Glossary

study population – the group of people in a study.

immune system – the system that your body uses to fight infections.

MSM – men who have sex with men.

mL (millilitre) – a measure of a volume of liquid. 1000 millititres = 1 litre.

lumbar puncture – taking a sample of spinal fluid by inserting a needle into the body at the base of the spine. Also called a spinal tap.