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Question on U = U


In a recent post in the "How Can I Prevent HIV?" part of the forums (where I can't respond), Jim Allen says..

--- Quote ---Sure, You could still pass on HIV by Injecting drugs (Sharing syringes), giving blood transfusions and through organ donations.
--- End quote ---

I'm a bit confused and not sure how sharing syringes with an undetectable viral load can transmit HIV.. since it is through blood test that determine an undetectable status.
But U=U in sex, even though semen or vaginal fluids isn't being tested for HIV? How come?

Could someone please explain this? Not trying to be a wise ass, just want to understand the science on this.

Jim Allen:
Updated my post, as I had the time to type it out at home.

There is more than two decades of TaSP evidence in terms of sexual transmission to support the U=U statement and studies showing the blood and sexual fluid viral load correlation. However these can take longer to be UD, hence in part, the U=U and the Swiss Statement in 2008 message included being UD in blood levels 6+ months first.

Vernazza P et al. Bulletin des médecins suisses 89 (5), 30 January 2008

Sexually even with detectable levels HIV there are several barriers/defences HIV must overcome to cause infection and with a low viral load it does not.  More info on these barriers: Barriers to mucosal transmission of immunodeficiency viruses

I belive the lowest ever recorded transmission was from an individual not on treatment, with a blood plasma viral load of 362. I would have to look around for that reference as I think it was in 2000.

Other vectors like IUD and Blood transfusions there is insufficient TaSP research to call it zero risk, and some of these vectors lack some of the natural barriers found in sexual transmission.  So the question remains if directly injecting a quantity of blood into someone's bloodstream with a viral count of 200 could cause infection.

TaSP - Summary of evidence going back to 1998

U=U Statement

Loutfy MR, Wu W, Letchumanan M, Bondy L, Antoniou T, Margolese S et al. Systematic review of HIV transmission between heterosexual serodiscordant couples where the HIV-positive partner is fully sup-pressed on antiretroviral therapy. PLoS One 2013;8(2):e55747.

Cohen MS, Chen YQ, McCauley M, Gamble T, Hosseinipour MC, Ku-marasamy N et al. Prevention of HIV-1 infection with early antiretro-viral therapy. The New England Journal of Medicine 2011;365(6):493-505.

Vernazza P, Hirschel B, Bernasconi E, Flepp M. Les personnes sero-positives ne souff rant d’aucune autre MST et suivant un traitment antiretroviral effi cie ne transmet-tent pas le VIH par voie sexuelle. Bulletin des Medecins Suisses 2008;(89):165-9.

Injecting drug use & transfusions.

2019 - Undetectable does not equal untransmittable for HIV and blood transfusion (abstract)

A low concentration of virus that is too low to transmit sexually may still be able to be transmitted by blood components when the greater volume in transfusion is taken into account. As a result, there is the potential for confusion for prospective donors in terms of their HIV transmission risk.

People who inject drugs: We do not yet have enough data to know whether ART resulting in a suppressed HIV viral load prevents HIV transmission with the sharing of injection drug equipment; in the trials mentioned above, only 2% or fewer of participants reported injection drug use.(**) We recommend consistent use of clean injection equipment for people who inject drugs (PWID), and PrEP for HIV-negative PWID for whom this is not possible, as well as for those who remain at risk of HIV through sexual transmission.

HIV antiretroviral therapy and prevention use in US blood donors: a new blood safety concern

Persons who are HIV positive and taking ART and persons taking PrEP to prevent HIV infection are donating blood. Both situations could lead to increased risk of HIV transfusion transmission if blood screening assays are unable to detect HIV in donations from infected donors.

Jim - There is some evidence that with ART usage HIV rates under people Injecting drugs is reducing. However, is not conclusive and hard to directly correlate:

Fraser H, Mukandavire C, Martin NK, et al. HIV treatment as prevention among people who inject drugs – a re-evaluation of the evidence. International Journal of Epidemiology. 2017 Apr 1;46(2):466–478.

Kirk G, Galai N, Astemborski J, et al. Decline in community viral load strongly associated with declining HIV incidence among IDU: In: Proceedings of the 18th conference on Retroviruses and Opportunistic Infections; 27 Feb to 2 March 2011, Boston, MA, USA; 2011.

Thank you very much Jim, I appreciate the links and you taking the time to explain it to me.. this has really cleared up many questions I had.. especially about the barriers HIV has to go through during sex.

And I agree more research is needed on undetectable blood to  negative blood transmission or lack of transmission?.

Just thinking that even HIV positive women have successfully given birth to HIV negative babies while on effective treatment, don't these woman share the same blood with their babies?.. so it gets one thinking maybe U=U regardless of the pathway.

Jim Allen:
You're welcome.

U=U regardless of the vector is not there yet and might never be looking at some of the evidence. Yes, some of the vectors need more far more study to understand TaSP reduces the risk or if the threshold might be lower than the 200 and 6 months set for sexual transmission.

As for childbirth, the risk is not zero but getting close to it with the correct steps. Although, again there are different barriers again at work and some HIV drugs that cross to the placenta offering what is believed to be a PEP effect. These barriers are something that other vectors like transfusions and drug users don't have. The breastfeeding afterwards is still a debate.

Why U=U Does Not Cover Breastfeeding


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