Covid vaccine and running stamina

Im a 69 year old active lady who last year started running through the Walk To Run program.
Although in good shape if still took me many months before I could run a full 30 minutes non stop.
I increased this to 35 minutes 2-3 times a week, lost 10 lbs in the process and was truly very, very happy with my progress.

I then in January had the booster Moderna vaccine after 2 Phizer previously. None of these shots seemed to bother me for more 24 hours. After the booster shot I took couple of days rest before heading out for my usual morning run but found I could only complete 20 minutes and was utterly exhausted. After that for the next week or two, each run got worse and worse.

At my wits end, I finally decided to start the Walk To Run program again from scratch and find myself unable to barely complete 7 minutes non stop run with 3 minutes walk 3 times over.

It is now June and 5 months on from when I had the booster shot, I feel I have lost all of the stamina that I worked so hard to gain, nothing else in my life has altered in any other way. I dont feel tired in general, only terrible fatigued when I run.

Could the lack of stamina be from having the Moderna booster shot and if so how long will it last?

Thanks, unhappy runner.

Nicole's reply:
Hi, I'm really sorry that you are struggling when you have done so well in getting to the level that you were prior to the booster.

I really am not qualified to say if the booster injection caused your lack of running stamina. I do however know of others in the same situation as you and also of others who caught Covid and who are now struggling to get back into running. It's a frustrating place to be.

If you haven't already, I would go and see your doctor and get a checkup. It might not be related to the vaccine at all and hopefully it is something that can be sorted quickly. Good luck and I hope you are back running soon.