Mucosal vaccination induces protection against SARS-CoV-2 in the absence of detectable neutralizing antibodies.

A candidate multigenic SARS-CoV-2 vaccine based on an MVA vector expressing both viral N and S proteins (MVA-S + N) was immunogenic, and induced T-cell responses and binding antibodies to both antigens but in the absence of detectable neutralizing antibodies. Intranasal immunization with the vaccine diminished viral loads and lung inflammation in mice after SARS-CoV-2 challenge, which correlated with the T-cell response induced by the vaccine in the lung, indicating that T-cell immunity is also likely critical for protection against SARS-CoV-2 infection in addition to neutralizing antibodies.