Prior to October 2019, MHSS policy was for HIV clinic staff to advise patients that their sex partners and biological children should be tested for HIV and to record contacts’ HIV status in booklets issued to all patients with HIV. Facilities, however, did not have specific staff dedicated to the provision of APS, nor was there systemic, routine follow-up related to contact notification and testing.

The MHSS APS program supported by I-TECH launched in October 2019 and by October 2020 included 22 facilities in four regions of Namibia. Consideration was given to both the types of clients served (urban vs. partially urban/rural) by sites and the community-based APS service partner active in the regions. Additionally, sites were selected based on the volume of newly identified HIV-positive cases. Key components of this program included APS focal staff accountable for APS service delivery, additional training, and ongoing support and supervision. Each supported site had a full-time focal APS HIV testing counsellor and a trained nurse. The MHSS APS training curriculum was enhanced to include role plays, scenarios, new data collection instruments, and data entry sessions and was used to train APS focal persons and facility nurses. Site-level staff were supported through nurse mentors, clinical (physician) mentors, monitoring and evaluation officers, and HIV Testing Services (HTS) mentors. HTS mentors visited main sites monthly to provide onsite supervision and training.

The program sought to offer APS to two groups of index cases: 1) patients with new or recently diagnosed (within 3 months) HIV infection, and 2) previously diagnosed HIV-positive patients identified as interrupting HIV care or being viremic. The latter group included persons classified as having a history of interrupting care (i.e., people who miss clinical appointments or did not pick up ART ≥90 days) who were offered APS services upon reengagement in care, and people with a high viral load [HVL] (viral load>1000 copies/mL). Although the program focused on these groups, some other previously diagnosed HIV-positive patients also received APS.

Using a structured interview record (Supplemental Digital Content 1), staff asked index cases aged ≥14 to name and provide contact information for each of their sex partners over the preceding 24 months or, if the index case reported no sex partners in the prior 24 months, their most recent sex partner [5, 12]. It also included screening questions related to history or fear of intimate partner violence (IPV) and other safety concerns related to notifying sex partners. Staff did not encourage index cases with history or fear of IPV to notify sex partners but worked with index cases to develop a safe notification plan if that was the index case’s preference. Staff also elicited information about biological children from female index cases if the woman was not known to be HIV-negative when the child was born and while the child was breastfeeding, and from male index cases if the mother was deceased, known to have HIV, or had unknown HIV status. Index cases aged <14 (n=19) were included to trace their biological parents. Injection drug partners were not included in the APS program.

Index cases chose from the following contact notification plan options:

unassisted patient referral: index case physically brings the contact to the clinic or refers the contact using a referral card (HIV self-test kits were used as a tool to support unassisted patient referral and given with the referral card);

Staff routinely followed up with index cases two weeks after enrollment to elicit additional contacts and discuss changing the contact notification plan if an elicited contact remained unnotified or untested. Staff typically conducted three to four follow-up interactions with index cases.

Elicited contacts were defined as ineligible for HIV testing if they had a prior confirmed HIV-positive diagnosis, had a documented HIV-negative test in the prior 30 days, were deceased, or if the index case did not report contact information for them (e.g., phone number, address). Program staff confirmed prior HIV diagnoses using the national unique ART number and, if this process identified persons as interrupting HIV care (i.e., missed clinical appointment or pill pick up), staff supported their re-engagement. Following tracing and notification of contacts, HIV testing was conducted in either the health facility or in the community. Contacts eligible for new HIV testing but not tested resulted from either incomplete tracing or refusal of testing.

Sex partners who tested HIV-negative were offered PrEP. The 2021 Namibian National ART Guidelines recommend PrEP be offered to any, HIV-negative person who is at substantial risk, or strongly feels at substantial risk, of acquiring HIV [19]. Referral and linkage to PrEP services was done both through facility and community HIV counselling and testing. PrEP was offered onsite at APS facilities with PrEP initiation performed by PrEP trained nurses.

The structured interview record was designed to ensure uniform data collection on index cases and their contacts and to guide APS staff through the APS process. Facility staff identified people seeking testing as contacts if they presented with a referral card and by asking all testers their reason for testing. If index cases identified a contact as having tested at a different health facility, staff verified this testing history using that facility’s testing register and the contact’s name. Data on contact outcomes were recorded in the index case’s interview record and all interview records were entered into a secure REDCap electronic data capture tools hosted at the University of Washington (grant number UL1 TR002319) [20, 21].

Analyses describe the characteristics of index case who accepted APS and their contacts and separately summarize program outcomes along an APS cascade for newly diagnosed and previously diagnosed index cases. Cascade steps include program reach (number of eligible index cases offered APS; newly diagnosed index cases only); program acceptance (number of index cases enrolling in APS of those offered APS); and the number of contacts elicited, tested, newly diagnosed with HIV and previously diagnosed with HIV. We also calculate three APS outcome indices: the contact index (average number of contacts elicited per index case), testing index (average number of contacts tested per index case), and case-finding index (average number of contacts newly testing positive per index case) [12, 22].

We used generalized estimating equations (GEE), clustering by facility with Poisson distributions and log links, to evaluate whether there were statistically significant differences in APS outcomes between index cases with previously diagnosed versus newly diagnosed HIV. This analysis estimated the rate ratios for the number of sex partners elicited, tested, and newly diagnosed with HIV in the two index case groups.

This study was conducted under a routine data use protocol approved by the MHSS. All data included in this analysis were routinely collected, programmatic data. The study received a non-research determination from the University of Washington and was reviewed in accordance with human research protection procedures and was determined to be non-research, public health program activity.

Participation in the APS program was voluntary, and prior to enrollment all index cases, 14 years of age and older, underwent a standardized consent process which allowed them to decline APS and informed them that they could withdraw from participation at any time. For children too young to consent to participation in APS, under the age of 14, elicitation of contacts was conducted by asking the parent or guardian to name the biological mother and any siblings.

Through routine HIV testing and counselling services (HTS), 1,557 patients were newly diagnosed HIV-positive during the study period and eligible for APS services. Staff offered APS to 1,222 of 1,557 patients newly diagnosed and eligible for APS (reach=78%), of whom 1,094 (90%) accepted APS, and 1,040 of those accepting APS named at least one sex partner (95% of those who accepted APS and 85% of those offered APS) (Figure 1). Newly diagnosed index cases identified 1,155 sex partners (contact index=1.06), of whom 212 (18%) had previously diagnosed HIV infection reported by the index case at their initial APS interview. An additional 25 sex partners initially reported by index cases as not having a prior HIV diagnosis were found to have previously tested HIV-positive. Thirteen (1%) sex partners were deceased, 41 (4%) had HIV tested in the prior 30 days, and 9 (1%) had insufficient contact information to initiate an investigation. Of the remaining 855 sex partners eligible for HIV testing, 401 (47%) tested for HIV (testing index=0.37), of whom 150 (37%) were newly diagnosed with HIV infection (case-finding index=0.14). Thus, 377 (33%) of the 1,155 sex partners were HIV-positive, 227 (60%) of whom had a prior HIV diagnosis.

Of the 150 newly tested and diagnosed HIV-positive sex partners through APS, 145 (97%) were linked to HIV care and treatment. Among the 251 HIV-negative sex partners, 215 (86%) were offered PrEP, and 169 (67%) initiated PrEP.

Of the 1,094 newly diagnosed index cases, 502 identified 649 biological children (contact index=0.59), of whom 4 (0.6%) had previously diagnosed HIV infection known by the index case. The 502 index cases who identified biological children included 441 (88%) women, 58 men (12%) and 3 (0.6%) people with missing data on assigned sex at birth. Among 645 eligible biological children, 261 (40%) were newly tested for HIV and 19 (7%) were newly diagnosed with HIV (case-finding index=0.02).

Because clinics did not collect data on the total number of patients interrupting care and HVL patients, it was not possible to assess program reach among previously diagnosed HIV-positive index cases. Staff offered APS to 315 index cases with previously diagnosed HIV infection, of whom 280 (89%) accepted (Figure 2). The population offered APS included 275 HVL and 40 patients interrupting care, 248 (90%) and 32 (80%) of whom accepted APS, respectively. Previously diagnosed index cases identified 279 sex partners (contact index=1.0), of whom 100 (36%) had previously diagnosed HIV infection. Three sex partners (1%) initially reported by index cases as not having a prior HIV diagnosis were found to have previously tested HIV-positive, 2 (0.7%) sex partners were deceased, and 8 (3%) sex partners had a documented HIV-negative HIV test in the prior 30 days. Of the remaining 166 sex partners eligible for testing, 93 (56%) tested for HIV (testing index=0.33), of whom 25 (27%) were newly diagnosed with HIV infection. The case-finding index among persons with previously diagnosed index cases was 0.09. Of the 280 index cases with previously diagnosed HIV infection, 128 (46%) had an identified HIV-positive sex partner, 80% of whom had a prior HIV diagnosis.

Of the 25 newly diagnosed sex partners, 23 (92%) were linked to HIV care and treatment. Among the 68 HIV-negative sex partners, 56 (82%) were offered PrEP, and 50 (74%) initiated PrEP.

Of the 280 previously known HIV-positive index cases, 104 identified 158 biological children (contact index=0.56), of whom 14 (9%) had previously diagnosed HIV infection known by the index case. Among 144 biological children eligible for testing, 43 (30%) were newly tested for HIV and 4 (9%) were newly diagnosed HIV-positive (case-finding index=0.01).

Although the case-finding index was higher among index cases newly diagnosed with HIV compared to index cases with previously diagnosed HIV (0.14 versus 0.09), the number of sex partners elicited, tested, and newly diagnosed HIV-positive between the two groups was not statistically different (Table 2).

Our study has several limitations. We could not assess if contacts tested in a facility other than the facility where the index case who named them received APS. We also lacked data on whether contacts tested through community-based testing. As a result, our estimates of the proportion of partners tested and newly diagnosed are likely low. We also were unable to estimate program reach among previously diagnosed HIV-positive persons who interrupted HIV care or who had HVL and could not evaluate the proportion of previously diagnosed partners who interrupted HIV care or off antiretroviral medications and who relinked to care through APS. Our team did not have access to national Adverse Event (AE) incident report data at the time of this analysis and consequently could not report data on AEs following receipt of APS. An assessment program costs and cost-effectiveness of APS relative to other testing modalities was not included in this study, such an analysis would be worthwhile. Finally, our findings may not be generalizable to other countries or other parts of Namibia.

In conclusion, we found that an APS program in Namibia was effective, that APS provided to viremic index cases with previously diagnosed HIV infection was a useful case-finding tool, and that many HIV uninfected partners identified through APS accept referrals to and initiate PrEP. These findings occurred in a country in which an estimated 90% of HIV-positive persons know their HIV status, demonstrating the value of APS in countries nearing epidemic control. At the same time, APS only identified 11% of all HIV diagnoses in participating clinics during the study period, highlighting the fact that APS should be only one part of a robust and balanced HIV testing strategy.