Experiences of undetectable = untransmittable among couples with different HIV serostatus: a qualitative study in Tanzania and Uganda

Abstract

Background

HIV serodifferent couples where one partner is living with HIV and the other is not, remain a key population for HIV prevention. Maintaining an undetectable viral load eliminates the risk of sexual HIV transmission, this principle is often summarised as undetectable = untransmittable (U = U). However, the extent to which this principle is understood and utilised by serodifferent couples remains unclear. This study aimed to explore both partners’ perceptions, experiences and adoption of U = U within their relationships.

Methods

We conducted an exploratory qualitative study using in-depth interviews with 20 serodifferent couples (40 participants) between July and August 2023 in Ifakara, Tanzania and Kasangati, Uganda. Each partner was interviewed separately. Interviews explored: (1) Awareness of U = U, (2) Lived experiences related to U = U, and (3) Social perceptions of U = U and HIV serodifference. The interviews were audio-recorded, transcribed, and analysed using thematic analysis with Atlas.ti for coding.

Results

All participants were in a heterosexual serodifferent relationship and had mutually disclosed their status. The average age was 25 years, and couples had been partnered for approximately 3.5 years. All 40 participants (100%) had basic knowledge of U = U or treatment as prevention. The qualitative analysis identified four key themes that were broadly consistent in both settings: (1) Knowledge of U = U facilitated adoption, with initial doubts giving way to trust over time as partners remained HIV-negative; (2) Disclosure triggered emotional responses, which were alleviated through counselling, with U = U influencing relationship confidence and fertility decisions; (3) Use of additional prevention (PrEP, condoms) reinforced trust in U = U, addressing residual concerns about adherence and fidelity; (4) Persistent stigma and limited community awareness constrained U = U’s potential impact. Themes were largely consistent across Uganda and Tanzania, though Ugandan participants more frequently reported detailed provider counselling and PrEP use.

Conclusion

This study highlights how understanding experiences of U = U among HIV serodifferent couples in Tanzania and Uganda are shaped by personal, relational, and contextual factors. Our findings suggest that U = U communication strategies should be strengthened through context-specific counselling, improved access to viral load testing, and community education. Further research is needed to explore how U = U is perceived and adopted in more diverse settings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-025-24120-1.

Introduction

Globally, about 39.9 million people were living with HIV (PLWH) in 2023, with sub-Saharan Africa (SSA) accounting for the majority of people living with HIV (PLWH) and new acquisitions [1, 2]. Uganda and Tanzania have made progress toward achieving the Joint United Nations Programme on HIV/AIDS (UNAIDS) 95–95–95 targets; however, important gaps remain. In Tanzania, 82.7% of PLWH were aware of their status, 97.9% of those diagnosed were on antiretroviral therapy (ART), and 94.3% of those on treatment achieved viral suppression in 2023 [3]. Similarly, in Uganda, 90% of PLWH were aware of their status, 94% were on ART, and 94% achieved viral suppression in 2022 [4]. Both countries fall short of the first and last targets. Thus, PLWH with undiagnosed HIV could transmit HIV and undermine prevention efforts. Without diagnosis, PLWH cannot initiate treatment or achieve viral suppression—steps that are important to reducing HIV transmission and realising the benefits of treatment as prevention. HIV serodifferent couples where one partner is living with HIV and the other is not, represent a key population for HIV prevention in SSA. Serodifferent couples account for approximately 30% of new infections in the region and are often in stable, long-term relationships [5–7]. Evidence from randomised controlled trials and cohort studies demonstrates that sustained viral suppression eliminates sexual transmission of HIV within these relationships [8–12]. This message is widely referred to as “Undetectable equals Untransmittable” (U = U) [12].

U = U messaging is now endorsed globally by organisations such as UNAIDS and has been adopted into national HIV guidelines in over 100 countries, including Uganda and Tanzania [13–17]. Research from both low- and middle-income countries (LMICs) and high-income countries (HICs), shows that U = U knowledge is associated with improved overall health outcomes, a sense of normalcy and resilience among serodifferent couples, reduced stigma and increased engagement with HIV care among both people without HIV and PLWH [18–23]. However, gaps remain where limited viral load monitoring, stigma, and inconsistent provider communication undermine U = U’s potential impact [18, 24–29]. In SSA, there is growing awareness of U = U, but lack of understanding remains high. Studies in Kenya, Rwanda and South Africa revealed variable provider confidence in U = U counselling, and persistent community misconceptions remain barriers to effective uptake [25–27, 30]. Despite endorsements, HIV guidelines for Tanzania and Uganda [14, 17] do not include strategic communication or implementation of U = U, contributing to inconsistent messaging and poor patient-provider engagement. Consequently, many PLWH may miss out on the potential benefits of U = U.

When communicated clearly and understood correctly, U = U can positively impact relationship dynamics, resilience, sexual decision-making, fertility considerations, confidence in the relationship, and intimacy [18, 19, 21]. Yet, there is limited understanding of how both partners within a serodifferent couple comprehend and utilise U = U in their daily lives in SSA. To address this gap, our study aimed to assess the awareness, perceptions, and lived experiences of serodifferent couples regarding U = U in Tanzania and Uganda.

Methods

Study design

We conducted an exploratory qualitative study using in-depth interviews (IDIs) with serodifferent couples from July to August 2023.

Study setting

Participants were recruited from two high-volume HIV healthcare facilities in Ifakara, Tanzania and Kasangati, Uganda. In Tanzania, recruitment took place at the Chronic Diseases Clinic of Ifakara (CDCI), a specialised HIV and tuberculosis treatment facility located at the St. Francis Regional Referral Hospital in rural southern Tanzania. The clinic serves the Kilombero and Ulanga districts (population ~ 700,000) and collaborates with the Ifakara Health Institute, the Swiss Tropical and Public Health Institute, and the University Hospital Basel. Our sample was drawn from the Kilombero and Ulanga Antiretroviral Cohort, which currently has approximately 13,000 PLWH enrolled, with about 3,800 in active follow-up [31]. In Uganda, participants were recruited from Kasangati Health Center IV, a peri-urban public healthcare facility in Wakiso District, Central Uganda. Wakiso district (population ~ 3 million) [32] is in Central Uganda and has a HIV prevalence of 8.1% compared to the national adult prevalence of 5.8% [4]. The facility is supported by Makerere University Infectious Diseases Institute - an implementing partner for the U.S. President’s Emergency Plan for AIDS Relief and provides care for approximately 5,000 PLWH [33].

Study population and eligibility

We enrolled participants who were: [1] 18 years or older [2], in a serodifferent relationship with mutual HIV status disclosure [3], on ART for at least six months for the partner living with HIV, and [4] willing to provide informed consent.

Sampling

We used purposive sampling to recruit couples meeting the above criteria. Sample size was guided by thematic saturation and cross-site qualitative research standards [34], with 20 couples (40 interviews) targeted to identify cross-cultural themes.

Recruitment

Clinic records identified PLWH whose partner tested HIV-negative between January 2021 and January 2023. Clinic expert clients (i.e., PLWH who share their experiences to offer peer support), assisted in identifying potential couples from each clinic. The partners living with HIV were informed about the study and requested to invite their spouses to participate. Non-respondent partners were not included in the recruitment process. Research assistants (RAs) contacted interested couples by phone or in person. Informed consent was obtained from all participants. Upon mutual agreement of time and location, appointments for in-depth interviews were arranged. All participants were reimbursed per local Institutional Review Board guidance for their travel and time.

Data collection

We conducted 40 interviews with 20 HIV serodifferent couples, ten couples at each study site, using the developed semi-structured interview guide. Each partner in the couple participated in a single in-depth face-to-face interview. Before conducting the study, the interview guides were pilot-tested with four expert clients (two from Uganda and two from Tanzania) who closely mirrored the characteristics of the study population. The pilot interviews assessed clarity and cultural relevance and estimated an average completion time. Feedback from these pilot sessions led to minor revisions in wording and addition of context-appropriate probes. The final tool was translated into the local languages (Luganda for Wakiso and Kiswahili for Kilombero/Ulanga). Interviews were conducted in the language most comfortable for the participants: Kiswahili in Tanzania and English or Luganda in Uganda.

Quality control of transcriptions

All interviews were audio-recorded and transcribed verbatim. Translations were conducted by bilingual team members, interviews conducted in Kiswahili or Luganda were translated into English by bilingual team members, and a subset of transcripts was back-translated for accuracy. A shared codebook was developed and refined collaboratively. One analyst coded remaining transcripts, with periodic review by a second coder. An audit trail documented key decisions throughout the analysis.

One female RA (author L.S.), a trained counsellor and public health expert in Tanzania, conducted the IDIs. In Uganda, two female RAs (authors A.N. and B.K.) and one male RA (V.K.), all experienced and skilled in qualitative methods, collected the data and completed the analysis for both sites. The RAs were actively involved in crafting the interview guide and underwent a week-long training to familiarise themselves with the study protocol and interview guide. To eliminate bias, there was no interaction between participants and the rest of our authorship team; however, our team interacted with the collected data during analysis and manuscript preparation. Data were anonymised during transcription, and all identifiable information was omitted. The audio-recorded interviews were securely stored on a password-protected laptop. The translated and coded data were uploaded to a secure switch drive link accessible only to authorised personnel within the study team, who were identified and logged in the study file. No identifiable information is disclosed in any publication or conference activities related to the study.

Data analysis

A thematic analysis approach was used to analyse the data [35], guided by the Consolidated Criteria for Reporting Qualitative Research checklist, which was used to report the findings [36] (Additional file 3 in Supplementary materials). The interview transcripts were transcribed and translated, and the data were manually coded and categorised using Atlas.ti software (version 23) to streamline the coding process. To maintain consistency, three coders (A.N., B.K., and V.K.) collectively agreed upon a final coding scheme, which was then applied to all transcripts. In addition, two team members reviewed each transcript.

Results

Participant characteristics

Participant characteristics are summarised in Table 1. Saturation was obtained after interviewing 40 participants from the two sites. All 40 participants were in mutually disclosed heterosexual HIV serodifferent relationships. Female participants had a median age of 25 years (interquartile range [IQR], 20.5–33.5), while the median age for males was 25.5 years (IQR, 24–31.5). The median duration of their relationship was 3.5 years (IQR, 1.5–9.5). Most (60%) partners were living together, and four partners (10%) without HIV reported having other sexual partners outside this relationship, of whom three (75%) did not know the HIV serostatus. All 40 participants (100%) were aware of U = U or treatment as prevention.

Table 1.

Participant characteristics

Participants	Uganda (N = 20)	Tanzania (N = 20)	Total (N = 40)	%
Female	10	10	20	50.0%
Male	10	10	20	50.0%
Age (median)	24.5 (23,29.5)	26.5 (24, 39.5)	25 (23.5,31.5)
Years in relationship (median)	4.5 (3,7)	3 (1,15)	3.5 (1.5,9.5)
Living together (Yes)	6	18	24	60.0%
Other partners outside studya (Yes)	0	0	0	0%
Other partners outside studyb(Yes)	4	0	4	10.0%
Outside partner serostatus known (Yes)	3	0	3	75%
Outside partner serostatus known (No)	1	0	1	25%

^aPartner living with HIV

^bPartner without HIV

Qualitative results

We identified four key themes that captured participants’ experiences of U = U. First, knowledge and understanding of U = U facilitated its adoption. All participants recognised that consistent ART adherence led to viral suppression and therefore the virus cannot be passed sexually. However, they initially had doubts and scepticism about U = U which diminished over time when partners without HIV consistently tested negative. Second, disclosure of HIV status triggered a spectrum of emotions, which resolved after counselling and over time. U = U knowledge contributed to improved self-esteem, stronger relationship bonds, and informed fertility decisions. Third, having multiple prevention options (e.g., condoms and HIV pre-exposure prophylaxis (PrEP) facilitated the uptake of U = U and reduced anxiety about HIV transmission. Finally, multi-level stigma and lack of community awareness limited U = U benefits. Enacted stigma from partners was disempowering and stigma outside the partnership diminished their perceived quality of life. Themes were broadly consistent across Uganda and Tanzania, with couples in both setting.

Theme 1. Knowledge and lived experiences facilitated the adoption of U = U

Sources of U = U information

All participants were aware of U = U and most had received information about U = U from healthcare providers during their appointments or through outreach programs. One participant noted that healthcare workers sometimes conducted testing and counselling sessions at the local market. Another participant discovered U = U through online resources, while a third learned about it from a friend with comparable experiences. However, some participants recalled being informed by healthcare providers that U = U carried a low or minimal risk.

The counsellors tell us that when you adhere well to your drugs, the virus suppresses, which lowers the chances of getting other diseases and infecting anyone. Also, the drugs we take decrease the number of copies [of the virus] in the blood and reach an extent where the virus cannot be detected in the blood, although this does not mean you are cured of HIV. It simply means that the virus is not detected in the body. (Female PLWH, 30 years)

The health workers told us that many of us hide our status from our husbands, but when we adhere well to our drugs, we cannot infect our partners and unborn babies with HIV. (Female PLWH, 22 years)

Gradual trust in U = U through lived experience

mInitially, many participants had doubts and found it challenging to trust the U = U message fully. Most of the partners who were not living with HIV expressed initial skepticism about U = U, they felt a sense of betrayal but chose to remain in the relationship out of love, responsibility, or a desire to continue having children. This perspective shifted over time as they experienced repeated HIV-negative test results after being with their partner for an extended period. One partner without HIV initially struggled to accept the information about U = U discussed in counselling sessions. But with time, she began to find the information credible after several monthly tests confirmed that she did not have HIV.

I told my friend that I was not going to leave my wife, although she hurt me a lot when she did not disclose it to me yet we have a child already together, and she was also expecting another child. If we did not have a child together or if she was not pregnant, I would have told her to go back to her home. (Male without HIV, 24 years)

When I first heard it, I wondered, “How?” because I was having sexual relations with him every day, and here I was being told that when he takes the ARVs well, he will not infect me. I took long to believe it, and I think it was almost a whole year before I could believe it. I came to believe that I tested for one full year, and each time I would test, I would be HIV negative and I would test after every month, and I really got to be sure that I was HIV negative. I started believing that it was true that when he takes his ARVs well, he cannot infect me as the virus is ‘sleeping’ (dormant). (Female without HIV, 27 years)

Persistent uncertainties

Despite awareness, participants expressed nuanced concerns. These concerns encompassed beliefs that HIV strain diversity could pose a transmission risk despite viral suppression, occurrences of genital abrasions, sharing needles or sharp objects, instances of blood contact, and situations where the person living with HIV was not adherent to their medication or where the HIV-negative partner had other sexual relationships outside of their relationship. These issues underscored an underlying mistrust regarding potential transmission, revealing that real-life experiences occasionally challenged their confidence in U = U within the partnership.

When the partner with HIV has more than one sexual partner, even when she is virally suppressed, they can still transmit HIV to the negative partner because we all have different strains of HIV. The one I could be having could be different from what another person has, so if that person who has other sexual partners acquires HIV from another person, they might transmit that HIV to their negative partner. When you have wounds in your private parts, it is not advised to have live [condomless] sex with your partner since you can transmit HIV to your partner through those open wound wounds. Male partner without HIV, 24 years)

Yes, I have some doubts because the virus is still in the blood, and so the negative partner can get infected in case you both have wounds in your private parts and if you share blood, like using the same razor blades. I do not believe in using condoms for HIV prevention because I have a friend who was using condoms in order not to get pregnant but got pregnant, which means that HIV can also be spread even when you use condoms (Female PLWH, 27 years)

Theme 2. U = U and disclosure of HIV status

Post-disclosure

While all couples had mutually disclosed their HIV statuses, the timing, approach, and personal experiences surrounding the disclosure differed. Some participants reported that initial disclosure triggered fear, anxiety, feelings of diminished sexual desire and worry about relationship dissolution. Nonetheless, disclosure was viewed as a starting point that facilitated open communication, planning for children, and deeper trust.

I feared touching my girlfriend, and I could not imagine myself having sex with her. Even the mere thought of having sex with her made me feel like I had already contracted HIV. I could not even get the urge for sex with all the thoughts that were running in my mind. I never knew that I could ever have sex with my girlfriend, but never doubt the power of love and counselling. All that changed when the health worker told me that my girlfriend could not infect me with HIV when she [was] virally suppressed. (Male partner without HIV, 24 years)

The role of counselling

In both settings, couples described counselling and learning about U = U as instrumental in coping with disclosure and serodiscordance. Decisions regarding intimacy and childbearing were more informed and less fearful due to an understanding of the role of viral suppression in preventing transmission.

I had so many thoughts at that moment. The first thing that crossed my mind was that this relationship would not work. I got depressed. Our relationship was moving on well before I found out that she was HIV positive. I started fearing her [partner], and all I was thinking about at that time was leaving her because I did not see any reason to be in a relationship with someone who was HIV-positive… The only thing that revived my feelings for my girlfriend was the counselling that I got from Kasangati Health Centre. When we were told we could stay together, I knew there was a solution for me not to end the relationship. (Male partner without HIV, 24 years)

You know, accepting this was a bit challenging back then. I felt that within a month, there were still some issues. She still wanted to break up with me, but I continued to advise her. Even in terms of physical intimacy, it was very difficult. I made a lot of effort to comfort her. Even though I had my own fears about how I could live with someone with that condition, over time, as we continued attending the clinic and receiving counselling, we reached a point where we were okay with each other. (Male partner without HIV, 31 years)

“Regarding children, we discussed it and agreed that we want to have a child. We agreed on how to proceed with having a child, and since she’s in this situation, we sought advice at the clinic. They guided us on how to protect both of us.” (Male partner without HIV, 23 years).

Theme 3. Confidence in U = U

Having additional prevention supported U = U uptake

Participants indicated that they used alternative prevention methods, such as condoms, to mitigate the risk of HIV transmission when their adherence to ART was suboptimal. In these instances, the primary intention for using condoms was not to prevent pregnancy or sexually transmitted infections. Some individuals chose to utilise PrEP irrespective of their partner’s viral suppression status. The incorporation of additional prevention strategies led to reduced anxiety related to the acquisition of HIV. This theme appeared more strongly in Uganda, where PrEP access was more frequently mentioned.

“… I have not adhered well to my drugs. I feel like my partner cannot be safe when I have unprotected sex with him, so I asked him to use condoms.” (Female PLWH, 30 years).

“… I believe it works because I have been with my partner for ten [10] years, and I have never contracted HIV. If you follow the instructions of the health workers, it is very possible, and besides, I also adhered well to my PrEP.” (Male partner without HIV, 28 years).

Couples’ confidence in U = U

Was reinforced by having children and a spouse without HIV. PLWH, for their part, drew strength from their self-awareness and an understanding that regular adherence to ART would prevent transmission. For others, it was reinforced by the partner without HIV consistently testing negative over time. For some couples, this trust stemmed from a mutual understanding built through years of living together without seroconversion and a commitment to support the PLWH.

“From my own experience, my husband and I have been together for almost thirteen years now, and we have a healthy child together. So, I have 100% confidence that HIV treatment is very effective in preventing transmission.” (Female PLWH, 43 years).

“What I know is that I was very sure that I was going to give birth to children with HIV, but all my three [3] children are HIV-negative, and that made me believe that a positive mother can give birth to HIV-negative children as I did and that also made me believe that you cannot also infect the negative partner if you take your drugs well every day and on time when the virus sleeps [suppresses].” (Female PLWH, 26 years).

Theme 4. Multi-level stigma and lack of community awareness limited U = U benefits

Partners living with HIV encountered multi-level stigma, including anticipated, enacted, internalised, and perceived forms. Women in serodifferent relationships often felt disempowered by their HIV status. They were affected by hurtful remarks from their spouses, which they interpreted as a lack of agency within the partnership. Additionally, others faced ongoing interpersonal stigma from individuals outside their relationships, negatively impacting their perceived quality of life despite the advantages of lifesaving ART and inclusion in society.

“The challenge I have is I do not have a voice in my relationship because of my status.… When [I] fight with my husband, he utters words that are hurtful, and that makes me believe that he does not value me; he sees me as a dead person.” (Female PLWH, 54 years).

First of all, even though these treatments exist, the stigma doesn’t go away. Even though you have these medications that make you feel better, the stigma remains. While you’re not excluded, the negative comments persist.” (Male partner without HIV, 28 years).

Cross-country reflections

Themes were consistent across Uganda and Tanzania, with similar emotional trajectories in disclosure and decision-making regarding relationships. However, differences emerged in how U = U information was delivered and internalised. In Uganda, nearly all participants described structured counselling sessions at the point of discordant diagnosis. These included detailed discussions on viral load monitoring, fixed adherence routines, and PrEP initiation for partners without HIV. Ugandan participants also used biomedical terms such as “viral load” and “undetectable,” indicating formal exposure to clinical information. In contrast, Tanzanian participants less frequently reported receiving direct counselling on U = U. Several acquired their understanding informally from partners or experience, and later through provider-led education. Descriptions such as the virus “sleeping” or medication “killing the virus” reflected more basic interpretations, possibly shaped by language accessibility. These differences may reflect variations in provider training, service delivery models, the broader use of English in Uganda, a peri-urban site and Tanzania, a rural site. Together, the findings underscore the importance of consistent provider communication, equitable access to prevention tools like PrEP, and targeted efforts to address misinformation and stigma to optimise U = U implementation across diverse health system contexts.

Discussion

This study explored how serodifferent couples in East Africa experienced U = U messaging within their relationships. Awareness of U = U is increasing globally but remains uneven and low among heterosexual couples, non - men who have sex with men populations and in sub-Saharan Africa [18, 24, 25]. In contrast to prior SSA studies where U = U awareness was low [25, 37], our findings showed that awareness of U = U was high among serodifferent couples in both countries, similar to recent qualitative studies within the region [26, 27], with all participants expressing that sustained viral suppression prevents sexual transmission of HIV. This may reflect the success of ongoing country HIV prevention initiatives and advocacy programs [38, 39]. Across both high- and low-income countries, healthcare providers remain the primary source of U = U information, and this has been associated with better ART adherence and viral suppression. However, limited communication from healthcare providers has contributed to an incomplete understanding of U = U [18, 27, 28].

Despite U = U awareness, a low level of understanding was mirrored in risk perception, where most participants described initial doubts or disbelief when first exposed to the message, similar to findings in Rwanda and Kenya [27, 40, 41]. Over time, lived experiences, such as partners without HIV consistently testing negative, and the couple having children who tested negative, helped build confidence in the science behind U = U, a shift also observed in prior studies [10, 26, 42–44]. This may suggest the important role of lived experience in reinforcing U = U messaging [42]. That is, HIV prevention programs could use personal narratives of living positively with serodifference and success stories to further affirm U = U’s effectiveness among couples who are uncertain.

While all couples in our study had disclosed their status to one another, many described fear and emotional distress surrounding initial disclosure. Anticipated stigma, fear of transmission and fear of rejection complicating the decision to disclose were recurring themes that mirrored concerns that have been reported in studies across SSA [26, 27, 30]. However, our findings also demonstrated how disclosure, when supported by provider-based and couple counselling, which included learning about U = U, substantially eased the emotional strain, creating a supportive environment for partners within the couple to process their serodifferent statuses. Similar to previous studies, counselling and education regarding U = U not only improved self-esteem and strengthened relationship bonds but also influenced sexual and fertility choices [2, 3, 18, 20].

Although U = U supported risk reduction, many couples chose to maintain additional prevention methods (e.g., PrEP, condoms) as reassurance. Similar patterns have been observed globally, where PrEP use often continues even within virally suppressed partnerships, providing additional reassurance and addressing concerns about adherence, fidelity, or VL monitoring [27, 45, 46]. In addition, trust in U = U may be undermined by inconsistent access to viral load monitoring, delayed lab results, or lack of health provider training [21, 37]. Timely and trusted viral load feedback may build further confidence. Previous research has highlighted the importance and effectiveness of integrated and optional HIV prevention strategies in the HIV response [47] and these insights suggest that for many, U = U is integrated into broader approaches to HIV prevention at personal, relational and systemic levels.

Stigma remained a barrier for participants in both countries. Community misconceptions and inconsistent provider messaging undermined confidence in U = U. Although U = U has multi-level benefits across the HIV care continuum, including reducing stigma and transforming public perceptions of people with HIV [18, 22, 25, 48], limited knowledge about the science behind U = U and stigmatising attitudes may have led to persistent misconceptions about transmission risks, impacting couple dynamics and behaviours. Increasing U = U awareness, improving ART accessibility, and simplifying treatment regimens are critical for addressing challenges like low adherence, viremia, and drug resistance, thereby ensuring U = U’s success in Sub-Saharan Africa [49].

Strengths and limitations

This study offers a unique contribution by focusing on the experiences of U = U among serodifferent couples in two East African settings. We focused on individual perspectives, thereby capturing the dynamics between both partners and providing a richer understanding of how U = U is negotiated, challenged, and affirmed within relationships. The separate interviews also allowed us to minimise social desirability bias and gendered power dynamics. However, several limitations should be acknowledged. First, all included couples had disclosed their HIV status, possibly limiting exploration of pre-disclosure experiences and may limit generalisability. Second, participants were recruited from sites with established HIV services, including PrEP access, and thus may not reflect the experience of couples in less resourced clinics.

Conclusions

This study highlights the value of integrating U = U messaging into routine HIV care in ways that go beyond information provision. Tailored, relationship-focused counselling with real-life examples may promote greater trust and uptake. In both countries, U = U could offer a pathway to strengthen relationship dynamics, reduce transmission fears, and support reproductive goals among HIV serodifferent couples. Embedding U = U within person-centred care, improving structural enablers, and addressing stigma may increase its impact. Tailoring strategies to national contexts while informed by both local insights and global best practice—may help operationalise U = U as an effective tool in combination HIV prevention. In Uganda, structured counselling offers a platform for further progress, while in Tanzania, formalising provider-led U = U messaging may address current gaps. Future research should explore U = U’s integration across diverse clinical and community settings.

Abbreviations

AIDS

Acquired immunodeficiency syndrome

ART

Antiretroviral Therapy

CDCI

Chronic Disease Clinic of Ifakara

HIV

Human Immuno-deficiency Virus

PLWH

People Living with HIV

PrEP

Pre-exposure Prophylaxis

SSA

Sub-Saharan Afric

U=U

Undetectable = Untransmittable

Authors' contributions

E.S. led the conceptualisation, funding acquisition, investigation, project administration and drafting of the original manuscript. T.M. contributed to the mentorship, study design, and project administration. A.N., V.K., L.S. and B.K. contributed to the study design, investigation and qualitative data analysis and reporting. G.M. contributed to the conceptualisation and design of the study. A.M. and M.W. contributed to the overall supervision of the study and manuscript writing. All authors edited and reviewed the manuscript.

Funding

This work was partly supported by the Early Career Royal Society of Tropical Medicine and Hygiene grant and partly by a study grant from the International AIDS Society, Mark Wainberg Fellowship Programme.

Data availability

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

This study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki. Ethical approval was obtained from the Tanzanian National Institute for Medical Research (NIMR/HQ/R.8a/Vol.IX/4286), the Ifakara Health Institute (IHI/IRB/No:02-2023), the Infectious Diseases Institute Research Ethics Committee (IDI-REC-2022-25) and the Uganda National Council for Science and Technology (HS2900ES). Written informed consent was obtained from all participants before participation.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.