DISCLAIMER: This is just halacha-theory and not searching for a p'sak

Would taking a lateral flow test on Shabbos be absolutely forbidden due to the melacha of tzoveya - dyeing?

After taking the swab and sticking it up one's nostril, the tester then places the swab in a container of solution and then pours it on to a small pad which generates a reaction. The process is described as follows:

The test kit is a hand-held device with an absorbent pad at one end and a reading window at the other. Inside the device is a strip of test paper that changes colour in the presence of COVID-19 proteins (antigens).

I am aware of this question here about the pregnancy test.

There in @jake's answer he draws a parallel to diabetic test sticks. He writes there:

One issue with taking such a test is tzovaya, as usually the test involves chemicals in the stick changing colors by reacting to the urine. R' Ribiat, in 39 Melachos, with regard to clinical test sticks used by diabetics to determine urine-sugar level, cites Sh'miras Shabbos K'Hilchasa (33:20), who is unsure about this (see footnotes 81-83 there), and recommends that one not urinate directly onto the stick, but rather such that the urine comes by way of g'rama onto the stick.

Now I appreciate this is not exactly the same scenario and equally, given the small area in which one drops the solution, it would be quite hard to do it indirectly.

So therefore:

Is it a definitive that this is simply not allowed due to tzoveya, or due to the pandemic is there a difference as unlike the case of pregnancy and diabetes one needs to be mindful of potentially infecting others and there is more halachic leniency? Should one proceed with some form of shinui, or in such a scenario is it advised to ask a goy to do the test for you?

  • Not sure if this is authoritative but here’s something I found. israelnationalnews.com/News/News.aspx/313127
    – Chatzkel
    Commented Sep 30, 2021 at 1:47
  • Diabetes is clearly more of a reason to take a test since you need the info now. Covid testing can generally be delayed, even it means quarantining
    – Double AA
    Commented Sep 30, 2021 at 3:01


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