The following is a summary of “Optimisation of dose level and vaccination schedule for the VLA15 Lyme borreliosis vaccine candidate among healthy adults: two randomised, observer-blind, placebo-controlled, multicentre, phase 2 studies,” published in the May 2024 issue of Infectious Disease by Bezay et al.

Researchers conducted a retrospective study optimizing the dose and schedule for VLA15, a Lyme disease vaccine targeting key outer surface protein A (OspA) strains.

They involved adults aged 18-65, excluding recent Lyme borreliosis or tick bites, participated. Study 1 occurred at 9 locations (6 in the USA, 2 in Germany, 1 in Belgium), and study 2 was at 5 US sites from study 1. Participants received VLA15 vaccine or placebo (90 μg in study 1, otherwise 135 μg or 180 μg) via varied injections. The 90 μg dose in study 1 was halted in the initial safety phase per the Data Safety Monitoring Board advice. Randomization in study 1 included site, age group, and B burgdorferi  (serostatus). Antibody levels against Lyme disease were measured post-vaccination, focusing on compliant participants. Safety was assessed in all vaccinated individuals.

The result showed in study 1 a total of 573 participants were screened of which 29 received 90 μg VLA15, 215 got 135 μg, 205 got 180 μg, and 124 got placebo. The OspA-specific IgG GMTs at 3 months ranged from 74·3 to 308·6 units per mL across different doses. In study two, 248 participants were screened, with 97 receiving 135 μg VLA15, 100 receiving 180 μg, and 51 receiving placebo. The GMTs at month 7 ranged from 278·5 to 596·8 units per mL for active doses. Local AEs were observed in both studies, with higher rates after vaccination compared to placebo. The unsolicited AEs were also reported in study one, 52%(48–57) of participants in VLA15 and 52% (43–60) in placebo groups. Study two rates were 65% (58–71)for VLA15 and 69% (55–80) for placebo. Serious adverse events were rare: study one, 2% (1–4); study two, 4% (2–7). Special interest events showed study one at 1% (0–2); study two at 1% (0–3), with one AE in ventricular extrasystoles with no other AEs or deaths reported.

Investigators concluded that a 180 μg dose of VLA15 at 0, 2, and 6 months proved safe, well-tolerated, and induced strong immune responses to all Lyme disease strains targeted by the vaccine, warranting further development.

Source: thelancet.com/journals/laninf/article/PIIS1473-3099(24)00175-0/abstract#%20