American vaccines that transformed public health over 250 years: 'Outweighs harm'

Before the first successful vaccine was developed in 1796, Americans had little protection against deadly infectious diseases like smallpox, measles and diphtheria . Over the next 250 years, vaccines helped eliminate or dramatically reduce many vaccine-preventable infectious diseases , preventing millions of illnesses, infections and deaths. "There is a reason that vaccines are widely considered to be the greatest public health tool after sanitation," Fox News senior medical analyst Dr. Marc Sie