Target trial emulation without matching: a more efficient approach for evaluating vaccine effectiveness using observational data
无需匹配的目标试验模拟：利用观察数据更高效评估疫苗有效性
Real-world vaccine effectiveness has increasingly been studied using matching-based approaches, particularly in observational cohort studies following the target trial emulation framework. Although matching is appealing in its simplicity, it suffers important limitations in terms of clarity of the target estimand and the efficiency or precision with which is it estimated. Scientifically justified causal estimands of vaccine effectiveness may be difficult to define owing to…