The infection and immune life-cycle for Influenza A and similar enveloped viruses such as SARS-CoV-2 are varied and may depend on many factors. Several quotes from various reference materials included below provide a summary of the infection and immune life-cycle.
“Three requirements must be satisfied to ensure successful infection in an individual host: <\/p>\n\n\n\n
“To infect its host, a virus must first enter cells at a body surface. Common sites of entry include the mucosal linings of the respiratory, alimentary, and urogenital tracts, the outer surface of the eye (conjunctival membranes or cornea), and the skin”
“Following replication at the site of entry, virus particles can remain localized, or can spread to other tissues”
“Viruses that escape from local defenses to produce a disseminated infection often do so by entering the bloodstream (hematogenous spread). Virus particles may enter the blood directly through capillaries, by replicating in endothelial cells, or through inoculation by a vector bite. Once in the blood, viruses may access almost every tissue in the host. Hematogenous spread begins when newly replicated particles produced at the entry site are released into the extracellular fluids, which can be taken up by the local lymphatic vascular system (Fig. 7). Lymphatic capillaries are considerably more permeable than circulatory system capillaries, facilitating virus entry. As the lymphatic vessels ultimately join with the venous system, virus particles in lymph have free access to the bloodstream. In the lymphatic system, virions pass through lymph nodes, where they encounter migratory cells of the immune system.”
Please read the following<\/a> for more details regarding viral entry.<\/strong><\/p>\n\n\n