Even people with HIV who take antiretroviral drugs but still have some virus particles in their blood (less than 1,000 particles per milliliter) can hardly transmit the virus through sex. That limit is higher than previously thought, points out an analysis of existing studies that appeared in the medical-scientific journal on Saturday The Lancet. Previously, practitioners maintained a limit of 200 virus particles per milliliter of blood. With the publication of the new insights, the World Health Organization (WHO) has published a new policy document with adjusted advice.
The human immunodeficiency virus (HIV) can cause AIDS. Someone can contract it through contact with infected blood, for example through needles, or through unprotected sex with someone who carries the virus. Once infected, people never get rid of the virus.
People living with HIV can use daily antiretroviral therapy (ART) to suppress the amount of virus in their blood to such an extent that it can no longer be measured in the blood. Then they will not get sick and they will no longer be able to transmit the virus. But sometimes the virus remains in low quantities. Previous studies have shown that below 200 virus particles per milliliter of blood, the risk of transmission through sex is nil. Now it appears that that limit may be higher.
Transfer to partner
The new study pooled data from eight existing studies, totaling more than 7,700 male-male or female-male couples from 25 countries in which one partner has HIV and the other does not. The studies ran from 4 to 26 years. Of the 323 times the virus was passed on to the partner through sex, only two cases occurred in a person with HIV with less than 1,000 virus particles per milliliter of blood. In both cases, the blood had been tested about 50 days before the partner contracted the virus, so it is possible that the number of particles was higher at the time of transmission. The vast majority of infections, more than 80 percent, occurred in a partner with more than 10,000 virus particles per milliliter of blood.
The researchers conclude that the risk of transmitting the virus to a sexual partner is almost zero if the amount of virus measured in the blood is less than 1,000 parts per milliliter.
Without ART, the amount of HIV particles in the blood can reach 30,000 or even 500,000 per milliliter, depending on the stage of the infection.
Sensitive laboratory tests to measure HIV are not widely available in many countries. The new findings show that simpler tests using blood from a finger prick are also sufficient. It can also reliably indicate whether the amount of HIV is below 1,000 particles per milliliter.
Stretch the message
The results support the maxim that is used worldwide, and also in the Netherlands: U=U (undetectable = untransmittable; undetectable = not contagious), says Maria Prins of the GGD Amsterdam, also professor of public health and epidemiology of infectious diseases at the Amsterdam UMC. “If that lower limit can now go to 1,000 parts per milliliter, that will stretch that message a bit. People with HIV may be afraid of infecting their partner, this could reduce that fear.”
The GGD Amsterdam will, in consultation with all relevant authorities in the city, examine how they will use the new information, says Prins. In the Netherlands, all people with HIV receive ART and their blood is tested every six months. In the unlikely event that virus is measured, practitioners look at how this can be brought back to an unmeasurable value, and the advice for sex partners without HIV is to use condoms or take PrEP, a drug that prevents HIV infection.
The results of the study can motivate people with HIV to continue to take antiviral drugs faithfully. In addition, they help to reduce the stigma that surrounds people living with HIV in many countries.
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