Summary: they can only work, and with no or fewer adverse effects, if they don't contain toxic products and are used by people who have minimally good lifestyle habits, or are on a sincere path to improving theirs. Even then, for many of them, immunization is not significantly guaranteed, or long-lasting, above all because of the high rate of mutation, especially of viruses.
In other words: those who don't do this, at least most of them, have a greater chance of not having sufficient “protective” effects from the vaccines and/or even experiencing far more, and potentially more serious, adverse effects from them, simply because they are “trying to stimulate” an organism that doesn't have the basic conditions to withstand minimal aggressions and structure an adequate immune response!
It's as simple as that.
*Post to answer once and for all those who are asking me about “what I think about vaccinations, H1N1, HPV, flu and so on".
** BEFORE thinking about vaccinations, optimize your lifestyle, because this is what really “protects” you, improving your defenses, your immune system!
Read more about vaccines here: https://icaro.med.br/?s=vacina



