Multicenter efficacy trial of a prophylactic recombinant Borrelia burgdorferi (Bb) Outer Surface Protein A (OspA) vaccine for Lyme Disease (LD)

Lyme disease is a multi-system inflammatory disease caused by Borrelia burgdorferi, an organism that expresses OspA. Sera-protection studies in animals showed that anti-OspA protected against challenge with Bb. The OspA vacdne is an E. coli expressed lipoprotein that induces an immune response in both animals and humans; and is well tolerated. This randomized, double-blind, placebo-controlled OspA trial enrolled 10,3% subjects, 18-92 y.o., from 14 U.S. centers in endemic areas. Recipients received 2 doses, 1 mo apart, of 30 mcg OspA or saline in the spring (1994) and 7518 received a 3^rd dose in 1995 (spring) (0,1,12 mo schedule). Subjects were observed thru two Lyme seasons for clinical and lab evidence of LD. Efficacy and safety were evaluated by an independent DSMB. Definite cases of LD had positive Lyme disease serology (IgG or IgM Western blot) and either (1) Acute undisseminated (Erythema migrans [EM]),(2) Acute disseminated (EM, carditis or nervous system involvement ), or (3) late Lyme disease (musculoskeletal or nervous system disease). Vaccine efficacy in adults ≤ 59 y.o. after 2 or 3 doses was 82% and 100% respectively. Efficacy was not demonstrated in subjects ≥ 60 y.o. after 2 doses, but an efficacy rate of 75% was shown in the 1st year after the 3^rd dose. Subjects were evaluated at the time of vaccination and throughout the trial for adverse events (AE's) including any neurologic or rheumatologic AE's. The frequency of occurrence of the serious AE's was similar in both the vaccine and placebo groups. This Lyme vaccine showed good efficacy in adults 18-59 y.o. after 2 or 3 doses, and in those ≥ 60 y.o. after an additional 12 mo booster dose. The vaccine was generally well tolerated with an acceptable safety profile.