Intramuscular vaccinations do not significantly prevent infection of the upper respiratory immune compartment (mucosal IgA antibodies, not humoral covered by Ig

Intramuscular vaccinations do not significantly prevent infection of the upper respiratory immune compartment (mucosal IgA antibodies, not humoral covered by IgG). The efficiency against infection by sars-cov-2 is about 20%. That means 80% get infected. Now, the intramuscular injection vaccines do provide tissue resident B (+IgG antibodies) and T cells in the body serum (humoral, not mucosal) immune compartment and this has been proven to prevent serious (hospitalization) by covid-19 with decent (>50%) efficiency. These IgG antibodies do not seep into the upper respiratory (mucosal compartment) and provide protection there though; only the lower lungs. But infection? The only good mitigation, lacking a proper intranasal vaccine like India has, is wearing a well fit and sealed mask like an N95 with good practices.