As explained Jose Jimenez, a coronavirus researcher in the Infectious Diseases department at King’s College London, the infection enters the upper respiratory tract, where IgA antibodies are produced, and then passes into the lower respiratory tract (lungs), where IgG antibodies are generated. Intramuscular or intradermal vaccines, such as those currently in use in Spain, mainly stimulate IgG antibodies, which protect the lower respiratory tract (lungs), avoiding severe symptoms, but the virus can multiply freely in the upper tract.
Therein lies the difference between “functional immunity” – the person is contagious but suffers fewer symptoms – and “sterilizing immunity”, which prevents infection, and is what vaccines administered through the nose look for. As the professor of Molecular Medicine explained Eric Topol in “Scientific American”, “they are designed to strengthen the defenses in the mucosa, which triggers the production of an antibody known as immunoglobulin A [IgA], which can block infection ”.
Nasal vaccines would not only protect the vaccine recipient, the spread of new variants and the possible appearance of strains would also be prevented more transmissible or resistant to vaccines.
“This virus enters our body primarily through the respiratory tract, so if you administer the vaccine intranasally, you immunize that area and the protection is greater. We are going for an intranasal vaccine with a very powerful single dose ”, explained Luis Enjuanes, head of one of the three vaccine projects at the CSIC. It is not the only project in progress. In the United States, an intranasal formula based on an attenuated SARS-CoV-2 is being developed, in which two virulence genes have been eliminated, and which, according to virologist Javier Cantón, “would be the definitive vaccine”, since “the infection would stop at the very gateway of the virus ”. In addition, the Chinese pharmaceutical company CanSino this week received authorization for clinical trials of its intranasal vaccine.
Nasal vaccines promise great results, but in the longer term. The president of the Spanish Society of Immunology, Marcos LopezHe recalled in “El País” that they will serve to “refine and improve the immunizations we already have” if, as expected, this coronavirus ends up being endemic and requires vaccinating every few years. “They have to generate systemic and local immunity,” he pointed out on Twitter. Jose Gomez Rial, Immunologist at the Hospital Clínico de Santiago-. Its development is more complex, we know very little about the immune system in mucous membranes ”.
Beyond vaccines, there is other research that points to the nasopharyngeal muscosa, such as that of Maria Luisa Coderch, a researcher at the Institute of Advanced Chemistry of Catalonia, who tries to design a molecule capable of preventing the absorption of the coronavirus in the throat and nose. It would be an aerosol that would protect the toilets like a second mask.
The Galician neuroscientist in Houston (USA) Sonia Villapol has underlined the importance of nasal formulas, since the coronavirus enters the brain of people through the nose, as demonstrated by a study by the German hospital Charité published in “Nature Neuroscience”. One of these drugs is a nasally administered lipopeptide that blocks ACE2 receptors, the entry of SARSCoV2 into cells. It prevented infection in ferrets, according to a study published in “Science.” “This, taken to the clinic, would protect people from COVID, and without a vaccine,” Villapol stressed.
Israeli scientists have also developed an anti-COVID spray, known as EXO-CD24, which cured 29 out of 30 severe or moderate patients at Tel Aviv’s Ichilov Hospital.
There are also dashed hopes. The Spanish Agency for Medicines and Health Products, after a query from the Official College of Pharmacists of Madrid, withdrew from pharmacies a nasal spray called Taffix that promised to reduce up to 97% of viral particles in the nasal cavity. The Spanish Society of Otorhinolaryngology also questioned its reliability.
Eddie is an Australian news reporter with over 9 years in the industry and has published on Forbes and tech crunch.