The family Coronaviridae is known as one of the most important etiologic factors for severe acute respiratory diseases for 21st-century human beings. The members of this family are enveloped, single-stranded, positive-sense RNA viruses (26–32 kbp length), and also have many spikes proteins on their surfaces that mediate virus entry into the cells (1). Coronaviruses have a broad spectrum of the host including avian, humans, and several mammals such as bats, camels, mice, cats, dogs, and anteaters (2). Among them, several coronaviruses (CoVs) such as 229E, OC43, NL63, HKU1, SARS-CoV-1, MERS-CoV, and more recently severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect human (3). Before 2002, CoVs were known only as of the causes of common cold, however, in the 21st century, the large pandemic of betacoronavirus revealed that these RNA viruses can cause the life-threatening severe respiratory diseases (4). In 2002, the first pandemic, severe acute respiratory syndrome (SARS), was caused by SARS-CoV-1, so that had the mortality rate about 10% (5). The second pandemic, Middle East respiratory syndrome (MERS), was occurred by MERS-CoV in 2012, with mortality rate about 35% (6). In December 2019, a new member of betacoronavirus, 2019 novel coronavirus (2019-nCoV) emerged in Wuhan, China, causing a severe pneumonia, that was called coronavirus disease 2019 (COVID-19) (7). The clinical manifestations of COVID-19 are fever, dyspnea, myalgia, and invasive multi-lobular lesions (in chest radiological findings), and these are much like SARS and MERS diseases (4, 8). The nucleotide sequence of the 2019-nCoV genome is very similar (88%) with both bat-SL‐CoVZC45 and bat‐SL‐CoVZXC21 genomes. In addition, the phylogenetic analysis revealed that the similarity of its genome with both SARS-CoV-1 and MERS-CoV is 79% and 50% respectively (9). SARS-CoV-2 is a highly contagious virus, and rapidly spread worldwide. In March 2020, World Health Organization (WHO) announced the COVID-19 pandemic, and nowadays more than 13 million cases are infected by this virus (10). Despite the rapid spread of the virus, but so far there is no an approved vaccine or drug approved by Food and Drug Administration (FDA) against COVID-19 (11). The lack of a protective vaccine and yet the need to avoid of spread of virus has been led to use of alternative strategies such as convalescent plasma therapy (CPT) for the treatment of patients (12). Historically, passive immunization is as one the therapeutic protocols against infectious agents, and first was used in 1880s (13). In passive immunization, the individuals who recover from an infectious disease are investigated, and the convalescent plasma (CP) with high titers of neutralizing antibodies is used for other similar patients, so that leads to reduce the clinical sings, treatment duration and mortality rate (14). According to review of literature, CP has been used for treating diseases such as Diphtheria, Spanish influenza, Ebola, West Nile fever, SARS, and MERS, and has been satisfactory results in amelioration and reduction of mortality rate (15–19). Due to advantages such clinical efficacy, viral therapy, reducing death, and low side effects, CPT is considered as a suitable therapeutic option in complications such infectious diseases, immune deficiencies, allergies, and autoimmune diseases (13, 20, 21). Furthermore, based on studies, it is demonstrated that CP has the satisfying results in improving and increasing the survival of COVID-19 patients (22). CPT is one of the most reliable therapeutic options during the outbreaks of infectious agents, in particular in the absence of the appropriate vaccine (12). Recently, FDA has announced that CP can be used as a trustworthy way in cases of widespread outbreak of COVID-19 (23). In the present meta-analysis, we fulfilled a comprehensive evaluation study about the effects of CP on clinical improvement, increase of discharged cases, as well as reducing mortality of infected patients by viruses SARS-CoV-1, MERS-CoV, and SARS-CoV-2.