claim: attenuated influenza virions expressing the sars- cov-2 receptor-binding domain induce neutralizing antibodies in humans
evidence_1: a single-dose intranasal inoculation of mice with δna(rbd)-flu elicits serum neutralizing antibody titers against sar-cov-2 comparable to those observed in humans following natural infection (~1:200).", "the resulting δna(rbd)-flu virus can be generated by reverse genetics and grown to high titers in cell culture.")