I hate to tell you that your worries are not over. Someone that makes it past this first hurdle will face a risk this fall when cold and flu infections abound due to immune priming and enhancement. Of course it will be blamed on "variants" instead of the jabs.

The best thing they could do is get their vitamin D levels up - I mean around 70-80 nmol/l. Vitamin C is important along with RDA levels of Zinc which is about 10mg a day. Jarrow Formulas makes a good product that is Zinc and Copper. Both of those minerals balance each other. It is not good to take Zinc alone for too long because it will lower Copper levels that can lead to anemia. Someone that has a history already of anemia needs to be careful when trying to load up on Zinc. Medicinal mushrooms are also of benefit for not only dealing with infection but as a cancer preventative. These supplements can be taken safely by people with a variety of medical conditions and that are on several medications - especially blood thinners.

The bottom line is that if they want to protect themselves against the changes in their immune systems that the vaxines caused, they need to help their immune systems overcome the deficits they will for sure be faced with until their bodies can try to return to a more normal state - that is as long as they do not get any more vaccines - any vaccines! By the way, a huge VA study linked flu vaccines to an increased risk of coronaviral infections. So, the COVID jabs are not the only vax that needs to be considered here. We are destroying our God given natural immune systems by all this man-made interference. It will kill us.

Good luck. I am reposting a link another anon posted further up this thread. It is really good. I hope it will be useful to help convince your parents this is not a good idea. Hat tip to @BraddahBrad 18 Reasons I Won't Be Getting a Covid Vaccine