To get an exact test result, you should gargle in the morning after you get up and before you brush your teeth or have breakfast. This is an efficient way to ensure a reliable diagnosis of COVID-19. Gargling is the ideal method. Rinsing your mouth is the second best choice because it is not as efficient to detect the virus. If you find it difficult to gargle, you can also just rinse your mouth (e.g. children may find it easier to rinse their mouth and not gargle).