Breakthrough infection/PrEP failure		An HIV infection in a person fully adherent to PrEP
Combination prevention		Programmes that use a mix of biomedical, behavioural and structural interventions
FTC	Emtricitabine	An antiretroviral used in PrEP
OLE	Open label extension	Typically a follow-on of a placebo-controlled clinical trial, where all participants are given open-label study drug (both they and the investigators know the drug is active and not a placebo)
PrEP	Pre-exposure prophylaxis	The use of antiretroviral medications by HIV-uninfected individuals to prevent acquisition of HIV
Risk compensation		The adjustment of behaviour in response to perceived changes in risk, in the case of PrEP, protection causing people to increase sexual behaviour that may involve exposure to HIV.
Serodifferent partnership		One partner is infected with HIV and the other is not
Seroconcordant partnership		Both partners are infected with HIV, or both partners are uninfected
TasP	Treatment as Prevention	The public health strategy of treating HIV-infected individuals to reduce HIV incidence in the population
TDF	Tenofovir Disoproxil Fumarate	An antiretroviral used in PrEP
Waitlisted trial		Trial design where participants receive the intervention immediately or after a deferred period