How Sequencing Covid-19’s Viral Genome Helps Hunt for Variants

To keep up with changes to the virus that causes Covid-19, scientists are using a technology called genomic sequencing. The process starts with a Covid-19 test. Some samples that test positive for the coronavirus in a laboratory are pulled aside and sent off for sequencing, a review of the virus’s genetic material that can take as little as a day or more than a week. The SARS-CoV-2 genome has about 30,000 individual building blocks to decode, compared with about three billion in the human genome. Sometimes researchers have equipment to sequence the samples on hand or nearby. But often samples must be shipped elsewhere, which can take days. “Just the sheer logistics of shipping these samples from where they’re tested to where they’re going to be sequenced, that can be huge,” said Pavitra Roychoudhury, an acting instructor in the laboratory medicine and pathology department at the University of Washington.