As reasonable as the question may seem, there are potential consequences, even among monogamous couples. Chief among these is reinfection.
As a communicable virus, HIV has the ability to mutate as it is exposed to different drugs. If a partner is not very adherent to taking their HIV drugs, then the virus can mutate and become resistant over time to that class of drugs.
As such, it is possible that one partner can infect the other with an entirely different variant of the virus and, by doing so, transmit the resistance along with the virus.
While this is less likely to happen if both partners are on antiretroviral therapy, there is still a chance if one or the other partner, for any reason, does not have a suppressed viral load (i.e. viral load < 200 for more than 6 months). If this is the case, the acquired resistance can cause your drugs to work less effectively or even fail.
Understanding HIV Drug Resistance
HIV is not one type of virus. It is comprised of a multitude of different strains and variants. Moreover, if you are living with HIV, you are likely carrying more than one variant. Your genetic pool may have tens of thousands of different variants, some of which are more resistant than others.
If a person has poor adherence to treatment, the virus pool can continue to develop mutations to new drugs they are prescribed. Over time, this can result in treatment failure and the loss of ever being effectively treated with that class of drugs again. When the drugs are no longer able to stop the resistant viruses from multiplying, treatment failure occurs.
Sometimes superinfection can occur. This when a person with HIV gets another HIV type or strain. In rare cases, the superinfection cannot be treated by any of the current available antiHIV medications.
Preventing Reinfection
In a relationship, if you’re not sure if your partner has sustained viral suppression, then consistent condom use should be the rule. While condoms are not 100% foolproof, they remain the best first-line defense against HIV.
If reinfection occurs, you may not even know it. Some people may develop mild, flu-like symptoms, while others will only know there is a problem when their viral load suddenly shoots up.
If treatment failure is declared, you will be given genetic tests to assess which drugs you are resistant to and to determine the combinations of drugs best suited for your virus. With improved adherence to therapy and avoidance of reinfection, there is no reason your HIV drugs shouldn’t last a decade or more.
