Considering most viruses, including the ones associated with SARs-COV-2, enter the body through the mucosa and infect the cells and molecules present in the mucosal membranes, nasal vaccines are seen as an effective solution for the same.
On the contrary, intramuscular vaccines or injected vaccines fail to trigger such immune response from the mucosa and depend on immune cells from other parts of the body.
Apart from that, nasal vaccines are easier to administer and may provide easy immunity. An effective nasal jab can not only protect against COVID-19, but also directly interacts with T-cells that exist in the nose and the throat and targets the immune cells present in the mucosal membrane.
As per Bharat Biotech, their intranasal vaccine candidate, which is soon to enter Phase I clinical trials, has proven effective and is said to provide high levels of protections in mice studies.