According to a recent study, more than 14% of the world’s population probably has, or has had, tick-borne Lyme disease – an infection that can cause long and debilitating symptoms. That number is set to rise too, as climate and environment changes continue to increase tick populations and distribution. To help prevent some of these cases, pharmaceutical company Pfizer and biotech company Valneva will soon be testing a new vaccine against Lyme disease with 6,000 volunteers across Europe and in the US. Madeleine Finlay speaks to Dr Eoin Healy about what Lyme disease is and how the vaccine works, and hears from a special guest about their own experience of getting ill with the disease.. Help support our independent journalism at theguardian.com/sciencepod