Unlike PCR testing, isothermal nucleic acid amplification doesn't require any changes in temperature. One of the popular types of this test is reverse transcription loop-mediated isothermal amplification, short for RT-LAMP. It is a one-step molecular assay that can quickly replicate sequences of the targeted RNA, making it useful for diagnosing RNA viruses. This was previously used for MERS-CoV and SARS-CoV, and it has also been shown to be effective in diagnosing the coronavirus. This technology was invented in 2000 and has been used for diagnosing viruses like the hepatitis B virus and the West Nile virus . However, because of its complexity, the primers are more difficult to design.