The textbook view of vaccination is that it functions to induce immune memory of the specific pathogen components of the vaccine, leading to a quantitatively and qualitatively better response if the host is exposed to infection with the same pathogen. However, evidence accumulated over the past few decades increasingly suggests that vaccines can also have non-specific effects on unrelated infections and diseases, with important implications for childhood mortality particularly in low-income settings. Furthermore, many of these non-specific effects, as well as the pathogen-specific effects, of vaccines show differences between the sexes. Here, members of the Optimmunize consortium discuss the evidence for and potential mechanisms of non-specific and sex-differential effects of vaccines, as well as their potential policy implications. Given that the non-specific effects of some vaccines are now being tested for their ability to protect against COVID-19, the authors also comment on the broader implications of these trials.

教科书中关于疫苗接种的观点是，疫苗的作用是诱导疫苗中特定病原体成分​​的免疫记忆，如果宿主暴露于相同病原体的感染，则会在数量和质量上产生更好的反应。但是，过去几十年积累的证据越来越多地表明，疫苗还可以对无关的感染和疾病产生非特异性作用，对儿童死亡率尤其是在低收入环境中的死亡率具有重要意义。此外，疫苗的许多这些非特异性作用以及病原体特异性作用显示出性别之间的差异。在这里，Optimmunize联盟的成员讨论了疫苗非特异性和性别差异作用的证据和潜在机制，以及它们潜在的政策含义。