The feasibility of convalescent plasma therapy in severe COVID-19 patients: a pilot study

Kai Duan; Bende Liu; Cesheng Li; Huajun Zhang; Ting Yu; Jieming Qu; Min Zhou; Li Chen; Shengli Meng; Yong Hu; Cheng Peng; Mingchao Yuan; Jinyan Huang; Zejun Wang; Jianhong Yu; Xiaoxiao Gao; Dan Wang; Xiaoqi Yu; Li Li; Jiayou Zhang; Xiao Wu; Bei Li; Yanping Yu; Wei Chen; Yan Peng; Yeqin Hu; Lianzhen Lin; Xuefei Liu; Shihe Huang; Zhijun Zhou; Lianghao Zhang; Yue Wang; Zhi Zhang; Kun Deng; Zhiwu Xia; Qin Gong; Wei Zhang; Xiaobei Zheng; Ying Liu; Huichuan Yang; Dongbo Zhou; Ding Yu; Jifeng Hou; Zhengli Shi; Saijuan Chen; Zhu Chen; Xin-xin Zhang; Xiaoming Yang

The first key factor associated with CP therapy is the neutralizing antibody titer. A small sample study in MERS-CoV infection showed that the neutralizing antibody titer should exceed 1:80 to achieve effective CP therapy (12) . To find eligible donors who have high levels of neutralizing antibody is a prerequisite. Cao (23) et al showed that the level of specific neutralizing antibody to SARS-CoV decreased gradually 4 months after the disease process, reaching undetectable levels in 25.6% (IgG) and 16.1% (neutralizing antibodies) of patients at 36 months after disease status. A study from the MERS-CoV infected patients and the exposed healthcare workers showed that the prevalence of MERS-CoVIgGseroreactivity was very low (2.7%), and the antibodies titer decreased rapidly within 3 months (24) . These studies suggested that the neutralizing antibodies represented short-lasting humoral immune response and plasma from recently recovered patients should be more effective. In the present study, recently recovered COVID-19 patients, who were infected by SARS-CoV-2 with neutralizing antibody titer above 1:640and recruited from local hospitals should be considered as suitable donors. The median age of donors was lower than that of recipients (42.0 vs. 52.5 years). Among the nine cases investigated, the neutralizing antibody titers of five patients increased while four patients kept the same level to 1:640 within two days. The antibody titers in CP in COVID-19 seem thus higher than those used in the treatment of MERS patient (1:80) (12) .