Blood and plasma treatment

Hi my partner has had Ms for 15 years never had any kind of relapse blind in one eye and apart from fatigue led a normal life, after having the second COVID jab he almost immediately began to complain of being confused co ordination and mobility became restricted within 3 weeks he Was paralysed down the left and unable to stand or walk he’s Been in Hospital a month steroids have not worked completed blood and plasma treatment and still no improvement …. Has anyone had any experience of how long the treatment takes effect please