Table 2.

Advantages and disadvantages of conventional adaptive immune response vaccines versus innate immune-stimulating vaccines through use of “old” LAVs for the SARS-CoV-2 pandemic

Characteristic	Innate broadly specific LAVs	Adaptive (specific) vaccines
Economics	Cheap, but likely little market value	Expensive, but great market value
Availability	Not a problem for many of these vaccines	Unavailable during the emergence of a new pathogen
Speed of action	Immediate	Weeks
Safety record	Known and mainly very safe	Unknown for new vaccines (needs 1 to 2 y or longer)
Efficacy	Clearly for their target pathogen and numerous results for broader effects	Efficacious for SARS-CoV-2 in standard setting, still unclear in high-risk groups and for what duration
Durability	Weeks to months to years	Extremely variable a few months to a lifetime
Memory	Thought to be none; but recent results for bacillus Calmette–Guérin reveal innate immune memory (trained innate immunity)	Strong for B cells (antibodies) and T cell responses