First, about hardening. It has been proven that hardening (that is, periodic exposure to cold air or cold water), even if the correct technique is followed, gives a slight adaptation to cold. Considering the heavy load on the thermoregulatory systems of the body, which lowers its nonspecific resistance to infections (read - there is a great risk of getting sick) and the small benefit from the procedure, I would say that even healthy people should not do this, what is there for HIV-infected people. By the way, another moment. AIDS and HIV infection are different concepts, AIDS is the terminal (last) stage of this and develops in 10 on average years after infection. AIDS just implies the danger of infection by opportunistic (passing) microorganisms. If anything, this does not mean that you can walk naked for 10 years in winter and nothing will happen.
Everything is very individual. I would very much like the decision on hardening to be discussed with the attending infectious disease doctor, but our doctors are either very busy or generally have little idea of what hardening is and what it is for. I can only share my experience, but I do not impose it on you, because there are really many nuances in hardening. I have been sick with HIV since 99th year and every year, like clockwork, a cold came to me in a rather severe form and I had to drink a bunch of not cheap antibiotics, and a couple of years ago in the fall we turned off the hot water and after training we had to wash under cold water. That's how I got used to pouring myself in ice water after training and running. Over the past two years I have suffered quite easily one cold and then they brought a sore throat to me almost home, but after a week I was already running and exercising without medication. , which is very important, because of the need to drink a bunch of antibiotics during a cold, which facilitated the work of the kidneys and liver, and if you constantly drink ARVT it is very important. time.
Short answer: you need to individually consult with your doctor.
Hardening is generally quite poorly understood. And almost all information about its benefits, strictly speaking, is not supported by any serious research. A study of the contrast shower on professional athletes showed, perhaps, a subjective feeling of cheerfulness, without any improvement in objective indicators. There are health risks there, and quite serious (vasospasm, for the most part).
And even more so when swimming. In general, winter swimming should be considered as a completely extreme sport, and not a health-improving procedure. Yes, positive differences in health are found in walruses, but it cannot be ruled out that, firstly, walruses, in principle, can better monitor their health, play sports and lead a healthier lifestyle, and secondly, in view of the fact that winter swimming is quite strong stress for the body, only people with reinforced concrete health can regularly practice it.