Together, DNA and RNA make up the nucleic acids found in all living cells including within bacteria, archaea, mitochondria, chloroplasts, and viruses. These are essential for all known forms of life. The coronavirus has its own unique RNA. If you get infected with the coronavirus, it injects its RNA into your cells and forces them to make copies of the virus. The new copies burst out of the cell spread the virus to other cells in your body to make more copies.
Since the pandemic began, scientists developed tests that look for coronavirus RNA in people’s saliva. This is an alternative to the swab tests that involve sticking cotton swabs deep into people’s noses.