1. Question: [Thursday, 2^nd Adar 1, 5782]

Am I allowed to take a home Covid test on Shabbos to see if I am sick and to determine as to whether I can go out or need to be in isolation? The test involves placing a Q-tip into my mouth and nostril, which is then saturated in a liquid and poured into a designated area on the test tube. This causes a chain reaction in which a dark color spreads throughout the display window of the test and causes a dark line by its top to remain. If it is positive, a second line will be formed in the bottom of the display window.

Answer:

One should not take a home Covid test on Shabbos unless one is feeling sick and taking the test would have some medical value in how one would treat himself on Shabbos. Certainly, if one is bedridden, one may take the test on Shabbos even if he is simply doing so to determine if he needs to be in isolation on Shabbos.

Explanation: Taking a Covid test on Shabbos, as well as taking a pregnancy test on Shabbos, raises the question of whether causing the lines to be created on the display window consists of the dyeing and writing prohibition. On the one hand, it is forbidden for one to even temporarily write or dye an item on Shabbos, and perhaps the dark line which is created is considered at least a temporary form of dyeing which is forbidden. Likewise, it is forbidden to write even symbols which are not numbers or letters on Shabbos, even temporarily, and hence perhaps causing the line to be created, being that it represents a symbol, is forbidden due to the writing prohibition. On the other hand, one can argue that the matter is a mere Gerama and is done in a way of a Shinuiy, of which one has no intent to create the line and is simply there to figure out whether one is positive or negative, and the matter is not a real ink but rather a chemical reaction which has no substance, and therefore perhaps there is room to be lenient. As well as, based on Admur in Kuntrus Achron 302:1, since the stick is designated for this purpose and is thus not commonly dyed, therefore its does not contain a dyeing prohibition.  Practically, this matter is debated amongst today’s Poskim, and in our conclusion we rule that it is better to avoid taking such tests on Shabbos due to the above halachic worries, and it should only be done in a time of medical need, such as if one is sick in which case we anyways permit rabbinical prohibitions to be done on his behalf

Sources: Lenient opinion: Shearim Hametzuyanim Behalacha 91; Beir Moshe 8:24; Tzitz Eliezer 10:25; SSH”K 33:20; Stringent opinion: Michzeh Eliyahu 1:65; Nishmas Hashabbos 290; Rav SZ”A SSH”K ibid; Piskeiy Teshuvos 320:27