The anti-Covid vaccines, developed in ultra-fast times, have avoided deaths, serious illnesses and hospitalizations, as the statistics of all the international health authorities and scientific research suggest, but they could be even better, according to several teams of scientists, and the way to achieve this further advancement could be through the nose. The road is not short, experts admit. But the studies are starting to grow. As well as spray vaccine candidates in development (there are 8 nasal vaccines in clinical development and 3 in phase 3 studies, according to the journal Scientific American online). A promise that follows a slower path, but that could be a little closer to the finish line.
“It is the most difficult vaccination, the most complex modality to develop. But the one that would work best”, explains to Ruetir Salute Mario Clerici, professor of immunology at the University of Milan and scientific director of the Don Gnocchi Foundation. Where are we at? Among the works evaluating this approach there is a recent one, published in ‘Science Translational Medicine’ and visible online, in which a team of scientists explains how an anti-Covid vaccine administered by mouth or nose can help raise the barrier against contagion from Sars-CoV-2. The authors define it as a viable strategy, capable of reducing both disease and airborne transmission. The article reports the results of an animal test with an adenoviral vector vaccine candidate. There is a need for vaccines that also act as a barrier to transmission, especially with the advent of variants – and Omicron sub-variants, such as 4 and 5 – increasingly contagious.
The international media also devote focus to the topic, one of the most recent is the one that in the ‘New York Times’ hosts the intervention of a scientist, Akiko Iwasaki, at the head of a group from Yale University that works precisely on this: a new approach vaccination with systemic vaccines that train the immune response of the whole body, followed by boosters administered directly into the nasal cavity, to provide special protection in the part of the body most affected by Sars-CoV-2 infection.
“Ideally a nasal vaccine – explains the expert – could enter the mucus layer inside the nose and help the body to produce antibodies that capture the virus before it has a chance to attach itself to people’s cells. By capturing the virus itself. at the site of infection, antibodies induced by nasal vaccines can give an advantage in the fight against “SARS-CoV-2″ by acting before it causes symptoms. ” These vaccines, Iwasaki continues, “can establish highly protective memory B cells and memory T cells.”
A study just made available on the ‘BioRxiv’ platform, signed by German scientists, sought to compare different approaches to vaccination, evaluating the potential differences in systemic and mucosal immunity conferred by different vaccines and different vaccine regimens that mix various types of shield products. . The various options were tested in hamsters and all regimens containing the live attenuated vaccine candidate sCPD9, which is administered intranasally, showed superior efficacy.
The robust immunity elicited was evident in a wide range of immune parameters, from rapid viral clearance to strong systemic and mucosal humoral responses and rapid recall of memory T cells from lung tissue. show that the use of live attenuated vaccines can offer advantages over available Covid-19 vaccines, particularly when applied as a booster “after a primary course, is the conclusion of the experts.
“The key point – comments Clerici – is that the virus enters through the respiratory mucous membranes. With a nasal vaccine, the vaccine compound is brought in place and the presence of IgA antibodies is stimulated. These are mucosal and cover the tissues of the upper respiratory tract. and prevent the virus from coming into contact with them. Therefore the virus does not enter the body. To give another example, a high concentration of vaginal IgA protects against HIV infection with heterosexual transmission “.