Covid tests whilst fasting

Lateral flow tests and PCR tests are pivotal to the strategy adopted by many countries to prevent the spread of coronavirus. The lateral flow test involves inserting a dry swab into the nostrils (about half an inch) and then testing the swab immediately. The PCR test involves swabbing the back of the throat and the nostril and then sending the swab to be tested in a laboratory.

Neither the lateral flow nor the PCR invalidate the fast.

1. The swabs used in both types of test are dry and do not contain any food or other substance. Therefore, swabbing the back of the throat or nostril does not constitute eating or drinking as nothing is swallowed.
2. Swabbing the throat may produce saliva that is swallowed. However, it is clear that swallowing saliva was not considered as eating or drinking at the time of the Prophet and did not invalidate the fast. For more please see https://www.collectiveijtihad.org/blog/fasting-and-medication
3. The process of taking the test can be said to be similar to dry brushing of teeth, which has been permitted by Shia jurists.