Discussion on the composing principle of "Qingfei Paidu Decoction"in the treatment of anti-COVID-19 from the theory of syndrome-differentiation of the six meridians in Treatise on Febrile Diseases

The coronavirus disease 2019(COVID-19)was a newly discovered infectious respiratory disease and characterized by wide prevalence,high incidence rate and fast progress and dangerous,which belonged to the category of"cold-wet plague"in TCM.The onset of COVID-19 was caused by pestilence,which mingled with seasonal cold-dampness and invaded the human body when external defensive qi was weak and then leaded to the accumulation of Yang qi.Different from exogenous pathogenic factors transmitted from the external to the internal or followed the transmission law of Wei,Qi,Ying and Xue,the nature of pestilence belonged to the category of pathogenic fire,spreading as soon as possible,from the external to the internal and from the upper and lower part of triple energizer,even to every part.At the very beginning,the pestilence attacked from the Taiyang meridian into the Yangming meridian quickly,or straight into the three Yang meridian,which was called"triple-yang combination of diseases".Manifestations of fever,aversion to cold and pain of body were conformed to the exterior syndrome of Taiyang,as well as manifestations of fullness and discomfort in chest,vomiting and spitting and diarrhea were conformed to the syndrome of half-interior-half-exterior;And symptoms manifested as high fever,faint,and abdominal fullness and constipation were conformed to the syndrome of Yangming;But sometimes,there was cold-dampness surrounding the exterior at the beginning along with intense interior pathogenic fire.Or at the beginning,the exterior factors invaded into three Yin meridians quickly while have not been eliminated,which may lead to the syndrome of inner blocking causing collapse or Jue exhaustion.The most typical syndrome of COVID-19 was triple-yang combination of diseases,which was often seen in mild,moderate and part of severe cases.Hence"Qingfei Paidu Decoction"was prescribed especially for this kind of syndrome.Its accurate efficacy has been proved by that mild cases converting to severe cases in the mobile cabin hospital have been effectively restrained and thus the progression of the disease has blocked.Composition analysis showed that Mahuang decoction with Maxing Shigan decoction was to relieve exterior Taiyang syndrome,Xiaochaihu decoction was for harmonizing half-superficies and half-interior Shaoyang syndrome,and large dose of gypsum was used to clear interior heat of the Yangming meridian,and Shegan Mahuang decoction and Xiaoqinglong plus gypsum decoction was for lowering the adverse qi and resolving fluid,and Wuling San was for warming the triple energizer and transforming qi and draining water."Qingfei Paidu Decoction"was an syncretic innovation of classical prescriptions from Treatise on Febrile Diseases,which was not made up of herbs but multiple concordant prescriptions helping to get twice the result with half the effort,so that the"cold-wet plague"can be quickly discharged.