Variants in Cryptosporidium parvum nucleotide sequences isolated from recurrent COVID-19 patients. The results of DNA sequencing of C. parvum isolates and alignment of them. C. parvum (ref): ATCC PRA-67DQ™; C. parvum var 1 was isolated from recurrent COVID-19 patients. The most variable region consists of between 120 bp and 200 bp.