Factors associated with engagement in HIV care for young people living with perinatally acquired HIV in England: An exploratory observational cohort study.

Identifying which young people living with perinatally acquired HIV (PHIV) are less likely to engage in care is crucial to allow targeted interventions to support them to attend clinic. We adapted an existing Engagement in Care (EIC) algorithm for adults with HIV in England, for use in young people. We applied it to data from young people with PHIV in the Adolescents and Adults Living with Perinatal HIV (AALPHI) cohort. The algorithm predicts the timing of the next scheduled clinic visit, within 1-6 months of current visit, based on routine clinical data. Follow-up was 12-months from AALPHI baseline interview. Each person-month was classified as engaged in care or not. Logistic regression models (allowing for clustered data) were used to explore baseline characteristics associated with being engaged in care, adjusting for a priori variables (time from interview, sex, age, ethnicity, country of birth). Potential characteristics were across 7 domains: sociodemographic; risk behaviour practices; mental health; cognition; clinic setting; HIV management and experience; and HIV clinical markers. Of 316 young people, 187(59%) were female, 271(86%) of black ethnicity and 184(58%) born abroad. At baseline, median [IQR] age was 17[15-18] years, and 202(69%) had viral load ≤50 copies/ml(c/mL). 87% of 3,585 person-months were classified as engaged in care. Characteristics independently associated with poorer odds of being engaged in care were: Asian/mixed/other ethnicity, vs. black ethnicity (OR 0.44, 95% CI 0.25, 0.78, p = 0.02); ever self-harmed, vs. not (OR 0.55, 95% CI 0.32, 0.95, p = 0.03); on antiretroviral therapy (ART) and self-assessed bad/not so good adherence (OR 0.46, 95% CI 0.25, 0.84) or not on ART (OR 0.64, 95% CI 0.64, 1.21) vs. on ART and good/excellent adherence (p = 0.04)); baseline VL>50c/mL, vs VL≤50c/mL (OR 0.47, 95% CI 0.30, 0.75, p = 0.002). These characteristics can help identify individuals requiring enhanced support to maintain service engagement.

Disseminating the research findings from the adolescents and adults living with Perinatal HIV (AALPHI) study: an approach from young people living with HIV.

BACKGROUND: The Adolescents and Adults Living with Perinatal HIV (AALPHI) study is one of only three cohort studies worldwide evaluating the impact of HIV on young people living with perinatal HIV (PLHIV) relative to a comparable group of HIV negative young people in close relationship with an HIV positive individual, for example, their mother, sibling or partner. This project aimed to engage young people with the AALPHI study findings, help them take ownership, and decide how they would disseminate the key messages to both study participants and to the wider community. METHODS: In brief, 318 PLHIV and 100 HIV negative adolescents participated in AALPHI, where they each were interviewed twice, around two years apart. They were asked a wide range of psychosocial and risk behaviour questions and their cognitive function was assessed. We invited three AALPHI participants and seven members of the Youth Trials Board at the Children's HIV Association (CHIVA) to attend up to four workshops. They were provided with the key AALPHI research findings and asked to develop them into a format that was accessible and understandable for young people. Some who had not participated before formed a group in the fourth dissemination workshop that confirmed the most important concepts and results. RESULTS: The young people decided to develop a film and a leaflet about the AALPHI findings and co-produced them with a film maker and graphic designer. Challenges included working with the film maker and the venue for the first three dissemination workshops was an office space which was not ideal. CONCLUSION: Engaging young people in the dissemination of the AALPHI findings ensured the results were communicated in a way that was more likely to be relevant, accessible and useful to those affected by the study. This project demonstrates how young people in potentially stigmatised areas of care, such as HIV, can be involved in research dissemination.

Informing young people of the results of a study in which they participated, in a manner they can understand, is an ethical minimum. Increasingly, young people themselves may be involved in this dissemination activity, to ensure that study results are communicated in a way which is more likely to be relevant, accessible and useful to those directly affected by the study. The Adolescents and Adults Living with Perinatal HIV (AALPHI) study is a cohort study evaluating the impact of HIV on young people living with perinatal HIV (PLHIV) relative to HIV negative young people affected by HIV. This project aimed to engage PLHIV with the AALPHI findings, and help them take ownership of their dissemination, deciding how to communicate key messages to study participants and the wider community. We invited three AALPHI participants and seven members of a Youth Trials Board at the Children's HIV Association, (CHIVA), to attend four workshops. We provided them with key AALPHI findings and asked them to develop them into an understandable format for young people. They co-produced the content for a film and a leaflet about the results, working with a film maker and graphic designer. The 4th comprised of three workshop participants and seven new participants from CHIVA. This work shows that young PLHIV can be part of the process of evaluating study results and guiding dissemination by creating outputs that align with young people's priorities. This area of work could be further developed in the future through direct evaluation of participant involvement.

Stronger and durable SARS-CoV-2 immune response to mRNA vaccines in 5-11 years old children with prior COVID-19.

BACKGROUND AND OBJECTIVES: mRNA vaccines elicit a durable humoral response to SARS-CoV-2 in adults, whereas evidence in children is scarce. This study aimed to assess the early and long-term immune response to the mRNA vaccine in children with or without previous SARS-CoV-2 infection. METHODS: In a multicentre prospective observational study, we profiled the immune response to the Pfizer BioNTech (BNT162b2) vaccine in 5-11-year-old children attending the University Pediatric Hospital of Padua and Bambino-Gesù Hospital in Rome (Italy) from December-2021 to February-2023. Blood samples were collected pre-, 1-, and 6-months after vaccination. Neutralizing antibodies (NAbs) and anti-spike-receptor-binding-domain (anti-S-RBD) IgG titers were analyzed through Plaque Reduction Neutralization Test (PRNT) and chemiluminescent immune-enzymatic assay (CLIA), respectively. Immune cell phenotypes were analyzed by flow cytometry. RESULTS: Sixty children (26 [43 %] female, median age = 8 years [IQR = 7-10.7]) were enrolled in the study, including 46 children with a laboratory-confirmed previous COVID-19 (SARS-CoV-2-recovered) and 14 SARS-CoV-2-naïve participants defined as the absence of antigen-specific antibodies before vaccination. SARS-CoV-2-recovered participants recorded higher anti-S-RBD IgG and Wild-type and Omicron BA.2 NAbs titers than SARS-CoV-2-naïve participants at both 1- and 6-months after vaccination. Antibody titers correlated with T (Tregs) and B (Bregs) regulatory cell frequencies in SARS-CoV-2-recovered children. Both SARS-CoV-2-recovered and SARS-CoV-2-naïve participants decreased antibody titers by approximately 100 to 250 % from 1 to 6 months. While children with immunocompromising underlying conditions developed immune responses comparable to those of healthy children, solid organ transplant recipients exhibited lower levels of NAbs and anti-S-RBD IgG titers, as well as reduced frequencies of Tregs and Bregs. CONCLUSIONS: mRNA vaccination triggered a higher production of specific anti-SARS-CoV-2 antibodies along with increased levels of regulatory cells in children with previous SARS-CoV-2 infection up to the following 6 months. These findings provide insights into boosting pre-existing immunity.

Evolution of CD4 T-Cell Count With Age in a Cohort of Young People Growing Up With Perinatally Acquired Human Immunodeficiency Virus.

BACKGROUND: Recent studies have shown a decrease in CD4 count during adolescence in young people with perinatally acquired human immunodeficiency virus (HIV, PHIV). METHODS: Young people with PHIV in the United Kingdom, followed in the Collaborative HIV Paediatric Study who started antiretroviral therapy (ART) from 2000 onward were included. Changes in CD4 count over time from age 10 to 20 years were analyzed using mixed-effects models, and were compared to published CD4 data for the gerneral population. Potential predictors were examined and included demographics, age at ART start, nadir CD4 z score (age-adjusted) in childhood, and time-updated viral load. RESULTS: Of 1258 young people with PHIV included, 669 (53%) were female, median age at ART initiation was 8.3 years, and the median nadir CD4 z score was -4.0. Mean CD4 count was higher in young people with PHIV who started ART before age 10 years and had a nadir CD4 z score ≥-4; these young people with PHIV had a decline in CD4 count after age 10 that was comparable to that of the general population. Mean CD4 count was lower in young people with PHIV who had started ART before age 10 and had a nadir CD4 z score <-4; for this group, the decline in CD4 count after age 10 was steeper over time. CONCLUSIONS: In children, in addition to starting ART at an early age, optimizing ART to maintain a higher CD4 z score during childhood may be important to maximizing immune reconstitution later in life.

An adapted algorithm for patient engagement in care for young people living with perinatal HIV in England.

BACKGROUND: Evidence suggests that engagement in care (EIC) may be worse in young people living with perinatal HIV (YPLPHIV) compared to adults or children living with HIV. We took a published EIC algorithm for adults with HIV, which takes patients' clinical scenarios into account, and adapted it for use in YPLPHIV in England, to measure their EIC. METHODS: The adult algorithm predicts when in the next 6 months the next clinic visit should be scheduled, based on routinely collected clinical indicators at the current visit. We updated the algorithm based on the latest adult guidelines at the time, and modified it for young people in paediatric care using the latest European paediatric guidelines. Paediatric/adolescent HIV consultants from the UK reviewed and adapted the resulting flowcharts. The adapted algorithm was applied to the Adolescent and Adults Living with Perinatal HIV (AALPHI) cohort in England. Data for 12 months following entry into AALPHI were used to predicted visits which were then compared to appointment attendances, to measure whether young people were in care in each month. Proxy markers (e.g. dates of CD4 counts, viral loads (VL)) were used to indicate appointment attendance. RESULTS: Three hundred sixteen patients were in AALPHI, of whom 41% were male, 82% of black African ethnicity and 58% born abroad. At baseline (time of AALPHI interview) median [IQR] age was 17 [15-18] years, median CD4 was 597 [427, 791] cells/µL and 69% had VL ≤50c/mL. 10 patients were dropped due to missing data. 306 YPLPHIV contributed 3,585 person months of follow up across the 12 month study in which a clinic visit was recorded for 1,204 months (38/1204 dropped due to missing data). The remaining 1,166 months were classified into 3 groups: Group-A: on ART, VL ≤ 50c/mL-63%(734/1,166) visit months, Group-B: on ART, VL > 50c/mL-27%(320/1,166) Group-C: not on ART-10%(112/1,166). Most patients were engaged in care with 87% (3,126/3,585) of months fulfilling the definition of engaged in care. CONCLUSIONS: The adapted algorithm allowed the varying clinical scenarios of YPLPHIV to be taken into account when measuring EIC. However availability of good quality surveillance data is crucial to ensure that EIC can be measured well.

Comparative study showed that children faced a 78% higher risk of new-onset conditions after they had COVID-19.

AIM: Children have largely been unaffected by severe COVID-19 compared to adults, but data suggest that they may have experienced new conditions after developing the disease. We compared outcomes in children who had experienced COVID-19 and healthy controls. METHODS: A retrospective nested cohort study assessed the incidence rate of new-onset conditions after COVID-19 in children aged 0-14 years. Data were retrieved from an Italian paediatric primary care database linked to Veneto Region registries. Exposed children with a positive nasopharyngeal swab were matched 1:1 with unexposed children who had tested negative. Conditional Cox regression was fitted to estimate the adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for the exposure and outcome associations after adjusting for covariates. RESULTS: We compared 1656 exposed and 1656 unexposed children from 1 February 2020 to 30 November 2021. The overall excess risk for new-onset conditions after COVID-19 was 78% higher in the exposed than unexposed children. We found significantly higher risks for some new conditions in exposed children, including mental health issues (aHR 1.8, 95% CI 1.1-3.0) and neurological problems (aHR 2.4, 95% CI 1.4-4.1). CONCLUSION: Exposed children had a 78% higher risk of developing new conditions of interest after COVID-19 than unexposed children.

Learning and memory function in young people with and without perinatal HIV in England.

Learning and memory are important for successful education and career progression. We assess these functions in young people (YP) with perinatal HIV (PHIV) (with or without a previous AIDS-defining illness) and a comparable group of HIV-negative YP. 234 PHIV and 68 HIV-negative YP completed 9 tests; 5 National Institutes of Health (NIH) Toolbox tests (2 executive function, 1 speed of information processing, 2 memory); 2 Hopkins Verbal Learning Test Revised (HVLT-R) (learning (L), delayed recall (R)), and 2 verbal application measures. Z-scores for each test were calculated using normative data and averaged by domain where appropriate. The effect of predictors on test scores in the three domains with the lowest z-scores were analysed using linear regression. 139(59%) and 48(71%) PHIV and HIV-negative YP were female, 202(86%) and 52(76%) Black, and median age was 19 [17, 21] and 18 [16, 21] years respectively. 55(24%) PHIV had a previous Center for Disease Control and Prevention (CDC) class C AIDS-defining diagnosis (PHIV/C). For HVLT-R, there was a trend towards PHIV/C YP having the lowest mean z-scores (L -1.5 (95% CI -1.8,-1.2), R -1.7 (-2.0,-1.4)) followed by PHIV without a CDC C diagnosis (L -1.3 (-1.4,-1.1), R -1.4 (-1.5,-1.2)) and then the HIV-negative group (L -1.0 (-1.3,-0.7), R -1.1 (-1.3,-0.8)); all were greater than 1 SD below the reference mean. The same trend was seen for verbal application measures; however, z-scores were within 1 SD below the reference mean. NIH Toolbox tests were similar for all groups. In multivariable analyses PHIV/C and Black ethnicity predicted lower HVLT-R scores. Black ethnicity also predicted lower executive function scores, however each year increase in age predicted higher scores. In conclusion, cognitive performance in verbal learning and recall fell below population normative scores, and was more pronounced in PHIV/C, supporting wider findings that earlier antiretroviral therapy initiation, before the occurrence of AIDS-defining conditions, may protect aspects of cognitive development.

Factors Associated With Nonadherence to Antiretroviral Therapy Among Young People Living With Perinatally Acquired HIV in England.

Young people living with perinatally acquired HIV may be at risk of poor adherence to antiretroviral therapy; identification of predictors, using a conceptual framework approach proposed previously by others, is important to identify those at higher risk. In 261 young people with perinatally acquired HIV in England, 70 (27%) reported 3-day nonadherence, 82 (31%) last month nonadherence, and 106 (41%) nonadherence on either measure. Of those reporting nonadherence on both measures, 52% (23/44) had viral load of <50 copies/ml, compared with 88% (127/145) of those reported being fully adherent. In multivariable analysis, young person and medication theme factors were associated with nonadherence. The main predictors of 3-day nonadherence were antiretroviral therapy containing a boosted protease inhibitor and poorer quality of life. Predictors of last month nonadherence were having told more people about one's HIV status, worse self-perception about having HIV, and boosted protease inhibitor-based regimens. The consistency of individual young person and medication factors in predicting nonadherence gives insight into where interventions may best be targeted to improve adherence.

Self-harm in young people with perinatal HIV and HIV negative young people in England: cross sectional analysis.

BACKGROUND: Self-harm in adolescents is of growing concern internationally but limited evidence exists on the prevalence of self-harm in those living with HIV, who may be at higher risk of poor mental health outcomes. Therefore our aim was to determine the prevalence and predictors of self-harm among young people with perinatally-acquired HIV (PHIV) and HIV negative (with sibling or mother living with HIV) young people living in England. METHODS: 303 PHIV and 100 HIV negative young people (aged 12-23 years) participating in the Adolescents and Adults Living with Perinatal HIV cohort study completed an anonymous self-harm questionnaire, as well as a number of standardised mental-health assessments. Logistic regression investigated predictors of self-harm. RESULTS: The median age was 16.7 years in both groups, and 40.9% of the PHIV and 31.0% of the HIV negative groups were male. In total 13.9% (56/403) reported having ever self-harmed, with no difference by HIV status (p = 0.089). Multivariable predictors of self-harm were female sex (adjusted odds ratio (AOR) 5.3, (95% confidence interval 1.9, 14.1), p = 0.001), lower self-esteem (AOR 0.9 (0.8, 0.9) per 1 point increase, p < 0.001) and having ever used alcohol (AOR 3.8 (1.8, 7.8), p < 0.001). Self-esteem z-scores for both PHIV and HIV negative participants were 1.9 standard deviations below the mean for population norms. CONCLUSIONS: Self-harm is common among PHIV and HIV negative adolescents in England. Reassuringly however, they do not appear to be at an increased risk compared to the general adolescent population (15-19% lifetime prevalence). The low level of self-esteem (compared to available normative data) in both groups is worrying and warrants further attention.

Sexual health of young people with perinatal HIV and HIV negative young people in England.

As adolescents with perinatal HIV (PHIV) survive into adulthood, gaining insight into sexual behaviour and risk-taking is important. Between 2013-2015, 296 PHIV aged 13-21 years and 96 HIV negative affected adolescents (13-23 years) were recruited to the Adolescents and Adults Living with Perinatal HIV (AALPHI) cohort in England. Sexual health data were collected through computer-assisted self-interview questionnaires. Quality of life and household deprivation were also measured. T-tests compared means, and χ2 proportions; logistic regression examined predictors of ever having sex. 120(41%) PHIV and 31(32%) HIV- young people were male, 254(86%) and 70(73%) were black, median age 16 [IQR 15,18] and 16 [14,18] years respectively. 77(26%) PHIV had a previous AIDS diagnosis. 93(32%) PHIV and 38(40%) HIV- had ever had sex; median number of partners was 3 [1,6] and 4 [1,6] respectively. 54 (41%) of 131 young people who were sexually active reported not always using condoms, including 32% (30/93) of PHIV. In multivariable analysis, older age, male sex, worse deprivation score, worse quality of life, and alcohol and/or drugs were associated with ever having sex, but not HIV status. 12/30 PHIV reporting unprotected sex had at least one HIV viral load ≥200c/ml in the previous 12 months. Age at first sex and number of sexual partners were similar among PHIV and HIV-, and comparable to normative data. In conclusion, small numbers of PHIV reported condomless sex with a detectable viral load, which could result in HIV transmission, indicating the need for targeted sexual health and ART adherence interventions for young people with perinatal HIV.

Anxiety and depression symptoms in young people with perinatally acquired HIV and HIV affected young people in England.

Adolescents with perinatal HIV (PHIV) may be at higher risk of anxiety and depression than HIV negative young people. We investigated prevalence of anxiety and depression symptoms in 283 PHIV and 96 HIV-affected (HIV-negative) young people in England recruited into the Adolescents and Adults Living with Perinatal HIV (AALPHI) cohort. We used Hospital Anxiety and Depression Scale (HADS) scores and linear regression investigated predictors of higher (worse) scores.115 (41%) and 29 (30%) PHIV and HIV-affected young people were male, median age was 16 [interquartile range 15,18] and 16 [14,18] years and 241 (85%) and 71 (74%) were black African, respectively. There were no differences in anxiety and depression scores between PHIV and HIV-affected participants. Predictors of higher anxiety scores were a higher number of carers in childhood, speaking a language other than English at home, lower self-esteem, ever thinking life was not worth living and lower social functioning. Predictors of higher depression scores were male sex, death of one/both parents, school exclusion, lower self-esteem and lower social functioning. In conclusion, HIV status was not associated with anxiety or depression scores, but findings highlight the need to identify and support young people at higher risk of anxiety and depression.

Cognitive Function in Young Persons With and Without Perinatal HIV in the AALPHI Cohort in England: Role of Non-HIV-Related Factors.

BACKGROUND: There is limited evidence about the cognitive performance of older adolescents with perinatally acquired human immunodeficiency virus (HIV) compared with HIV-negative (HIV-) adolescents. METHODS: A total of 296 perinatally HIV-infected (PHIV+) and 97 HIV- adolescents (aged 12-21 and 13-23 years, respectively) completed 12 tests covering 6 cognitive domains. The HIV- participants had PHIV+ siblings and/or an HIV-infected mother. Domain-specific and overall (NPZ-6) z scores were calculated for PHIV+ participants, with or without Centers for Disease Control and Prevention (CDC) stage C disease, and HIV- participants. Linear regression was performed to explore predictors of NPZ-6. RESULTS: One hundred twenty-five (42%) of the PHIV+ and 31 (32%) of the HIV- participants were male; 251 (85%) and 69 (71%), respectively, were black African; and their median ages (interquartile range) were 16 (15-18) and 16 (14-18) years, respectively. In PHIV+ participants, 247 (86%) were receiving antiretroviral therapy, and 76 (26%) had a previous CDC C diagnosis. The mean (standard deviation) NPZ-6 score was -0.81 (0.99) in PHIV+ participants with a CDC C diagnosis (PHIV+/C), -0.45 (0.80) in those without a CDC C diagnosis (PHIV+/no C), and -0.32 (0.76) in HIV- participants (P < .001). After adjustment, there was no difference in NPZ-6 scores between PHIV+/no C and HIV- participants (adjusted coefficient, -0.01; 95% confidence interval, -.22 to .20). PHIV+/C participants scored below the HIV- group (adjusted coefficient, -0.44; -.70 to -.19). Older age predicted higher NPZ-6 scores, and black African ethnicity and worse depression predicted lower NPZ-6 scores. In a sensitivity analysis including PHIV+ participants only, no HIV-related factors apart from a CDC C diagnosis were associated with NPZ-6 scores. CONCLUSIONS: Cognitive performance was similar between PHIV+/no C and HIV- participants and indicated relatively mild impairment compared with normative data. The true impact on day-to-day functioning needs further investigation.

Episodic medication adherence in adolescents and young adults with perinatally acquired HIV: a within-participants approach.

Due to the success of antiretroviral (ART) medications, young people living with perinatally acquired HIV (PHIV+) are now surviving into adolescence and young adulthood. Understanding factors influencing ART non-adherence in this group is important in developing effective adherence interventions. Most studies of ART adherence in HIV-positive populations assess differences in adherence levels and adherence predictors between participants, over a period of time (global adherence). Many individuals living with HIV, however, including PHIV+ young people, take medication inconsistently. To investigate this pattern of adherence, a within-participants design, focussing on specific episodes of adherence and non-adherence, is suitable (episodic adherence). A within-participants design was used with 29 PHIV+ young people (17 female, median age 17 years, range 14-22 years), enrolled in the UK Adolescents and Adults Living with Perinatal HIV cohort study. Participants were eligible if they could identify one dose of medication taken and one dose they had missed in the previous two months. For each of the two episodes (one adherent, one non-adherent), behavioural factors (whom they were with, location, routine, day, reminders) and psychological factors at the time of the episode (information about medication, adherence motivation, perceived behavioural skills to adhere to medication - derived from the Information-Motivation-Behavioural Skills (IMB) Model - and affect) were assessed in a questionnaire. Non-adherence was significantly associated with weekend days (Friday to Sunday versus Monday to Thursday, p = .001), lack of routine (p = .004), and being out of the home (p = .003), but not with whom the young person was with or whether they were reminded to take medication. Non-adherence was associated with lower levels of behavioural skills (p < .001), and lower positive affect (p = .005). Non-adherence was not significantly associated with negative affect, information about ART, or ART motivation. The use of situationally specific strategies to enhance adherence in young people who take their medication inconsistently is proposed.

Plasma pharmacokinetics of once- versus twice-daily lamivudine and abacavir: simplification of combination treatment in HIV-1-infected children (PENTA-13).

BACKGROUND: There are few data on plasma and intracellular pharmacokinetics (PK) of once-daily (q24h) nucleoside analogues in HIV-infected children. METHODS: Children aged 2-13 years receiving combination treatment containing lamivudine (3TC) (4 mg/kg) and/or abacavir (ABC) (8 mg/kg) twice daily (q12h) were included in this single-arm, open-label, crossover study. Intensive plasma PK sampling was performed at steady state, after which children switched to q24h dosing and PK sampling was repeated 4 weeks later. Daily area under the curve (AUC0-24) and peak level (Cmax) of q24h and q12h regimens were compared by geometric mean ratios (GMRs) with 90% confidence intervals (CIs). Children were followed for 24 weeks to evaluate safety and virological response. RESULTS: 24 children were enrolled, of whom 20 [median age (range) 5.6 (2.1-12.8) years] had evaluable PK data for 3TC (n=19) and/or ABC (n=14). GMRs of 3TC and ABC AUC0-24 and Cmax q24h versus q12h significantly exceeded 1.0. GMRs were not significantly different between children aged 2-6 versus 6-13 years old (P>0.08). Of note, 3TC Cmax values for both q12h and q24h were significantly lower in children aged 2-6 versus 6-13 years old. No child discontinued due to adverse events. At baseline, 16 out of 20 children had a viral load <100 copies/ml compared with 17 out of 19 at week 24. CONCLUSION: AUC0-24 and Cmax of both 3TC and ABC q24h were not inferior to q12h dosing in children. Insufficient results were obtained concerning intracellular levels of the active triphosphate moieties of both agents. Virological data did not indicate a marked difference in antiviral activity between q12h and q24h regimens.