Jiang Z, et al. - Researchers conducted this systematic review and meta-analysis to ascertain if cluster schedule leads to a higher risk of local adverse reactions (LARs) and systemic adverse reactions (SARs) than cluster schedule does. The meta-analysis included five observational studies and six interventional studies. No differences were found between the cluster and conventional schedules when analyzing SARs by the number of patients, delayed SARs, grade 2 SARs and LARs. In observational studies, analyzes of SARs by injection, grade 1 SARs and LARs by injection showed that cluster schedule had a lower risk of adverse events than conventional schedule. For AR patients with or without asthma, cluster schedule is as safe as or even safer compared with conventional schedule.