Lyme Disease Vaccine—Reply

In Reply: Drs Schofield and Parenti point out that there was no statistically significant difference in the incidence of new arthritis diagnoses between the placebo and vaccine groups during the 20 months of follow-up in 1 study of outer-surface protein A (OspA) vaccine with adjuvant.¹ However, reservations were expressed by members of the US Food and Drug Administration advisory committee regarding the relatively brief follow-up periods, particularly with regard to the development of late manifestations of Lyme disease, such as arthritis.^2- 3 One month after the publication of the vaccine trial results, Gross et al⁴ identified an autoantigen that was cross-reactive with OspA. The authors hypothesized that OspA-primed T cells in synovial fluid might remain activated by stimulation from the cross-reacting peptide, even after adequate treatment with antibiotics. Continued surveillance of vaccine recipients for development of arthritis appears prudent.