The largest review of the available evidence on the quadrivalent, or four-strain, HPV vaccine Gardasil, has found no evidence of any serious short-term or long-term safety issues. Bringing together the findings from clinical trials, post-licensure studies and data presented at scientific meetings but not yet published, the researchers focused particularly on autoimmune diseases, nervous system disorders, anaphylaxis, blood clots and stroke – but none of them is caused by the vaccine, they found.