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The humoral immune response to SARCoV-2 can last at least 12 months after diagnosis in most recovered patients, a latest study by Chinese researchers revealed. This could help in the development of COVID-19 vaccines and therapy. 

To investigate the duration of the humoral immune response in convalescent COVID-19 patients, research teams led by Yang Xiaoming, Chairman of Sinopharm China National Biotec Group (CNBG), a Sinopharm subsidiary, and Zhang Xinxin, a professor from the Shanghai Jiao Tong University, conducted a 12-month longitudinal study of 1,782 plasma samples from 869 convalescent plasma donors in Wuhan, the first place in the world to test specific antibody responses.  

Twelve months is the longest observation period for SARS-CoV-2 antibody reaction kinetics, CNBG said in a statement released on Wednesday.  

The statement also announced that Yang and his team are conducting research on SARS-CoV-2 variants. 

The results were published on Tuesday in Nature Communications. It shows that positive rate of the IgG antibody against receptor-binding domain of the spike protein (RBD-IgG) to SARS-CoV-2 in COVID-19 convalescent plasma donors exceeded 70 percent for 12 months after diagnosis. 

The level of RBD-IgG decreases with time stabilizing at 64.3 percent of the initial level by the 9th month. Moreover, male plasma donors produce more RBD-IgG than female at the early stage following diagnosis, and the age of the patients positively correlates with the RBD-IgG titer, according to the report. 

A strong positive correlation between RBD-IgG and neutralizing antibodies was also identified. These results facilitate our understanding of SARS-CoV-2-induced immune memory to promote vaccine and therapy development, read the report. 

Effective vaccination is well known as the safest path towards herd immunity. Most COVID-19 vaccine candidates employ the same antigens of the original SARS-CoV-2, implying that the type and kinetics of neutralizing antibody response induced by vaccination are similar to those induced by the original live virus, according to the report. 

China has administered about 1.3 billion doses of COVID-19 vaccines as of Tuesday, while the total number of shots administered globally is about 3.29 billion, according to data website Our World in Data.