Sharp increase in gonorrhoea notifications among young people, EU/EEA, July 2022 to June 2023.

Gonorrhoea cases increased steeply in women aged 20 to 24 years across 15 EU/EEA countries in July to December 2022 and January to June 2023 with, respectively, 73% and 89% more cases reported than expected, based on historical data from 2015 to 2019. Smaller increases among men due to heterosexual transmission were observed in nine EU/EEA countries. Interventions to raise awareness among young people about sexually transmitted infection risks are needed, emphasising the benefit of safe sexual practices and testing.

Effectiveness of Modified Vaccinia Ankara-Bavaria Nordic Vaccination in a Population at High Risk of Mpox: A Spanish Cohort Study.

BACKGROUND: With more than 7500 cases reported since April 2022, Spain has experienced the highest incidence of mpox in Europe. From 12 July onward, the modified vaccinia Ankara-Bavaria Nordic (MVA-BN) smallpox vaccine was offered as pre-exposure prophylaxis for those receiving pre-exposure prophylaxis for human immunodeficiency virus (HIV-PrEP). Our aim was to assess the effectiveness of 1 dose of MVA-BN vaccine as pre-exposure prophylaxis against mpox virus (MPXV) infection in persons on HIV-PrEP. METHODS: National retrospective cohort study between 12 July and 12 December 2022. Individuals aged ≥18 years receiving HIV-PrEP as of 12 July with no previous MPXV infection or vaccination were eligible. Each day, we matched individuals receiving a first dose of vaccine and unvaccinated controls of the same age and region. We used a Kaplan-Meier estimator, calculated risk ratios (RR) and vaccine effectiveness (VE = [1 - RR]x100). RESULTS: We included 5660 matched pairs, with a median follow-up of 62 days (interquartile range, 24-97). Mpox cumulative incidence was 5.6 per 1000 (25 cases) in unvaccinated and 3.5 per 1000 (18 cases) in vaccinated. No effect was found during days 0-6 post-vaccination (VE, -38.3; 95% confidence interval [CI], -332.7 to 46.4), but VE was 65% at ≥7 days (95% CI, 22.9 to 88.0) and 79% at ≥14 days (95% CI, 33.3 to 100.0) post-vaccination. CONCLUSIONS: One dose of MVA-BN vaccine offered protection against mpox in most-at-risk population shortly after the vaccination. Further studies need to assess the VE of a second dose and the duration of protection over time.

Vaccination trends in people with HIV infection participanting in the hospital-based survey of patients infected with HIV, 2006-2021.

OBJECTIVE: To assess the trend in hepatitis A, hepatitis B, pneumococcal, tetanus and seasonal influenza vaccination in people with HIV infection and to analyse associated factors. METHODS: The Hospital Survey of Patients with HIV, an annual cross-sectional study conducted on a fixed day (2006-2021), was used. Inpatients and outpatients were included. Trends in vaccination and associated factors were analysed using logistic regression. RESULTS: A total of 8643 participants were included. Vaccination rates increased to 65.3% for hepatitis A, 83.7% for hepatitis B, 49.3% for tetanus, 68.9% for pneumococcal and 74.5% for seasonal influenza in 2021. Factors positively associated with vaccination were older age for pneumococcal and influenza vaccination; higher educational level for hepatitis A and tetanus; living in a closed institutions or prison for tetanus, pneumococcal and influenza; and having acquired HIV through sex between men for hepatitis A, B and pneumococcal. In addition, being on antiretroviral treatment and having a high CD4 count were positively associated with vaccination for all these diseases. Factors inversely associated with vaccination were being older (hepatitis A, B and tetanus), being an immigrant (tetanus and seasonal influenza) and being an injection drug user/ex-user for hepatitis A and B. CONCLUSIONS: Vaccination in people with HIV has increased in the study period. The results are in line with the recommendations in this population, although there is still room to reach the established vaccination indicators.

Estimates of mpox effective reproduction number in Spain, April-August 2022.

We analysed the transmission of the human mpox virus in Spain by estimating the effective reproduction number of the disease from official surveillance data. Our computations show that this decreased steadily after an initial burst phase, dropping below 1 on July 12, and thus the outbreak was expected to reduce in the following weeks. Differences in trends were found across geographical regions of the country and across MSM and heterosexual populations.

Correction: Monitoring progress towards elimination of hepatitis B and C in the EU/EEA.

[This corrects the article DOI: 10.1371/journal.pgph.0000841.].

Effectiveness and tolerability of dolutegravir/lamivudine for the treatment of HIV-1 infection in clinical practice.

OBJECTIVES: To assess the effectiveness and tolerability of dolutegravir (DTG)/lamivudine (3TC) among treatment-naive and virologically suppressed treatment-experienced individuals in the multicentre cohort of the Spanish HIV/AIDS Research Network (CoRIS) during the years 2018-2021. METHODS: We used multivariable regression models to compare viral suppression (VS) [HIV RNA viral load (VL) <50 copies/mL] and the change in CD4 cell counts at 24 and 48 (±12) weeks after initiation with dolutegravir/lamivudine or other first-line ART regimens. RESULTS: We included 2160 treatment-naive subjects, among whom 401 (18.6%) started with dolutegravir/lamivudine. The remaining subjects started bictegravir (BIC)/emtricitabine (FTC)/tenofovir alafenamide (TAF) (n = 949, 43.9%), DTG + FTC/tenofovir disoproxil fumarate (TDF) (n = 282, 13.1%), DTG/3TC/abacavir (ABC) (n = 255, 11.8%), darunavir (DRV)/cobicistat(COBI)/FTC/TAF (n = 147, 6.8%) and elvitegravir (EVG)/COBI/FTC/TAF (n = 126, 5.8%). At 24 and 48 weeks after starting dolutegravir/lamivudine, 91.4% and 93.8% of the subjects, respectively, achieved VS. The probability of achieving VS with dolutegravir/lamivudine was not significantly different compared with any other regimen at 24 or 48 weeks, with the exception of a lower chance of achieving VS at 24 weeks for DRV/COBI/FTC/TAF (adjusted OR: 0.47; 95% CI: 0.30-0.74) compared with dolutegravir/lamivudine.For the analysis of treatment-experienced virally suppressed subjects we included 1456 individuals who switched to dolutegravir/lamivudine, among whom 97.4% and 95.5% maintained VS at 24 and 48 weeks, respectively. During the first 48 weeks after dolutegravir/lamivudine initiation, 1.0% of treatment-naive and 1.5% of treatment-experienced subjects discontinued dolutegravir/lamivudine due to an adverse event. CONCLUSIONS: In this large multicentre cohort, effectiveness and tolerability of dolutegravir/lamivudine were high among treatment-naive and treatment-experienced subjects.

COVID-19 pandemic in prisons in Spain: characteristics of cases and implemented control measures, March 2020-June 2022.

OBJECTIVES: Our aim was to describe the epidemiological characteristics of COVID-19 cases in prison inmates in Spain and the control measures implemented to response to this public health challenge. STUDY DESIGN: Retrospective observational study. METHODS: All COVID-19-confirmed cases reported to the Spanish information system in prisons between March 2020 and June 2022 were analyzed. Prevention plans and protocols established by penitentiary and health authorities were reviewed. Likewise, information on vaccines administered to prison inmates was described. RESULTS: A total of 8500 COVID-19 cases were reported to penitentiary public health surveillance. The overall cumulative incidence (CI) was 2054.18 cases per 10,000 inmate population. By epidemic periods, the average weekly CI was 1.15 per 10,000 inmate population during the first period, 6.91 during the second, 25.18 during the third, 3.53 during the fourth, 23.27 during the fifth, 34.72 during the sixth and 25.68 during the seventh period. The median age of cases was 49.2 years, 69.1% was born in Spain, 64.1% was asymptomatic and 16 cases died. Ninety-four percent were vaccinated. Control measures such as lockdown, suspending visitation rights and confining inmates in their cells were adopted at the beginning of the pandemic. These measures changed in accordance with the COVID-19 situation in the general population with a view to restoring the inmates' rights. CONCLUSION: The COVID-19 pandemic has had a moderate incidence in Spanish prisons. Hospitalization and CFR were lower than the general population. The control measures adopted against COVID-19 have contributed to preventing and controlling the number of cases in prisons.

Tenofovir disoproxil fumarate/emtricitabine and severity of coronavirus disease 2019 in people with HIV infection.

BACKGROUND: Effective, safe, and affordable antivirals are needed for coronavirus disease 2019 (COVID-19). Several lines of research suggest that tenofovir may be effective against COVID-19, but no large-scale human studies with appropriate adjustment for comorbidities have been conducted. METHODS: We studied HIV-positive individuals on antiretroviral therapy (ART) in 2020 at 69 HIV clinics in Spain. We collected data on sociodemographics, ART, CD4+ cell count, HIV-RNA viral-load, comorbidities and the following outcomes: laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, COVID-19 hospitalization, intensive care unit (ICU) admission and death. We compared the 48-week risks for individuals receiving tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC), tenofovir alafenamide (TAF)/FTC, abacavir (ABC)/lamivudine (3TC), and other regimes. All estimates were adjusted for clinical and sociodemographic characteristics via inverse probability weighting. RESULTS: Of 51 558 eligible individuals, 39.6% were on TAF/FTC, 11.9% on TDF/FTC, 26.6% on ABC/3TC, 21.8% on other regimes. There were 2402 documented SARS-CoV-2 infections (425 hospitalizations, 45 ICU admissions, 37 deaths). Compared with TAF/FTC, the estimated risk ratios (RR) (95% confidence interval) of hospitalization were 0.66 (0.43, 0.91) for TDF/FTC and 1.29 (1.02, 1.58) for ABC/3TC, the RRs of ICU admission were 0.28 (0.11, 0.90) for TDF/FTC and 1.39 (0.70, 2.80) for ABC/3TC, and the RRs of death were 0.37 (0.23, 1.90) for TDF/FTC and 2.02 (0.88-6.12) for ABC/3TC. The corresponding RRs of hospitalization for TDF/FTC were 0.49 (0.24, 0.81) in individuals ≥50 years and 1.15 (0.59, 1.93) in younger individuals. DISCUSSION: Compared with other antiretrovirals, TDF/FTC lowers COVID-19 severity among HIV-positive individuals with virological control. This protective effect may be restricted to individuals aged 50 years and older.

A large multi-country outbreak of monkeypox across 41 countries in the WHO European Region, 7 March to 23 August 2022.

Following the report of a non-travel-associated cluster of monkeypox cases by the United Kingdom in May 2022, 41 countries across the WHO European Region have reported 21,098 cases and two deaths by 23 August 2022. Nowcasting suggests a plateauing in case notifications. Most cases (97%) are MSM, with atypical rash-illness presentation. Spread is mainly through close contact during sexual activities. Few cases are reported among women and children. Targeted interventions of at-risk groups are needed to stop further transmission.

Social and behavioural determinants of syphilis: Modelling based on repeated cross-sectional surveys from 2010 and 2017 among 278,256 men who have sex with men in 31 European countries.

Background: Syphilis case notifications among men-who-have-sex-with-men (MSM) have increased markedly over the past two decades in Europe. We tested several potential factors for this resurgence. Methods: Self-reported data from two cross-sectional waves of the European MSM Internet Survey (EMIS-2010 and EMIS-2017, N = 278,256 participants living in 31 European countries) were used to fit multivariable hierarchical logistic regression models designed to evaluate potential social, behavioural, and interventional determinants of syphilis diagnosis. Additional multivariable hierarchical negative binomial models investigated determinants of the number of non-steady male condomless anal intercourse (CAI) partners. We tested the hypothesis that more CAI and syphilis-screening are associated with syphilis resurgence, both linked to use of pre-exposure prophylaxis (PrEP). Findings: Between 2010 and 2017, incidence of syphilis diagnosis in the previous 12 months rose from 2.33% (95%CI: 2.26-2.40) of respondents reporting a syphilis diagnosis in 2010 compared with 4.54% (95%CI: 4.42-4.66) in 2017. Major factors contributing to syphilis diagnosis were living with diagnosed HIV (adjusted odds ratio (aOR) 2.67, 95%CI: 2.32-3.07), each additional non-steady male CAI partner (aOR 1.01, 95%CI: 1.01-1.01), recency of STI-screening (previous month vs no screening, aOR 25.76, 95%CI: 18.23-36.41), selling sex (aOR 1.45, 95%CI: 1.27-1.65), and PrEP use (aOR 3.02, 95%CI: 2.30-3.96). Living with diagnosed HIV (adjusted incidence rate ratio (aIRR) 3.91, 95%CI: 3.77-4.05), selling sex (aIRR 4.39, 95%CI: 4.19-4.59), and PrEP use (aIRR 5.82, 95%CI: 5.29-6.41) were associated with a higher number of non-steady male CAI partners. The association between PrEP use and increased chance of syphilis diagnosis was mediated by STI-screening recency and number of non-steady male CAI partners, both substantially higher in 2017 compared to 2010. Interpretation: Syphilis cases are concentrated in three MSM population groups: HIV-diagnosed, PrEP users, and sex workers. Behavioural and interventional changes, particularly more non-steady male CAI partners and recency of STI-screening, are major contributing factors for increasing syphilis diagnoses among MSM in Europe. Funding: European Centre for Disease Prevention and Control.

Transmission Clusters, Predominantly Associated With Men Who Have Sex With Men, Play a Main Role in the Propagation of HIV-1 in Northern Spain (2013-2018).

Viruses of HIV-1-infected individuals whose transmission is related group phylogenetically in transmission clusters (TCs). The study of the phylogenetic relations of these viruses and the factors associated with these individuals is essential to analyze the HIV-1 epidemic. In this study, we examine the role of TCs in the epidemiology of HIV-1 infection in Galicia and the Basque County, two regions of northern Spain. A total of 1,158 HIV-1-infected patients from both regions with new diagnoses (NDs) in 2013-2018 were included in the study. Partial HIV-1 pol sequences were analyzed phylogenetically by approximately maximum-likelihood with FastTree 2. In this analysis, 10,687 additional sequences from samples from HIV-1-infected individuals collected in Spain in 1999-2019 were also included to assign TC membership and to determine TCs' sizes. TCs were defined as those which included viruses from ≥4 individuals, at least 50% of them Spaniards, and with ≥0.95 Shimodaira-Hasegawa-like node support in the phylogenetic tree. Factors associated to TCs were evaluated using odds ratios (OR) and their 95% CI. Fifty-one percent of NDs grouped in 162 TCs. Male patients (OR: 2.6; 95% CI: 1.5-4.7) and men having sex with men (MSM; OR: 2.1; 95% CI: 1.4-3.2) had higher odds of belonging to a TC compared to female and heterosexual patients, respectively. Individuals from Latin America (OR: 0.3; 95% CI: 0.2-0.4), North Africa (OR: 0.4; 95% CI: 0.2-1.0), and especially Sub-Saharan Africa (OR: 0.02; 95% CI: 0.003-0.2) were inversely associated to belonging to TCs compared to native Spaniards. Our results show that TCs are important components of the HIV-1 epidemics in the two Spanish regions studied, where transmission between MSM is predominant. The majority of migrants were infected with viruses not belonging to TCs that expand in Spain. Molecular epidemiology is essential to identify local peculiarities of HIV-1 propagation. The early detection of TCs and prevention of their expansion, implementing effective control measures, could reduce HIV-1 infections.

Temporal Trends and Geographic Variability in the Prescription of Antiretroviral Treatments in People Living with HIV in Spain, 2004-2020.

BACKGROUND: The purpose of this study was to describe temporal trends in the use of antiretroviral therapy (ART) among people living with HIV (PLWHIV) from the cohort of the Spanish HIV/AIDS research network (CoRIS), 2004-2020. METHODS: We described the yearly evolution of the proportion of patients receiving ART and the most frequently prescribed antiretroviral drugs among newly recruited treatment-naïve patients and among all patients with active follow-up. RESULTS: Of 15,539 patients included, 14,618 (94.1%) started ART during their follow-up. Regarding initial regimens, the use of 2NRTI plus 1NNRTI (which were the most frequently prescribed until 2014) and 2NRTI plus 1bPI decreased after 2014, being gradually replaced by INI-based triple therapies. Since 2019, other regimens started to be prescribed, mainly dual therapies. TDF/FTC/EFV was the single-tablet regimen (STR) most frequently prescribed as initial ART until 2012, decreasing thereafter as TDF/FTC/RPV, TDF/FTC/EVG/COBI, and ABC/3TC/DTG became available. TAF/FTC/BIC accounted for 53.6% of initial prescriptions in 2020, followed by DTG/3TC (24%). The percentage of patients on ART increased from 45.7% in 2004 to 98.2% in 2020. Among all patients receiving ART, regimens based on 2NRTI plus 1INI increased from 0.1% in 2007 to 53.3% in 2020. During 2007-2015, most patients were receiving TDF/FTC/EFV, which was replaced after 2017 by ABC/3TC/DTG. In 2020, 13.0% of patients were receiving dual therapies. CONCLUSIONS: Robust real-world data on ART use in PLWHIV over more than 15 years show historical trends in prescriptions with an unprecedented visualization of the contemporary treatment patterns.

Factors associated with low levels of HIV testing among young men who have sex with men (MSM) participating in EMIS-2017 in Spain.

PURPOSE: The European Men who have sex with men Internet Survey looked over the characteristics and needs of men who have sex with men (MSM) across Europe. Our objective was to estimate the prevalence of HIV testing and its associated factors among MSM younger than 25 years old participating in the EMIS-2017 in Spain. METHODS: Multivariable regression model was used to compare those who had been tested for HIV within the last 12 months and those that had not. RESULTS: Of 2313 participants, 1070 (46.3%) had been tested for HIV in the past 12 months. Increased age (age 19-21 years, aOR=3.38 (95% CI 2.57 to 4.44); age 22-24 years, aOR=5.26 (4.06 to 6.92) compared with age 16-18 years); being migrant (Latin America: aOR=1.34 (0.98 to 1.84); Europe, North America and Mediterranean countries (aOR=1.56 (0.98 to 2.51) compared with those from Spain); living more openly with one's sexuality (out to some people (aOR=1.53 (1.19 to 1.96)); out to all or almost all people (aOR=2.24 (1.75 to 2.87) compared with those out to none or a few people); having had one condomless steady partners in the las year ((aOR=1.59 (1.26 to 2.02)); having had condomless non-steady partners in the last year (one: aOR=1.76 (1.35 to 2.29)); two or more partners: aOR=2.37 (1.84 to 3.04)); and having practised sex work in the past year (aOR=1.52 (1.07 to 2.13)) were associated with increased odds of HIV testing. Living in a smaller city was associated with less likelihood of HIV testing (<1 00 000 inhabitants: aOR=0.51 (95% CI 0.41 to 0.64); 100 000-500 000: aOR=0.68 (95% CI 0.54 to 0.86) compared with more than 500 000). CONCLUSION: Young MSM showed low HIV testing rate. Future programming specifically targeting this population, especially those middle adolescents, living in a medium-small city and having less 'outness', can help increase HIV testing and prevent access barriers.

Would eligible gay, bisexual and other men who have sex with men use PrEP? Awareness, knowledge, eligibility and intention to use PrEP among EMIS-2017 participants in Spain.

Pre-exposure prophylaxis (PrEP) is an efficacious strategy for reducing the incidence of HIV infection. It has been available in Spain since 2019. We aim to report on awareness, knowledge of, intention to use, and eligibility for PrEP and related factors among participants in the European Men-Who-Have-Sex-With-Men Internet Survey (EMIS-2017) in Spain. We used Spanish data from EMIS-2017, a cross-sectional study performed among gay, bisexual, and other men who have sex with mean (GBMSM) from 50 countries. We found that 65.3% of the 10,634 participants were aware of PrEP, some 30.1% of those HIV-negative and ≥ 18 years were eligible and 52.7% of those eligible intended to use it. Regarding knowledge about PrEP, only 15.4% of the participants knew 3 statement with true information about that PrEP meant. Older age, being born in Western Europe (WE) and greater outness were associated with greater awareness. Older age, being born in Latin America or Caribbean or WE, sex work, and living in a large city were associated with greater eligibility. A greater degree of outness was associated with reduced intention to use. Our study point to possible barriers in the implementation of PrEP in Spain and similar countries.

The impact of coronavirus disease 2019 on people with HIV.

PURPOSE OF REVIEW: The COVID-19 pandemic materialized in 2020, the year the international community had expected to meet the interim targets to end AIDS by 2030. Forty years into the HIV pandemic, the COVID-19 pandemic challenges the achievements made in HIV and may even reverse some of them. RECENT FINDINGS: This article provides an overview of the impact of COVID-19 on people with, and at risk of, HIV infection. It addresses where the global response to HIV was expected to be by 2020, analyzes the impact of COVID-19 on HIV-related outcomes and reviews the impact of HIV on COVID-19 related outcomes. SUMMARY: The COVID-19 pandemic has had a profound impact on the response to HIV infection through disruption of prevention, testing, and access to antiretroviral treatment, as well as on the management of long-term HIV and mental health. This negative impact has been unequal throughout the world and across populations and deepens inequities in health. HIV does not increase Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) susceptibility once confounders are taken into account and inconsistencies are reported regarding its direct role on clinical severity. In post-COVID-19 scenarios, new models for HIV testing and care are likely to be consolidated. Monitoring responses needs high-quality epidemiological data and collaborative research.

Monitoring progress towards elimination of hepatitis B and C in the EU/EEA.

This paper presents data on selected indicators to show progress towards elimination goals and targets for hepatitis B and hepatitis C in the 31 countries of the European Union (EU) and European Economic Area (EEA). A monitoring system was developed by the European Centre for Disease Prevention and Control, which combined newly collected data from EU/EEA countries along with relevant data from existing sources. Data for 2017 were collected from the EU/EEA countries via an online survey. All countries provided responses. In 2017, most countries reporting data had not reached prevention targets for childhood hepatitis B vaccination and for harm reduction services targeting people who inject drugs (PWID). Four of 12 countries had met the target for proportion of people living with chronic HBV diagnosed and seven of 16 met this target for hepatitis C. Data on diagnosed cases treated were lacking for hepatitis B. Of 12 countries reporting treatment data for hepatitis B, only Iceland met the target. This first collection of data across the EU/EEA highlighted major issues with data completeness and quality and in the indicators that were used, which impairs a clear overview of progress towards the elimination of hepatitis. The available data, whilst incomplete, suggest that as of 2017, the majority of the EU/EEA countries were far from meeting most of the 2020 targets, in particular those relating to harm reduction and diagnosis. It is critical to improve the data collected in order to develop more effective services for hepatitis prevention, diagnosis, and treatment that are needed in order to meet the 2030 elimination targets.

Prevalence and undiagnosed fraction of hepatitis C infection in 2018 in Spain: results from a national population-based survey.

BACKGROUND: A national strategy against hepatitis C virus (HCV) was implemented in Spain in 2015 with the aim of reducing associated morbidity and mortality. In order to improve our understanding of the epidemiology of HCV, we analysed the prevalence of HCV antibodies and active infection overall and by age and sex in the general population aged 20-80 years. We also aimed to report the undiagnosed fraction. METHODS: A national population-based seroprevalence survey was conducted in 2017-2018. A representative sample from the general population was selected using two-stage sampling. The prevalence of total HCV antibodies and of HCV RNA was calculated using inverse probability weighting based on bootstrapping. RESULTS: Overall, we approached 17 496 persons; 9103 agreed to participate and met the eligibility criteria and 7675 were aged 20-80. We obtained a prevalence of HCV antibodies of 0.85% [95% confidence interval (CI): 0.64-1.08%] and of active infection of 0.22% (95% CI: 0.12-0.32%). The prevalence of active HCV infection was highest in men aged 50-59 (0.86%; 95% CI: 0.28-1.57%) and in men aged 60-69 years (0.72%; 95% CI: 0.27-1.28%). Prevalence was below 0.20% in the remaining age groups. The undiagnosed fraction for active HCV infection was 29.4%. CONCLUSION: This study shows that prevalence of HCV in the general population in Spain is low and reflects the impact of scaling up treatment with direct acting antivirals, together with other prevention strategies, from 2015 onwards. The data reported can guide subsequent public health actions.

Recent infections among newly diagnosed cases of HIV infection in Spain, 2015-2016. National estimates using cohort data.

BACKGROUND: To estimate the prevalence of recent infection (RI) among people newly diagnosed with HIV in Spain using a representative sample collected by the AIDS Research Network cohort (CoRIS) during 2015-2016. METHODS: Stratified sampling of CoRIS data was used with proportional allocation by mode of transmission of new HIV diagnoses notified to National Surveillance System. Samples used were from patients in the CoRIS cohort with available stored plasma collected within 6 months after diagnosis. Weighted methods were used to estimate the prevalence of RI and multivariate logistic regression models were used to determine associated factors. RESULTS: Of the 669 individuals included, 55.1% were men who had sex with men (MSM), 24.6% were heterosexual, and 20.3% were non-MSM non-heterosexual. The weighted prevalence of RI was 11.8% (95% Confidence interval [CI] 9.4-14.8%) overall, 15.5% (12.2-19.4%) among MSM, 6.3% (3.9-10.0%) among heterosexual, and 8.6% (3.2-20.9%) in non-MSM non-heterosexual persons. Factors associated with prevalence of RI were: MSM (OR 2.05; 95% CI 1.02-4.14) vs. heterosexual, being Spanish (OR 2.92; 1.36-6.26) or European (OR 3.42; 1.28-9.13) vs. Latin American, having a secondary or higher education level (OR 3.08; 0.95-1.00) vs. primary, and having a CD4 count of 350-499 (OR 3.26; 1.46-7.30) or >500 (OR 6.26; 2.92-13.39) vs. <350 cells/mm3. CONCLUSIONS: In the absence of direct data from surveillance systems, the use of cohort data is a very valuable option for identifying the prevalence of RI at national level. This is the first nationwide study carried out in Spain to determine the prevalence of RI using an avidity assay.