I went to a seminar about Lemtrada and yes you get it infused for 5 days in a row, then come back a year later for a 3 day treatment. You are required to give a blood and urine test every month for 5 yrs because it can ruin your liver and kidneys...most of the time the symptoms and/or abnormal blood work doesn't show up until year 2 and beyond and sometimes irreversible . The UK does use this as a first line of treatment, but the US requires you to have been on at least 2 other DDM's before approving it