Inactivated vaccines have better safety profiles than live vaccines in HIV positive subjects, and previous research has shown that immunological responses to non-tuberculous mycobacteria provide protection against tuberculosis (TB).

This study compared the response of both HIV positive (n = 39) and HIV negative (n = 10) individuals with prior BCG immunisation to five doses of heat inactivated Mycobacterium vaccae (MV) vaccine with a control. Lymphocyte proliferation (LPA) and interferon gamma (IFN-γ) responses to MV and Mycobacterium tuberculosis (MTB) antigens were measured at intervals before, during, and after the course. The immune response to MV increased significantly after immunisation and was still evident at >1 year. There was a less significant response to MTB antigen in HIV positive subjects. No significant change was seen in the CD4 cell counts or viral loads of HIV positive patients before and after immunisation. There were no major adverse effects.

Inactivated MV vaccine appears to boost BCG primed immunity in HIV positive individuals which may provide protection against the development of active TB. Further large scale trials of the efficacy of this regimen are currently in progress.