Historical records from late Imperial China document sustained practices of variolation—the intentional introduction of material from smallpox lesions to induce a milder infection and subsequent protection. Smallpox caused substantial morbidity and mortality globally before eradication in 1980, and communities used measures such as isolation and variolation prior to vaccinia-based vaccination. The reviewed article focuses on the chronology, technical evolution, and the medical explanatory frameworks that made variolation intelligible within Chinese medicine, and compares Chinese documentation with records from India and other regions.
Surviving textual evidence shows that variolation was practiced in China at least by the Chenghua–Longqing period of the Ming dynasty (1465–1572 CE). Specific records document practitioners in Taiping County, Anhui Province during the Longqing reign (1567–1572 CE), and contemporaneous practitioners in Jiangxi Province. Evidence indicates that the practice became established in Jiangxi between the Chenghua and Longqing eras and subsequently spread across the Yangtze Basin, including Anhui, Zhejiang, Jiangsu, and Hunan provinces. During the Qing dynasty, variolation grew more widespread and at times received imperial support; for example, the Kangxi Emperor recruited physicians from Jiangxi to perform inoculation at court and in Mongolia.
Chinese sources describe three successive inoculation approaches:
Accounts also record intranasal administration of inocula, indicating alternative routes of deliberate exposure. These documented methods reflect a diversity of practical approaches used historically in China to induce protective infection.
Late Imperial texts contain detailed descriptions of inoculum selection, cultivation of a mature inoculum, preservation conditions for variolation materials, timing of inoculation, eligible populations, contraindications, and postinoculation care. Techniques such as repeated passage of inocula and intranasal administration are recorded as empirical efforts to improve consistency and reduce risk. The reviewed literature included eight traditional Chinese medicine works selected because they offered sufficiently detailed operational descriptions of inoculation techniques and protocols.
Variolation in China was interpreted through established medical concepts. Two frequently cited explanatory ideas in the texts are fetal toxin (胎毒) and seasonal pathogenic qi (时气). These frameworks made the rationale for variolation intelligible within contemporaneous medical thought and supported local innovation in preventive practice. The alignment between theory and practice in the records is presented as evidence that variolation methods arose indigenously within the Chinese medical environment rather than being solely imported.
Both China and India are recognized as early centers of variolation, but the article highlights that the earliest detailed surviving records are from China. Written documentation from India that can be definitively dated is mainly from the 18th century, whereas Chinese records documenting methods and chronology predate those sources. From the 17th to 18th centuries, variolation practices circulated beyond East Asia via multiple pathways; late 17th-century Russian envoys reported practices traced to China, and variolation was documented later in Circassia, Ottoman territories, North Africa, and the Americas. The article notes that the prior international focus on South Asian practices has underemphasized the technical detail and explanatory frameworks preserved in Chinese sources.
The investigators retrieved bibliographic records of ancient traditional Chinese medicine (TCM) on variolation from the General Catalogue of Ancient Traditional Chinese Medical Classics and obtained full texts from compendia and databases (including the Zhonghua Yidian and Shidian Ancient Classics). They selected eight works that provided detailed descriptions of inoculation techniques and 12 works documenting changing theories of smallpox across historical periods from Han to Qing dynasties. The authors conducted in-depth readings, analyzed terminology precisely, and extracted structured information on methods, inoculum handling, timing, contraindications, and postinoculation regimens. Because the study used published and archival materials without human subjects or identifiable data, ethical approval and informed consent were not required.
The collected evidence indicates an early, regionally elaborated variolation tradition in China with progressive technical refinement and an explanatory framework rooted in Chinese medical thought. Documentation of multiple inoculation modalities (garment/blanket, lymph, and scab-derived inoculum), intranasal administration, and repeated passage techniques illustrates empirical attempts to optimize safety and effectiveness. The presence of detailed procedural descriptions in Chinese texts, predating many South Asian documentary records, supports a central role for China in the early history of prophylactic inoculation. The authors emphasize that integrating Chinese scholarship into broader international histories of variolation can enrich understanding of technical development and indigenous explanatory models.
The article acknowledges that early origin claims tracing variolation back to Tang- or Song-era events lack independent corroboration; the best-supported chronological evidence begins in the mid-to-late Ming dynasty. The study’s conclusions are based on surviving texts and archival materials; gaps in the record and the retrospective nature of some later accounts limit certainty about the very earliest origins. Within those constraints, the reviewed documentation provides consistent evidence of indigenous development, technical refinement, and widespread dissemination of variolation originating in China and spreading beyond East Asia in the 17th and 18th centuries.