More accurate than a rapid antigen test and almost as quick, India's CRISPR ‘Feluda' COVID-19 test that changes colour on detection of the SARS-CoV-2 virus could be a cheaper, faster and simpler alternative to an RT-PCR diagnosis, say scientists. Named after Satyajit Ray's famed detective, the Feluda test, which is priced at Rs 500 and can deliver a result in 45 minutes, is able to differentiate SARS-CoV-2 from other coronaviruses even if genetic variations between them are minute.