culture: SARS-CoV-2, S5p2 stock
For next-generation sequencing (NGS) library preparation, RNA (25-100 ng) was mixed with random oligonucleotide primers using the NEBNext First Strand Synthesis Module kit for Illumina (NEB) and incubated for 10 min at 94C. NGS of samples was performed by a commercial service provider (GenomeScan, Leiden, the Netherlands) while including appropriate quality controls after each step of the procedure.