A new comparison study in PNAS from NIAID intramural scientists clearly shows that for SARS-CoV-2, nasal vaccination – particularly in two doses – has clear advantages over muscular delivery in laboratory mice. The vaccine tested uses an old immune-activation concept: modified vaccinia virus Ankara (MVA), which is a licensed smallpox and monkeypox vaccine, and is being actively pursued as a vector, or carrier, to deliver a viral protein for other infectious diseases. For this vaccine candidate, the MVA vector delivers the spike protein of SARS-CoV-2, which sits on the surface of the virus, to spur an immune response.
