@Jez-benign , if you were to receive an answer to this question, I, personally, wouldn't trust the answer. It's best to ask a medical professional, who probably won't know the answer too!
Just generally, we are immuno-compromised, so our immune systems don't work properly. Our immune system can attack us, causing inflammation and nibbling away at the myelin sheaths that protect our nerves.
Our immune systems can be activated when we're fighting an infection, for the duration of the infection. This can cause a flare-up of our MS symptoms, referred to as a "pseudo-exacerbation". This is not therefore a proper relapse, just a temporary flare-up until the underlying infection is cleared.
Let's hope that that's as bad as it might get for those of us, who don't take Disease Modifying Therapies (DMTs). For those taking DMTs, they should review the advice from the MS Society and MS Trust, or the Bart's MS Research Blog.
The following may be useful too:-
Just keep washing your hands and take care.