Elderly may not benefit from new vaccines.

• Position: Tuberculosis

Elderly people might not benefit from some of the tuberculosis vaccines currently in development, suggests research in Mechanisms of Ageing and Development. Some vaccines under study are designed to activate a specific molecule that is an early participant in the immune response against TB in young people. The study suggests that, in older persons, this molecule remains relatively inactive, even in the face of TB infection.

The presence of this molecule, called a toll-like receptor, is not required in older individuals to generate an immune response to Mycobacterium tuberculosis, the pathogen that causes TB infection. The immune response in youngsters without the receptor, however, is not robust enough to fight TB infection adequately. So, while young people would stand to benefit from a vaccine that boosts the molecule's function, it appears a new direction in vaccine research is needed to ensure that the elderly also receive protection against the disease.

One caveat, maintains internist Joanne Turner, lead author of the paper, is that this finding occurred in those who completely are lacking the receptor in question. "If [older individuals] have this receptor on the surface of their cells, it probably functions, but not as well as it should, and...