Is it permissible to pray Salatul-Istikharah regarding taking the coronavirus vaccine, due to fear of its side effects which its manufacturers have warned against?

Istikhara (guidance-seeking prayer) is for matters where a person does not know the right course of action. As for matters whose goodness or evil is known, there is no need for Istikhara. Istikhara has no place in what is obligatory, forbidden, or disliked. Rather, it is performed for recommended acts and permissible matters. If someone is not clear about the best course of action regarding taking a vaccine dose or refraining from it, it is legislated for them to seek guidance from Allah the Almighty.