Contrary to what you read J&J has the least side effects of all the vaccines. My husband, son and I all got it and had zero side effects and we all had Covid before as well.
There seems to be a push for the mRNA vaccines instead of J&J.I know this isn't popular to post but there are some serious concerns with mRNA technology in past vaccine tests. It's why it has never been used on humans before. I sought out the J&J because it doesn't have that technoloogy and it was tested when virus variants were more prevalent. It is, however, hard to find because of how the other ones are pushed.