The suitable temperature for long-term preservation of nucleic acid samples is 4 degrees Celsius. COVID-19 has strict regulations on the storage temperature and time of nucleic acid samples. According to the Technical Guide for Sample Collection and Detection in COVID-19 issued by the National Health Commission, nucleic acid detection samples should be sent for inspection as soon as possible after sampling. If it can be sent for inspection within 24 hours, it should be stored at 4℃. If it cannot be sent for inspection in time within 24 hours, it should be stored at -70℃. After sampling, the sample shall not be kept for more than 24 hours, and shall be submitted for inspection in time within 4~6 hours.