**1. Introduction**

In December 2019, a newly emerged respiratory diseases associated with pneumonia from Wuhan, China caused by a initially named 2019 novel coronavirus (2019-nCoV) [1] and recently referred as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) producing coronavirus disease (COVID-19). Thus 2019-nCoV, caused a pandemic across the globe, the World Health Organization (WHO) declared it as a 'Public Health Emergency of International Concern (PHEIC)' on January 30th, 2020. Considering its devasting threats worldwide, WHO declared SARS-CoV-2 as a pandemic spread on March, 2020 [2]. As per WHO guidelines, no effective therapy is available to treat devastating SARS-CoV-2, the treatment is mainly symptomatic and supportive. Thus, the current lack of evidence for effective treatment and vaccines, led to the re-emergence of classical and historical intervention called convalescent

plasma (CP) immunotherapy. Since the early 20th century, a passive CP immunization strategy has been used in prevention and control of infectious disease [3]. CP seems to be the first line of defense against the SARS-CoV-2, since it has been more successfully adapted in the treatment of SARS, MERS (Middle East Respiratory Syndrome) and H1N1 pandemic with significant efficacy and safety. In order to combat current devastating pandemic, this review mainly highlights on the clinical immunotherapy studies conducted in the fields of neutralizing antibodies (nAbs) predominately present in convalescent plasma (CP) for the treatment and management of COVID-19.
