Genetic engineering now enables the design of live viral vaccines that are potentially transmissible. Some designs merely modify a single viral genome to improve on the age-old method of attenuation whereas other designs create chimeras of viral genomes. Transmission has the benefit of increasing herd immunity above that achieved by direct vaccination alone but also increases the opportunity for vaccine evolution, which typically undermines vaccine utility. Different designs have different epidemiological consequences but also experience different evolution. Approaches that integrate vaccine engineering with an understanding of evolution and epidemiology will reap the greatest benefit from vaccine transmission.

现在，基因工程可以设计可能传播的活病毒疫苗。一些设计仅修饰单个病毒基因组以改进古老的衰减方法，而其他设计则创建病毒基因组的嵌合体。传播的好处是可以提高畜群免疫力，使其高于单独直接接种所能达到的免疫力，但同时也增加了疫苗进化的机会，这通常会破坏疫苗的实用性。不同的设计具有不同的流行病学后果，但也会经历不同的演变。将疫苗工程学与进化和流行病学相结合的方法将从疫苗传播中获得最大的收益。