Does radiation therapy affect the immune system?

I can’t imagine that it doesn’t affect your immune system at all. @mimzy I can’t imagine how miserable you are to get Covid again. I can’t say that it was because of radiation, but I would be extra careful for sure. I have read that this years variant is escaping previous immunity in many folks.
Are you feeling any better today?

Covid keeps mutating. If you didn't get the last shot, you are not up to date. Effectiveness also wanes over time. Thr newest CDC guidelines recommend being vaccinated twice per year for those over 65 and those with serious health issues. The newest shot which just became available last month is not an exact match for the latest mutation but is close. Covid mutates too quickly to keep up. That said, no, I don't believe radiation affects your immune system. My oncologist had me defer dental cleanings until a month after completing chemo treatments but had no issues with dental visits during my 33 radiation treatments which followed. Regardless, your immune system would have recovered before now. I'm sorry you're going through this.

Of course, it affects your immune system in a very negative way. You need to eat super healthy, do lots of exercise now and stay out of crowded places!!

You may have been exposed by some thoughtless and ill-mannered person or persons in a waiting room, someone who did not even bother to cover his mouth with his hands while coughing, much less wear a mask. Covering your mouth while coughing used to be basic common sense and good manners. One guy in the lab waiting area, who was doing his best to hack up an entire lung, was wearing a T-shirt that said, "My mother said I could be anything I wanted to be when I grew up, so now I'm an a**hole." What can you say to a man who already has his own number and acts accordingly? Instead, I had to take all the precautions. See photos. I stayed home when not at a Mayo appointment because chemo lowers immunity and I knew I did not want Covid during chemo. Not sure how radiation impacts the immune system.

https://www.breastcancer.org/managing-life/immune-system/cancer-treatments/radiation-therapy

I am not allowed to express my thoughts about the thoughtless, who like to be mean and aggressive in my area because I wear a mask. I am certainly allowed to laugh when you express those thoughts.
I wear a mask indoors to protect others, my husband who has a bone marrow cancer, and one of my dearest friends who has the same cancer.
Sadly around here, most don’t even think about that, they like to make it a political thing.
When I was on chemo and as my doctor explained, “you have about 4 white cells right now”, I wore a mask and/or kept my distance from humans. If you are like I was, you need it to mask all the smells in the world anyway. 😂😂
I love your glasses too. I don’t believe radiation significant affects your immune system, but it can’t help and chemo definitely does.
How far out from chemotherapy are you? Are you done with radiation now?

Yes, radiation affects the immune system at many levels. If your Covid infection is within five days Paxlovid would ease the symptoms dramatically.