Finland advances experimental Lyme disease vaccine targeting ticks

Finland is conducting a late‑stage trial of a new vaccine against tick‑borne Lyme disease (borrelioosi). Pharmaceutical firms Valneva and Pfizer are developing the candidate, which aims to protect the most common Borrelia strains in Europe. The study involves nearly 10,000 participants worldwide, with Finnish sites including MeVac in Helsinki, Terveystalo in Turku and seven FVR research centres. Lead medical expert Santtu Heinonen says the vaccine could meet a significant disease burden. Unlike traditional vaccines, it works by inducing antibodies in the human blood that, when taken up by a feeding tick, block bacterial transmission. Preliminary data suggest a booster dose yields 70‑75 % efficacy against infection. The developers plan to apply for a marketing authorisation soon, but the product is not yet available in pharmacies.

Separately, Finland’s national vaccination programme has been expanded from August to offer a free water‑virus (vesirokko) vaccine to adults who lack immunity. Only about 1–3 % of the adult population are estimated to be unprotected. The vaccine is recommended especially for pregnant women, immunocompromised patients, those about to start strong immunosuppressive therapy, and healthcare workers. It consists of two doses given at least three months apart and can be booked through the Central Uusimaa health‑care region.