According to e-healthme, a reporting site which is based on reports by the FDA and self-reporting of actual patients, on May 22, 2013--
90,168 people reported to have side effects when taking Tysabri.
Among them, 665 people (0.74%) have died.http://www.ehealthme.com/ds/tysabri/death
359 people are currently reported to have PML.http://chefarztfrau.de/?page_id=716
But there have been more Tysabri deaths documented, linked to antibody reactions, lethal ...