Preliminary references are included below:


UK BHIVA and BASHH Guidelines for Adult HIV Testing (2020])

UK Guideline for the use of HIV Post-Exposure Prophylaxis (2021)

BHIVA/BASHH guidelines on the use of HIV pre-exposure prophylaxis (PrEP) (2018)

UK guidelines for the management of sexual and reproductive health of people living with HIV (2008)

US CDC. Information about HIV testing from the US CDC.

Swiss Statement (on reduced transmission with undetectable viral load): Vernazza P et al. Les personnes seropositives ne souff rant d’aucune autre MST et suivant un traitment antiretroviral efficie ne transmettent pas le VIH par voie sexuelle. Bull Med Suisses 2008; 89: 165–69.
English translation: (PDF)

HIV Transmission

Impact of treatment on reducing transmission


Attia S et al. Sexual transmission of HIV according to viral load and antiretroviral therapy: systematic review and meta-analysis. AIDS. 2009. 17; 23(11): 1397-404.

Castilla J et al. Effectiveness of highly active antiretroviral therapy in reducing heterosexual transmission of HIV. JAIDS 2005. 40(1): 96-101.

Cohen MS et al. HPTN 052 Study Team. Prevention of HIV-1 infection with early antiretroviral therapy. NEJM 2011. 365(6): 493-505.

Donnell D et al. The Partners in Prevention HSV/HIV Transmission Study Team. Heterosexual HIV-1 transmission after initiation of antiretroviral therapy: a prospective cohort analysis. Lancet. 2010; 375(9731): 2092-8.
Full text access:

Hughes J et al. Partners in Prevention HSV/HIV Transmission Study Team. Determinants of Per-act Infectivity of HIV-1 in the Partners in Prevention Study. CROI 2011, Boston, Abstract 135.

Rodger AJ et al for the PARTNER study group. Sexual activity without condoms and risk of HIV transmission in serodifferent couples when the HIV-positive partner is using suppressive antiretroviral therapy. JAMA, 2016;316(2):1-11. DOI: 10.1001/jama.2016.5148. (12 July 2016). Full free access.

Rodger AJ et al. Risk of HIV transmission through condomless sex in serodifferent gay couples with the HIV-positive partner taking suppressive antiretroviral therapy (PARTNER): final results of a multicentre, prospective, observational study. Lancet 2019; published online May 2. (Open access)

De Vincenzi I et al. A longitudinal study of HIV Transmission by heterosexual partners. N Engl J Med 1994; 331:341-346. DOI: 10.1056/NEJM199408113310601. (11 August 1994).

Viral load more important than gender:

Melo MG et al. Sexual transmission of HIV-1 among serodiscordant couples in Porto Alegre, southern Brazil. Sexually Transmitted Dis. 2008. 35(11): 912-5.

Reynolds SJ et al. HIV-1 transmission among HIV-1 discordant couples before and after the introduction of antiretroviral therapy. AIDS 2011. 25(4): 473-7.

Gay men:

Jin F et al. Per-contact probability of HIV transmission in homosexual men in Sydney in the era of HAART. AIDS 2010, 24(6): 907–91.

Baggaley RF et al. Infectiousness of HIV-infected homosexual men in the era of highly active antiretroviral therapy. AIDS 2010. 24(15): 2418-20.

Hallett TB et al. Estimating the risk of HIV transmission from homosexual men receiving treatment to their HIV-uninfected partners. Sexually Transmitted Infections. 2011; 87(1):17-21.

Sullivan PS et al. Estimating the proportion of HIV transmissions from main sex partners among men who have sex with men in five US cities. AIDS 23, 1153–1162 (2009).

Wilson DP et al. Infectiousness of HIV-infected men who have sex with men in the era of highly active antiretroviral therapy. AIDS 2010. 24; 24(15): 2420-1.

Case study where transmission occurred when viral load was undetectable (<50 copies/mL):

Stürmer M et al. Is transmission of HIV-1 in non-viraemic serodiscordant couples possible? Antivir Ther. 2008;13:729-732.


For PrEP references, including the iPrEX, PROUD and IPERGAY studies, please see this link from the i-Base UK Guide to PrEP (2021).


Hughes J et al. Partners in Prevention HSV/HIV Transmission Study Team. Determinants of Per-act Infectivity of HIV-1 in the Partners in Prevention Study. CROI 2011, Boston, Abstract 135.

Bailey RC et al. 2010. The protective effect of adult male circumcision against HIV acquisition is sustained for at least 54 months: results from the Kisumu, Kenya trial. XVIII International AIDS Conference, Vienna, July 18-23. Late breaker poster FRLBC101.

Auvert B et al. Impact of male circumcision on the female-to-male transmission of HIV. 3rd IAS Conference on HIV Pathogenesis and Treatment, Rio de Janeiro, 2005. Abstract TuOa0402.

McCoombe SG et al – How HIV enters the human penis. XV Intl AIDS Conference, Bangkok. Abstract MoPeA3048. See HIV Treatment Bulletin, August 2004. See HTB report:

Gray R et al. Keratinization of the adult male foreskin and implications for male circumcision. AIDS: 1 June 2010 – Volume 24 – Issue 9 – p 1381.

Minh D et al. HIV-1 female-to-male sexual transmission: evaluation of circumcised and uncircumcised penile tissue. 19th International AIDS Conference. 22-27 July 2012, Washington.  Oral Abstract MOLBA03.

Increased risk of HIV transmission from washing after sex

Makumbi FE et al. Male post-coital penile cleansing and the risk of HIV-acquisition in rural Rakai district, Uganda. Abstract WEAC1LB. (slides)

Makumbi FE et al. Postcoital penile washing and the risk of HIV acquisition in uncircumcised men. AIDS 2016. 30(10);1669–1673. doi: 10.1097/QAD.0000000000001097. (19 June 2016)

McClelland SR et al. Vaginal washing and increased risk of HIV-1 acquisition among African women: a 10-year prospective study. AIDS 2006, 20:269–273. See related HTB report:


De Vincenzi I et al. A longitudinal study of HIV Transmission by heterosexual partners. N Engl J Med 1994; 331:341-346. DOI: 10.1056/NEJM199408113310601. (11 August 1994).

Weller S, Davis K. Condom effectiveness in reducing heterosexual HIV transmission. Cochrane Database System Rev. 2002;(1): CD003255.

HIV transmission and oral sex

Hawkins DH et al. UK Department of Health. Report of a Working Group of the UK Chief Medical Officers’ Expert Advisory Group on AIDS. Review of the evidence on the risk of HIV transmission associated with oral sex.

Dillon B et al. Primary HIV infections associated with oral transmission. 7th Conference on Retroviruses and Opportunistic Infections, San Francisco, CA, Jan 30—Feb 2, 2000 (abstract 473).

Hawkins DA et al. Oral sex and HIV transmission. Sex Transm Infect 2001;77:307-308 doi:10.1136/sti.77.5.307.

Rothenberg RB et al. Oral transmission of HIV. AIDS. 1998 Nov 12;12(16):2095-105.

Schacker T et al. Clinical and epidemiologic features of primary HIV infection. Ann Intern Med 1996; 125: 257-264.

Peiperi L et al. HIV inSite. Risk of HIV Infection Through Receptive Oral Sex. UCSF roundtable discussion, 2003. HIV inSite.

Viral load in breast milk

Semba RD et al. Human immunodeficiency virus load in breast milk, mastitis, and mother-to‐child transmission of human immunodeficiency. J Infect Dis 1999; 180: 93-98.


McLaren PJ  et al. Evaluating the impact of functional genetic variation on HIV-1 control. The Journal of Infectious Diseases, jix470. Published: 09 September 2017. 


Most to be added.

(GUD acquisition associated with HIV and HIV associated with higher HSV viral load):

Serwadda D et al. HIV acquisition associated with genital ulcer disease and herpes simplex virus type 2 infection: a nested case-control study in Rakai, Uganda. J Infect Dis 2003;188:1492-7.

Vandepitte J et al. Prevalence and Correlates of Mycoplasma genitalium Infection Among Female Sex Workers in Kampala, Uganda. J Infect Dis. 2012 Jan;205(2):289-96. Epub 2011 Nov 18.

Hughes JP et al. Determinants of Per-Coital-Act HIV-1 Infectivity Among African HIV-1–Serodiscordant Couples. J Infect Dis. Volume 205, Issue 3 p. 358-365, Jan 2012.

Transmission and viral load

(Model suggesting heterosexual risk of 1% per exposure when semen viral load is 100,000 c/mL and 0.03% when semen viral load is 1,000 c/mL):

Chakraborty H et al. Viral burden in genital secretions determine male-to-female sexual transmission of HIV-1 a probabilistic empiric model. AIDS 15 621-627, 2001.

(Higher transmission during seroconversion and early infection):

Wawer MJ et al. Rates of HIV-1 transmission per coital act, by stage of HIV-1 infection, in Rakai, Uganda. J Infect Dis 2005;191:1403-9.

Hayes RJ et al. Amplified HIV Transmission during Early-Stage Infection: rates of transmission per coital act. JID Feb 15, 2006

Hollingsworth D et al. HIV-1 Transmission, by stage of infection. J Infect Dis. (2008) 198 (5): 687-693.

Boily M-C et al. Heterosexual risk of HIV-1 infection per sexual act: systematic review and meta-analysis of observational studies. Lancet Inf Dis 9(2)118-129. DOI: 10.1016/S1473-3099(09)70021-0. (February 2009).

Study reporting differences between viral load in blood compared to semen:

Lambert-Niclot S et al. Detection of HIV-1 RNA in seminal plasma samples from treated patients with undetectable HIV-1 RNA in blood plasma on a 2002-2011 survey. AIDS. Concise communication. POST ACCEPTANCE, 29 February 2012 doi: 10.1097/QAD.0b013e328352ae09

Number of exposures

(Interesting study in serodifferent heterosexual couples reporting a 10% risk after 10 or fewer contacts but only 23% risk after 2,000 contacts. This highlights that people more susceptible to catching HIV will need very few exposures but that other reasons are not quickly overcome by number of exposures):

Downs AM et al. Probability of heterosexual transmission of HIV: relationship to the number of unprotected sexual contacts. JAIDS Hum Retroviruses 1996 11 388-395

(Technical but interesting study looking at models for the relative importance of the number of partners vs the number of sex acts):

Kaplan EH. Modelling HIV infectivity: Must sex acts be counted?” JAIDS Hum Retroviruses 1990 3 55-61.

(Risk related to HIV prevalence, particularly for gay men in the UK):

White PJ et al. Is HIV out of control in the UK? An example of analysing patterns of HIV spreading using incidence-to-prevalence ratio? AIDS. 2006 Sep 11; 20(14):1898-901

HIV tests and testing

HPA Midas test reports (for results on individual manufacturers tests):

Branson B. The Future of HIV Testing. JAIDS Journal of Acquired Immune Deficiency Syndromes: 15 December 2010 – Volume 55 – Issue – pp S102-S105

(Study describing how a 4th generation Ag/AB test is evaluated and the impact on recuing the testing window compared to a third generation antibody only test):

Sickinger E et al. Multicenter Evaluation of a New, Automated Enzyme-Linked Immunoassay for Detection of Human Immunodeficiency Virus-Specific Antibodies and Antigen. Journal of Clinical Microbiology, Jan. 2004, p. 21–29 Vol. 42, No. 1 0095-1137/04.

(4th vs 3rd generation tests):

Van Binsbergen J et al. Improved performance of Seroconversion with a 4th generation HIV Antigen/Antibody assay. Journal of Virological Methods 82 (1999) 77–84.

Window period after exposure for viral load and antibody responses

Busch MP et al. Time course of viremia and antibody Seroconversion following human immunodeficiency virus exposure. American Journal of Medicine 1997; 102:117-124.

Feibig EW et al. Dynamics of HIV viremia and antibody seroconversion in plasma donors: implications for diagnosis and staging of primary HIV infection. AIDS: 5 September 2003 – Volume 17 – Issue 13 – pp 1871-1879

(Early study – using early tests – reporting 95% of seroconversion within 6 months):

Horsburgh CR Jr et al. Duration of human immunodeficiency virus infection before detection of antibody. Lancet 1989; 2: 637-40.

Lindback S et al. Viral dynamics of primary HIV-1 infection and duration of follow-up after HIV exposure. Karolinska Institute Primary HIV Infection Study Group. AIDS. 2000 Oct 20;14(15):2333-9, 22)

Reimer L et al. Absence of detectable antibody in a patient infected with human immunodeficiency virus. Clinical Infect Dis. 1997 Jul; 25(1): 98-100.

FDA letter for viral load to be used “as an aid” to diagnose HIV in acute or early infection. 04 October 2006.

(Review of rare cases where people test HIV antibody negative but whose symptoms are confirmed to be HIV-related by a positive PCR viral load test):

Spivak AM et al. Seronegative HIV-1 infection: a review of the literature. AIDS: 19 June 2010 – Volume 24 – Issue 10 – p 1407–1414.

Interpreting risk, popular medicine reporting and statistics

Gardner D. Risk: The Science and Politics of Fear. Virgin Books, 2009.

Goldacre D. Bad Science. Fourth Estate, 2008.

Petri A and Sabin C. Medical Statistics at a Glance. Wiley-Blackwell, 3rd edition,  2009.

Last updated: 1 June 2021.