An inactivated, whole cell mycobacterial vaccine could cut TB cases among HIV-positive Africans by almost two-fifths, suggests a new study. TB is the most common cause of death for Africans with HIV.
The placebo-controlled, double-blinded trial involved 2,013 Tanzanian patients with Bacille Calmette-Guerin scars and at least 200 CD4 cells/mm3. Participants were randomized either to receive five intradermal doses of M. vaccae (N=1,006) or placebo (N=1,007) and followed every three months for a median of 3.3 years. The primary endpoint was disseminated TB, with definite or probable TB as secondary endpoints.
The trial was terminated early because of the slow accrual of disseminated TB, and significant protection against definite TB. Hazards ratios were: disseminated TB 0.52 (95 percent confidence interval [CI] 0.21-1.34; seven cases in M. vaccae, 13 cases in placebo; log-rank P=0.16), definite TB 0.61 (95 percent CI 0.39-0.96; 33 cases M. vaccae, 52 cases placebo; P=0.03) and probable TB 1.17 (95 percent CI 0.76-1.80; 48 cases in M. vaccae, 40 cases placebo; P=0.46). The M. vaccae was well-tolerated, with no adverse effect on CD4 cell count or viral load and no increase in serious adverse events.
The number of confirmed TB cases was 39 percent lower in the vaccinated group compared with those who received a placebo, representing a "significant milestone," said lead author Professor Ford von Reyn.
The booster might be given to patients in poor countries as soon as they are diagnosed with HIV, especially where officials are struggling to place those infected on antiretroviral drugs, according to experts. A vaccine program could be cost-effective compared with earlier antiretroviral treatment - the alternative means to fight TB in HIV patients, said Alvaro Bermejo, executive director of the International HIV/AIDS Alliance.
"This is a very important finding - it is the first time we are going to have a vaccine which is influential in preventing opportunistic infections in HIV patients," Bermejo said. "TB is a massive problem. The reduction of 39 percent seen in Tanzania, although not fabulous, is a good result."
The full study, "Prevention of Tuberculosis in Bacille Calmette-Guerin-Primed, HIV-Infected Adults Boosted with an Inactivated Whole-Cell Mycobacterial Vaccine," was published ahead of print by AIDS (2010;doi:10.1097/QAD.obo13e328335of1b).
02/05/10
TANZANIA: Vaccine “Could Cut HIV TB Deaths”
Source: BBC (01.30.10); Courtesy of the CDC National Center for HIV, STD, and TB Prevention