With only 15% of the world population fully vaccinated, the fight against the pandemic is far from over … Oral vaccines are particularly interesting for developing countries. But they could also provide a boost to immunization in wealthy countries, where fear of injections is a factor, often unnoticed, in reluctance to be vaccinated.
According to a recent survey, nearly 19 million Americans who do not want to be vaccinated would agree to do so in pill form if the option existed. “For the vaccine to work really well, as many people as possible need to take it,” says Nadav Kidron, head of Israeli pharmaceutical company Oramed.
Other benefits include less plastic waste and potentially fewer side effects.
Survive the digestive tract
Despite the theoretical positives, few oral vaccines have seen success because the active ingredients tend not to survive as they pass through the digestive tract. Among the vaccines that are an exception to this rule are those for diseases that are transmitted through the mouth or the digestive system. There is thus an effective oral polio vaccine.
Oramed, founded in 2006, believes it has overcome technical obstacles by developing a capsule capable of surviving the highly acidic environment of the digestive system. Long before the pandemic, it developed this technology for the delivery of “oral insulin”, explains Nadav Kidron, referring to the vital drug for diabetics which until now has only been administered by injection.
According to the company, its technique, developed with Nobel laureate in chemistry Avram Hershko, who is part of its scientific advisory committee, protects oral insulin with a capsule whose coating degrades slowly. The capsule also releases molecules that prevent enzymes from attacking insulin in the small intestine.
This oral insulin has been tested on hundreds of patients in clinical trials in the United States, and is currently in “phase III”, the most advanced. The company uses the same mechanism for its oral vaccine against covid, developed by its subsidiary Oravax.
To elicit an immune response, company scientists have developed synthetic particles similar to the coronavirus. These mimic the key structures of the pathogen: the “Spike” protein, the envelope protein and the membrane protein.
Most vaccines currently licensed, such as Pfizer or AstraZeneca, are based on the Spike protein alone, making them less effective over time because the virus’s Spike protein mutates. By targeting multiple parts of the virus, Oravax’s vaccine could be variant resistant, Nadav Kidron said.
The company has requested permission to launch trials in several countries, such as South Africa, and hopes to start its first in Israel within a few weeks, if the health ministry allows it.
Nadav Kidron says he foresees a role for the vaccine first in developing countries that have not yet purchased enough of the current vaccines. If it works, it would also represent hope for future oral vaccines, he adds. “Imagine… The flu shot comes to you in the mail, you take it and it’s over.”
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