8 The efficacy of passive antibody therapy was associated with the concentration of NAbs in plasma or antibodies of recovered donors. 5 Passive antibody therapy, such as plasma fusion, was successfully used to treat infectious viral diseases, including SARS-CoV virus, 6 influenza viruses, 7 and Ebola virus. The level of NAbs has been used as a gold standard to evaluate the efficacy of vaccines against smallpox, polio and influenza viruses. Virus-specific NAbs, induced through either infection or vaccination, have the ability to block viral infection. Neutralizing antibodies (NAbs) play important roles in virus clearance and have been considered as a key immune product for protection or treatment against viral diseases. Currently, no licensed vaccine or drugs are available to prevent or treat COVID-19 infection, and most infected patients have been treated with supportive care. 4 Although the estimated mortality rate of COVID-19 was lower than SARS and MERS, the number of deaths associated with COVID-19 has already surpassed those of SARS and MERS owing to the extremely high transmissibility of SARS-CoV-2 coronavirus. About 3.4% of patients died from respiratory failure or multiple organ failure. Another 5% of patients, especially those over 60, or with comorbidities, progressed to critical condition.
1 About 81% of infected patients showed only mild symptoms, but 14% of them had severe symptoms such as dyspnea, high respiratory frequency and low blood oxygen saturation. 2, 3 As of March 27, 2020, it had caused a total of 509,164 cases of infection and resulted in 23,335 deaths worldwide. 1 The etiological agent of COVID-19 was identified as a SARS-related coronavirus designated as SARS-COV-2 coronavirus.
The outbreak of coronavirus disease 2019 (COVID-19) in December 2019 has spread around the world and become a global pandemic.