Hi Annebis,
It's normal to feel a little hesitant about something that might affect someone you care about. As far as I know, COVID-19 vaccine trials haven't included people with endometriosis. But it's considered safe for most people with underlying health conditions based on the research that has been done. And even though the vaccine hasn't been studied in all groups, the CDC and other health officials consider the risk of COVID-19 to outweigh any potential side effects.
There is data to show that the vaccine may not be as effective in people who are immunocompromised. But endometriosis is not considered a true autoimmune condition.
There is a rare chance of a serious allergic reaction with any vaccine, but endometriosis isn't likely to increase that. But it would be worth talking to your doctor if your daughter has had a reaction to other vaccines, like the flu shot.
I can offer you my own experience. I know people with ulcerative colitis, arthritis, and endometriosis who've gotten the vaccine. None reported any serious side effects or flares of their symptoms. I also have endo, am 39, and received both of the Moderna doses. I had some common (but pretty uncomfortable) side effects for about 40 hours. That includes your usual fever-like symptoms: soreness at the injection site, fever, muscle aches, joint pains. It was clear my immune system was responding, so I felt rundown for a few days after that, almost like I had a cold. But I was back to normal about 5 days after my second shot, and I feel totally fine now — 2 1/2 weeks later. I did have an irregular period in between my first and second dose, something that isn't uncommon for me. My periods usually get out of sync when I'm under any kind of stress — physical or mental!
I know it can be hard to navigate all this when the vaccine is new. Don't hesitate to talk about all of your concerns with your or your daughter's doctor. That's what they're there for! They can explain exactly how the vaccine works, and give you feedback about what they've seen with other patients. Wishing you and your family well! - Keri (endometriosis.net team member)