outcome(19) conflict(19) Sample(15) COVID-19(14) Patient(13) age(13) significantly(12) hospital(12) Infection(11) participant(11) Tertiary(10) conflict of interest(10) Saudi Arabia(9) SARS-CoV-2(9) dose(8) individual(8) median(8) anti-Spike IgG(8) Participants(8) subject(8) coronavirus(8) positive(8) intensive care(8) vaccination(8) cross-sectional study(8) acute respiratory syndrome(8) patients(8) single-center(8) SARS CoV-2(8) antibody(8)