Epidemic models often generate new terms or phrases to describe their behavior. Two of these, “herd immunity” and ”flattening the curve”, have been widely misunderstood and misused in the COVID epidemic by media, policy makers and even epidemiologists, who should know better. They have been held up as goals of public health management, but there is a deep down-side of each. Achieving herd immunity is just reducing the number of susceptible hosts for the pathogen to the point that the chance of an infected individual contacting a susceptible to transmit the pathogen isN too small to support the persistence of the disease. This is achieved at the cost of terrible human suffering or by vaccination that is measurably costly and it is difficult to achieve adequately high vaccination rates. Flattening the curve just trades acute pain for chronic pain. Reducing peak suffering and health care cost is replaced by an extended period for each, with only very small reduction in summed morbidity and cost. It can allow more time for the evolution of new strains that might be less sensitive to established therapies or vaccines.

Unfortunately, we are lacking good models of the evolution of coronaviruses. Our immune systems, augmented by vaccines and prophylactic public health measures are a major force of natural selection on any virus. Yet these measures are always reacting to existing strains of the pathogen whose evolution they influenced, when they should be anticipating future strains. Our ingenious new RNA vaccines can direct our immune systems to select for or against individual viral proteins or sub-structures. Along with innovative public health policies they could be guiding the evolution of the virus, instead of reacting to it. It is within the realm of possibility to guide the evolution of infectious disease pathogens toward forms that are perhaps more transmissible but produce mild or negligible symptoms. There are many examples of such “prudent pathogens” that have evolved to persist by not harming, or even by benefitting their hosts. This approach, led by models of the evolution of the virus, should be a more active line of research.