An old form of vaccine against tuberculosis has shown promise in people with HIV, researchers from Dartmouth Medical School and the National Public Health Institute of Finland report in the November 7th issue of the journal AIDS.
The vaccine is based on inactivated mycobacteria, a method of vaccination demonstrated to prevent tuberculosis in humans and animals prior to the introduction of the live TB vaccine known as BCG in the 1950s.
However, BCG is not effective in preventing the development of tuberculosis in people with HIV, so researchers decided to test the old method of vaccination to see if it could protect HIV-positive people.
The study was done in Finland where BCG vaccine is routinely administered at birth. A cohort of 39 HIV patients, mainly men, were divided into two groups to receive a five-dose course of the killed vaccine, Mycobacterium vaccae, or a control vaccine for Hepatitis B. Parallel studies were also conducted on HIV- negative subjects.
"The multiple-dose course of the inactivated vaccine boosted immunity against TB both in those with HIV and those without TB," said Dr C. Fordham von Reyn of Dartmouth Medical School in the USA. "The vaccine was also safe and did not adversely affect the patients' underlying HIV infection."
The researchers looked for mycobacteria-specific cellular immune responses in patients with CD4 cell counts above 200 cells/mm3 (median CD4 cell count 12 months after immunisation was 682 cells/mm3 in the M.vaccae recipients).
The study served as the basis for a large-scale trial Dartmouth researchers have been conducting since 2001 in Dar es Salaam, Tanzania with Muhimbili Hospital Medical Center. The five-year $3 million NIH funded study is the only efficacy trial of a new TB vaccine currently under way in the world. The Tanzania trial will enroll more than 2000 HIV-infected patients to determine if the boosted immunity detected in the Finnish study actually reduces the risk of tuberculosis among HIV infected people in Tanzania at high risk of the disease.
Further information on this website
Resources on TB at this website
Reference
Vuola JM et al. Immunogenicity of an inactivated mycobacterial vaccine for the prevention of HIV-associated tuberculosis: a randomized controlled trial. AIDS 17: 2351-2355, 2003.