SFTPD and COVID-19: Addressing a significant research gap, we identified the C/T polymorphism (rs721917, T > C) of the SP-D gene within the Iranian population using the tetra-amplification refractory mutation system polymerase chain reaction (T-ARMS PCR) method.<h4>Results</h4>Statistical analysis showed a significant association between the SP-D rs721917 TT genotype and T allele with increased COVID-19 severity and hospitalization risk.