effort to create a nasal vaccine. “The appetite for new vaccines in the US is very low.”

Dr. Gommerman said one reason for the hesitation is that no one knows yet how strong immunity a mucosal Covid vaccine can be and how long it might last.

But mRNA vaccines were likewise a gamble at the start of the pandemic, “I don’t think that’s a good enough reason not to try it,” he said.