vaccine

(vax-zine)

A substance that contains antigenic components from an infectious organism. By stimulating an immune response (but not disease), it protects against subsequent infection by that organism, or may direct an immune response against an established infection or cancer.

vertical transmission

Transmission, for example of HIV, from mother-to-baby.

viraemia

(vy-ree-me-uh)

The presence of virus in the blood.

viral load

Measurement of the amount of virus in a sample. HIV viral load indicates the extent to which HIV is reproducing in the body.

virion

(vi-ree-on)

A virus particle existing freely outside a host cell.

virologic response

The effect of treatment on viral load.

virological relapse

When viral load can be measured after previously being undectectable.

virulence

The power of bacteria or viruses to cause a disease. Different strains of the same micro-organism can vary in virulence.

virus

(vy-russ)

A microscopic germ which reproduces within the living cells of the organism it infects.

visceral

(viss-sir-ull)

Of or pertaining to the internal organs.

vulva

The external female genitals.