Vaccinations in early life elicit variable antibody and cellular immune responses, sometimes leaving fully vaccinated children unprotected against life-threatening infectious diseases. Specific immune cell populations and immune networks may have a critical period of development and calibration in a window of opportunity occurring during the first 100 days of early life. Among the early life determinants of vaccine responses, this review will focus on modifiable factors involving development of the infant microbiota and metabolome: antibiotic exposure, breast versus formula feeding, and Caesarian section versus vaginal delivery of newborns. How microbiota may serve as natural adjuvants for vaccine responses and how microbiota-derived metabolites influence vaccine responses are also reviewed. Early life poor vaccine responsiveness can be linked to increased infection susceptibility because both phenotypes share similar immunity dysregulation profiles. An early life pre-vaccination endotype, when interventions have the highest potential for success, should be sought that predicts vaccine response trajectories.

生命早期的疫苗接种会引起不同的抗体和细胞免疫反应，有时会使完全接种疫苗的儿童无法免受危及生命的传染病的侵害。特定的免疫细胞群和免疫网络可能在生命早期的前 100 天内有一个发展和校准的关键时期。在疫苗反应的早期生命决定因素中，本综述将重点关注涉及婴儿微生物群和代谢组发育的可改变因素：抗生素暴露、母乳喂养与配方奶喂养以及新生儿剖腹产与阴道分娩。还回顾了微生物群如何作为疫苗反应的天然佐剂以及微生物群衍生的代谢物如何影响疫苗反应。生命早期较差的疫苗反应可能与感染易感性增加有关，因为两种表型具有相似的免疫失调特征。当干预措施最有可能成功时，应寻求生命早期的疫苗接种前内型来预测疫苗反应轨迹。