COVID-19(54) convalescent plasma(47) Blood donors(29) Donor(28) donors(28) SARS-CoV-2(28) positive(28) Treatment(27) conducted(27) Blood(25) age(23) Blood Group(21) India(19) material(19) plasma(18) convalescent(17) neutralizing antibody(17) blood donor(17) Patient(16) IgG(15) pandemic(15) Asymptomatic(15) Prospective Study(15) highest(15) COVID(13) Prevalence(13) titre(13) Infection(13) CCP(12) antibody(12)