A safe, effective vaccine against Covid-19 could resurrect jobs, send kids back to classrooms--change our lives. But how safe and effective? And how quickly can we have it? Dr. Robert Gallo, the AIDS-research pioneer now leading virus science at the University of Maryland----argues we could get much of the benefit by inoculating people with an old, very cheap drug--the oral polio vaccine developed seven decades ago. Gallo contends it would trigger our ‘innate immunity’--the body’s emergency response when a threat shows up.