Antibiotics
There have been some suggestions that prophylactic antibiotic treatment should be given after the removal of ticks that have evidently fed for more than 24 hours. However, except in areas of very high risk where a high proportion of ticks carry invasive strains of the spirochaete, this approach is not justified.
In the case of I. ricinus, prophylaxis is not justified since most ticks are not infected with the spirochaete, transmission may be prevented by early removal of the tick and the vast majority of infections are asymptomatic. The general recommendation is to treat with antibiotics only on presentation of appropriate symptoms (Stanek, and Kahl, 1996. Zentralbl Bakteriol. 289:655-65; Nahimana et al 2004 Eur J Clin Microbiol Infect Dis. 23:603-8., 2; Patey 2007. Med Mal Infect.37:446-55). However, there is some evidence that in the case of I. persulcatus, treatment after a tick-bite can significantly reduce the risk of LB (Korenberg et al., 1996. Infection 24:187-9). This may be because adult I. persulcatus are more important than nymphs as vectors; they carry a greater spirochaetes load than do I. ricinus nymphs, a higher proportion of them are infected, and a greater proportion of them carry spirochaetes in the salivary glands, which would reduce the effectiveness of early removal of ticks as a preventive measure.

Vaccination
The difficulties presented by both the diagnosis and treatment of Lyme borreliosis have emphasised the value of preventive measures and considerable interest has therefore been shown in the possibility of developing safe and effective vaccines. The first vaccine available was for use in dogs and consists of a whole cell, chemically inactivated, preparation of B. burgdorferi spirochaetes formulated with a polymer-based adjuvant. Vaccines of this nature are on the market in both Europe and the USA. There is no prospect of a similar vaccine being adopted for use in humans because of concerns that a whole-cell vaccine would induce immunopathology through cross-reaction with human antigens.
For human vaccination, interest has focused on several highly immunogenic outer surface proteins (OspA, B, C), and the most intensively studied of these is OspA. It has been shown that the immunisation of laboratory mice with this protein protects against both syringe and tick-transmitted challenges, and it has also been shown that infected ticks feeding on immunised mice lose their infections. This suggests that such a vaccine may have a dual mode of action against the spirochaete, firstly in the tick shortly before transmission and secondly in the host shortly after transmission (Wormser GP. Clin Infect Dis. 1995 21:1267-74).
An OspA-based vaccine (LYMErix, Smithkline Beecham) for human use was available in the USA. However, the vaccine was withdrawn from the market early in 2002 because of poor commercial performance.

Pfizer and Valneva are investigating a new OspA-based vaccine, currently in phase 3 (https://www.pfizer.com/news/press-release/press-release-detail/phase-3-valor-lyme-disease-trial-valneva-and-pfizer). This vaccine is based on a 6-valent OspA-based Lyme borreliosis vaccine candidate.