Sex differences in the effectiveness and tolerability of dolutegravir plus rilpivirine as a switch strategy in people living with HIV.

INTRODUCTION: Dolutegravir + rilpivirine (DTG + RPV) is an effective antiretroviral therapy regimen approved in clinical guidelines as a switch therapy for virologically suppressed people with HIV. Our study aimed to compare the effectiveness and tolerability of DTG + RPV in women and men in real-world clinical practice. METHODS: This was a retrospective analysis of treatment-experienced people with HIV from a large HIV unit who switched to DTG + RPV. We analysed treatment effectiveness, rates of adverse events and discontinuation, and metabolic changes after 48 weeks of treatment. HIV-RNA levels <50 copies/mL were analysed at 48 weeks using both intention-to treat analysis (where missing data were interpreted as failures) and per-protocol analysis (excluding those with missing data or changes due to reasons other than virological failure). Outcomes were compared between women and men based on sex at birth. RESULTS: A total of 307 patients were selected (71 women and 236 men). No transgender people were included. At baseline, women had lived with HIV infection and received antiretroviral therapy for longer than men (23.2 vs 17.4 years and 18.9 vs 14.2 years, respectively). In the intention-to-treat analysis, 74.6% (95% confidence interval [CI] 63.4-83.3%) of women and 83.5% (95% CI 78.2-87.7) of men had HIV-RNA <50 copies/mL. In the per-protocol analysis, 96.4% (95% CI 87.7-99) of women and 99% (95% CI 98.9-99.7) of men had HIV-RNA levels <50 copies/mL. Two women and two men had HIV-RNA >50 copies/mL at 48 weeks. Discontinuation due to adverse events was more frequent in women than in men: 12.7% vs 7.2% (p < 0.02). Neuropsychiatric and gastrointestinal events were the most frequently reported. A median (interquartile range) weight gain of 1.9 kg (0-4.2) in women and 1.2 kg (-1-3.1) in men was reported (median of differences between baseline visit and week 48); the remaining changes in metabolic parameters were neutral. CONCLUSIONS: DTG + RPV exhibited good and similar virological effectiveness in women and men in real-world settings. However, poorer tolerability and more treatment interruptions were observed in women.

Epidemiological characteristic and prognosis changes in chronic hepatitis B in people living with HIV.

INTRODUCTION: Due to hepatitis B virus (HBV) treatment and vaccination during the last decades in Spain, epidemiological and prognosis of chronic hepatitis B (CHB) may have changed. METHODS: Retrospective review of CHB-HIV coinfected patients in a single reference center in Madrid until year 2019. We compared incidence, epidemiological and clinical characteristics according diagnosis period (before 2000, 2000-2004, 2005-2009, 2010-2014, 2015-2019). A retrospective longitudinal study was done to assess mortality, related risk factors and hepatic decompensation. RESULTS: Out of 5452 PLHIV, 160 had CHB (prevalence 2.92%; 95%CI 2.5-3.4), 85.6% were men, median age 32.1 (27-37.2). Incidence rate did not change over the years (2.4/100 patients-year). PLHIV with CHB diagnosed before year 2000 (n = 87) compared with those diagnosed between 2015 and 2019 (n = 11) were more often native-Spanish (90.8% vs. 18.2%), had infected using intravenous drugs (55.2% vs. 0), were coinfected with hepatitis C (40% vs. 9.1%) or hepatitis delta virus (30.4% vs. 0) and had more severe liver disease (cirrhosis 24.1% vs. 0). After a median follow-up of 20.4 years, 23 patients died (7.1/1000 patients-year) and 19 had liver decompensation (4.9/1000 patients-year). All deaths and liver decompensation occurred in patients diagnosed before year 2010. Mortality was associated with higher liver fibrosis in Fibroscan® (HR 1.06, 95% CI 1.03-1.09). CONCLUSION: The epidemiology of CHB in PLHIV in our cohort is changing with less native Spanish, more sexually transmitted cases and less coinfection with other hepatotropic virus. Patients diagnosed before 2010 have worst prognosis related to higher grades of liver fibrosis.

No changes in hemostasis after COVID-19-heterologous vaccination schedule: A subanalysis of the phase 2 CombiVacS study.

Background: Several cases of unusual thrombotic events and thrombocytopenia were described after vaccination with recombinant adenoviral vectors encoding the spike protein antigen of SARS-CoV-2. Objectives: The objective of this study was to elucidate the impact of a COVID-19 heterologous vaccination schedule, including priming with adenovirus vaccine, on hemostasis profiles. Methods: The present study is a subanalysis of the CombiVacS clinical trial initiated in April 2021 that included adult participants previously vaccinated with a single dose of ChAdOx1-S. Between 8 and 12 weeks after vaccination, they were randomly assigned (2:1) to receive either BNT162b2 vaccine (intervention group, n = 99) or continue observation (control group, n = 50). Samples drawn before and 28 days after a vaccination with BNT162b2 were analyzed for platelet count and markers of hemostasis (D-dimer, anti-PF4 antibodies, cfDNA, PAI-1, thrombin generation, and serum capacity to activate platelets). Results: Platelet count from all participants after receiving BNT162b2 was within the normal range. Anti-PF4 antibodies were present in 26% and 18% of the subjects from the control and intervention groups, respectively, at day 28. In most cases, the levels of anti-PF4 antibodies were high before receiving BNT162b2. Serum from these participants did not activate platelets from healthy controls. There were no differences between the groups in PAI-1 and cfDNA plasma levels. According to the D-dimer plasma concentration, the thrombin generation test showed that none of the participants had a procoagulant profile. Conclusion: Our data suggest that the heterologous vaccination against COVID-19 with ChAdOx1-S and a second dose with BNT162b2 might be safe in terms of haemostasis.

Treatment and prevention of monkeypox.

Monkeypox is a zoonosis that is spread mainly through direct contact with fluids and skin lesions of infected people with vesicles still active. Although the virus was isolated for the first time in 1958 and the first human case was identified in a child in 1970, in the Democratic Republic of the Congo, the disease has progressively increased its incidence in Africa reaching in May 2022 sustained transmission outside this continent. As it is a newly introduced virus in our health system, it is necessary to learn the epidemiological pattern in a different environment from that of traditionally endemic areas and to know the available antiviral treatments, as well as the prophylactic measures that could be considered, knowing that as a virus emerging in our regions, scientific evidence is still limited. There are antivirals that have been shown, in animal models, to effectively combat the disease with very good clinical tolerance. This disease has also forced us to review the characteristics of smallpox vaccines, because they have shown a protective effect against monkeypox. For this reason, it is important to have a document that compiles all the scientific information published in this regard.

Daily tenofovir disoproxil fumarate/emtricitabine and hydroxychloroquine for pre-exposure prophylaxis of COVID-19: a double-blind placebo-controlled randomized trial in healthcare workers.

OBJECTIVES: To assess the effect of hydroxychloroquine (HCQ) and Tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) as pre-exposure prophylaxis on COVID-19 risk. METHODS: EPICOS is a double-blind, placebo-controlled randomized trial conducted in Spain, Bolivia, and Venezuela. Healthcare workers with negative SARS-CoV-2 IgM/IgG test were randomly assigned to the following: daily TDF/FTC plus HCQ for 12 weeks, TDF/FTC plus HCQ placebo, HCQ plus TDF/FTC placebo, and TDF/FTC placebo plus HCQ placebo. Randomization was performed in groups of four. Primary outcome was laboratory-confirmed, symptomatic COVID-19. We also studied any (symptomatic or asymptomatic) COVID-19. We compared group-specific 14-week risks via differences and ratios with 95% CIs. RESULTS: Of 1002 individuals screened, 926 (92.4%) were eligible and there were 14 cases of symptomatic COVID-19: 220 were assigned to the TDF/FTC plus HCQ group (3 cases), 231 to the TDF/FTC placebo plus HCQ group (3 cases), 233 to the TDF/FTC plus HCQ placebo group (3 cases), and 223 to the double placebo group (5 cases). Compared with the double placebo group, 14-week risk ratios (95% CI) of symptomatic COVID-19 were 0.39 (0.00-1.98) for TDF + HCQ, 0.34 (0.00-2.06) for TDF, and 0.49 (0.00-2.29) for HCQ. Corresponding risk ratios of any COVID-19 were 0.51 (0.21-1.00) for TDF + HCQ, 0.81 (0.44-1.49) for TDF, and 0.73 (0.41-1.38) for HCQ. Adverse events were generally mild. DISCUSSION: The target sample size was not met. Our findings are compatible with both benefit and harm of pre-exposure prophylaxis with TDF/FTC and HCQ, alone or in combination, compared with placebo.

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.

Long-term Evaluation of Residual Viremia in a Clinical Trial of Dolutegravir Plus Lamivudine as Maintenance Treatment for Participants With and Without Prior Lamivudine Resistance.

In this pilot clinical trial, we evaluated rates of residual replication in persons without lamivudine resistance-associated mutations in proviral DNA population sequencing who switched to dolutegravir plus lamivudine. After 144 weeks, there was no signal of changes in residual viremia based on qualitative detection methods, irrespective of past lamivudine resistance. Clinical Trials Registration. NCT03539224.

[Treatment and prevention of monkeypox]. / Tratamiento y prevención de la viruela del mono.

Monkeypox is a zoonosis that is spread mainly through direct contact with fluids and skin lesions of infected people with vesicles still active. Although the virus was isolated for the first time in 1958 and the first human case was identified in a child in 1970, in the Democratic Republic of the Congo, the disease has progressively increased its incidence in Africa reaching in May 2022 sustained transmission outside this continent. As it is a newly introduced virus in our health system, it is necessary to learn the epidemiological pattern in a different environment from that of traditionally endemic areas and to know the available antiviral treatments, as well as the prophylactic measures that could be considered, knowing that as a virus emerging in our regions, scientific evidence is still limited. There are antivirals that have been shown, in animal models, to effectively combat the disease with very good clinical tolerance. This disease has also forced us to review the characteristics of smallpox vaccines, because they have shown a protective effect against monkeypox. For this reason, it is important to have a document that compiles all the scientific information published in this regard.

Immunogenic dynamics and SARS-CoV-2 variant neutralisation of the heterologous ChAdOx1-S/BNT162b2 vaccination: Secondary analysis of the randomised CombiVacS study.

Background: The CombiVacS study was designed to assess immunogenicity and reactogenicity of the heterologous ChAdOx1-S/BNT162b2 combination, and 14-day results showed a strong immune response. The present secondary analysis addresses the evolution of humoral and cellular response up to day 180. Methods: Between April 24 and 30, 2021, 676 adults primed with ChAdOx1-S were enrolled in five hospitals in Spain, and randomised to receive BNT162b2 as second dose (interventional group [IG]) or no vaccine (control group [CG]). Individuals from CG received BNT162b2 as second dose and also on day 28, as planned based on favourable results on day 14. Humoral immunogenicity, measured by immunoassay for SARS-CoV-2 receptor binding domain (RBD), antibody functionality using pseudovirus neutralisation assays for the reference (G614), Alpha, Beta, Delta, and Omicron variants, as well as cellular immune response using interferon-γ and IL-2 immunoassays were assessed at day 28 after BNT162b2 in both groups, at day 90 (planned only in the interventional group) and at day 180 (laboratory data cut-off on Nov 19, 2021). This study was registered with EudraCT (2021-001978-37) and ClinicalTrials.gov (NCT04860739). Findings: In this secondary analysis, 664 individuals (441 from IG and 223 from CG) were included. At day 28 post vaccine, geometric mean titres (GMT) of RBD antibodies were 5616·91 BAU/mL (95% CI 5296·49-5956·71) in the IG and 7298·22 BAU/mL (6739·41-7903·37) in the CG (p < 0·0001). RBD antibodies titres decreased at day 180 (1142·0 BAU/mL [1048·69-1243·62] and 1836·4 BAU/mL [1621·62-2079·62] in the IG and CG, respectively; p < 0·0001). Neutralising antibodies also waned from day 28 to day 180 in both the IG (1429·01 [1220·37-1673·33] and 198·72 [161·54-244·47], respectively) and the CG (1503·28 [1210·71-1866·54] and 295·57 [209·84-416·33], respectively). The lowest variant-specific response was observed against Omicron-and Beta variants, with low proportion of individuals exhibiting specific neutralising antibody titres (NT50) >1:100 at day 180 (19% and 22%, respectively). Interpretation: Titres of RBD antibodies decay over time, similar to homologous regimes. Our findings suggested that delaying administration of the second dose did not have a detrimental effect after vaccination and may have improved the response obtained. Lower neutralisation was observed against Omicron and Beta variants at day 180. Funding: Funded by Instituto de Salud Carlos III (ISCIII).

Past and future of HIV infection. A document based on expert opinion / Pasado y futuro de la infección por VIH. Un documento basado en la opinión de expertos

HIV infection is now almost 40 years old. In this time, along with the catastrophe and tragedy that it has entailed, it has also represented the capacity of modern society to take on a challenge of this magnitude and to transform an almost uniformly lethal disease into a chronic illness, compatible with a practically normal personal and relationship life. This anniversary seemed an ideal moment to pause and reflect on the future of HIV infection, the challenges that remain to be addressed and the prospects for the immediate future. This reflection has to go beyond merely technical approaches, by specialized professionals, to also address social and ethical aspects. For this reason, the Health Sciences Foundation convened a group of experts in different aspects of this disease to discuss a series of questions that seemed pertinent to all those present. Each question was presented by one of the participants and discussed by the group. The document we offer is the result of this reflection. (AU)

La infección por VIH cumple ahora casi 40 años de existencia. En este tiempo, junto a la catástrofe y la tragedia que ha supuesto, ha representado también la capacidad de la sociedad moderna de asumir un reto de esta magnitud y de transformar, gracias al tratamiento antirretroviral, una enfermedad mayoritariamente letal en una enfermedad crónica, compatible con una vida personal y de relación prácticamente normales. Este aniversario parecía un momento idóneo para pararse a reflexionar sobre el futuro de la infección VIH, los retos que todavía quedan por abordar y las perspectivas para el inmediato futuro. Esa reflexión tiene que ir más allá de planteamientos meramente técnicos, de profesionales especializados, para abordar aspectos sociales y éticos. Por este motivo, la Fundación de Ciencias de la Salud convocó a un grupo de expertos en distintos aspectos de esta infección para discutir una serie de preguntas que parecieron pertinentes a todos los convocados. Cada pregunta era expuesta por uno de los participantes y discutida por el grupo. El documento que ofrecemos es el resultado de esa reflexión. (AU)

Acute hepatitis B among HIV positive persons: A two-decade review of cases from a Spanish cohort.

PURPOSE: To review the incidence and characteristics of acute hepatitis B (AHB) in a large cohort of HIV infected persons from a low prevalence region during the last two decades. METHODS: Retrospective review of an HIV Cohort from a single reference centre in Madrid, Spain, between 2000 and 2018. AHB was diagnosed in persons with newly acquired HBAgS and acute hepatitis with positive IgM anti-HBc. RESULTS: Out of 5443 HIV+ patients in our cohort (3098 anti-HBc negative), 18 developed AHB from 2000 to 2018. The global incidence was 0.02 (0.01-0.04) per 100 patient-year in the entire population and 0.06 (0.01-0.1) per 100 patient-year in the anti-HBc negative population. A statistically significant decrease in AHB incidence was observed during these years (ß=-0.006; p=0.047). All 18 patients diagnosed with AHB were men, the majority (16) occurred in men who have sex with men. AHB was observed in 4 persons previously unresponsive to vaccination. Regarding antiretroviral treatment (ART), 15 were not receiving ART, two persons were on ART with any HBV active drugs and one person had lamivudine in the regimen. Two persons (11%) developed chronic hepatitis B. There were no cases of fulminant hepatitis. CONCLUSION: The incidence of AHB in HIV positive persons in our cohort was low and shows a progressive decline in the last 20 years. Cases occurred in persons not protected against VHB: not vaccinated or non-responders to vaccine that were not receiving tenofovir.

Ageing with HIV: Challenges and biomarkers.

The antiretroviral treatment (ART) developed to control HIV infection led to a revolution in the prognosis of people living with HIV (PLWH). PLWH underwent from suffering severe disease and often fatal complications at young ages to having a chronic condition and a life expectancy close to the general population. Nevertheless, chronic age-related diseases increase as PLWH age. The harmful effect of HIV infection on the individual's immune system adds to its deterioration during ageing, exacerbating comorbidities. In addition, PLWH are more exposed to risk factors affecting ageing, such as coinfections or harmful lifestyles. The ART initiation reverses the biological ageing process but only partially, and additionally can have some toxicities that influence ageing. Observational studies suggest premature ageing in PLWH. Therefore, there is considerable interest in the early prediction of unhealthy ageing through validated biomarkers, easy to implement in HIV-clinical settings. The most promising biomarkers are second-generation epigenetic clocks and integrative algorithms.

A Case-Control of Patients with COVID-19 to Explore the Association of Previous Hospitalisation Use of Medication on the Mortality of COVID-19 Disease: A Propensity Score Matching Analysis.

Data from several cohorts of coronavirus disease 2019 (COVID-19) suggest that the most common comorbidities for severe COVID-19 disease are the elderly, high blood pressure, and diabetes; however, it is not currently known whether the previous use of certain drugs help or hinder recovery. This study aims to explore the association of previous hospitalisation use of medication on the mortality of COVID-19 disease. A retrospective case-control from two hospitals in Madrid, Spain, included all patients aged 18 years or above hospitalised with a diagnosis of COVID-19. A Propensity Score matching (PSM) analysis was performed. Confounding variables were considered to be age, sex, and the number of comorbidities. Finally, 3712 patients were included. Of these, 687 (18.5%) patients died (cases). The 22,446 medicine trademarks used previous to admission were classified according to the ATC, obtaining 689 final drugs; all of them were included in PSM analysis. Eleven drugs displayed a reduction in mortality: azithromycin, bemiparine, budesonide-formoterol fumarate, cefuroxime, colchicine, enoxaparin, ipratropium bromide, loratadine, mepyramine theophylline acetate, oral rehydration salts, and salbutamol sulphate. Eight final drugs displayed an increase in mortality: acetylsalicylic acid, digoxin, folic acid, mirtazapine, linagliptin, enalapril, atorvastatin, and allopurinol. Medication associated with survival (anticoagulants, antihistamines, azithromycin, bronchodilators, cefuroxime, colchicine, and inhaled corticosteroids) may be candidates for future clinical trials. Drugs associated with mortality show an interaction with the underlying conditions.

Impact of early interferon-ß treatment on the prognosis of patients with COVID-19 in the first wave: A post hoc analysis from a multicenter cohort.

BACKGROUND: Interferon-ß is an attractive drug for repurposing and use in the treatment of COVID-19, based on its in vitro antiviral activity and the encouraging results from clinical trials. The aim of this study was to analyze the impact of early interferon-ß treatment in patients admitted with COVID-19 during the first wave of the pandemic. METHODS: This post hoc analysis of a COVID-19@Spain multicenter cohort included 3808 consecutive adult patients hospitalized with COVID-19 from 1 January to 17 March 2020. The primary endpoint was 30-day all-cause mortality, and the main exposure of interest was subcutaneous administration of interferon-ß, defined as early if started ≤ 3 days from admission. Multivariate logistic and Cox regression analyses were conducted to identify the associations of different variables with receiving early interferon-ß therapy and to assess its impact on 30-day mortality. A propensity score was calculated and used to both control for confounders and perform a matched cohort analysis. RESULTS: Overall, 683 patients (17.9%) received early interferon-ß therapy. These patients were more severely ill. Adjusted HR for mortality with early interferon-ß was 1.03 (95% CI, 0.82-1.30) in the overall cohort, 0.96 (0.82-1.13) in the PS-matched subcohort, and 0.89 (0.60-1.32) when interferon-ß treatment was analyzed as a time-dependent variable. CONCLUSIONS: In this multicenter cohort of admitted COVID-19 patients, receiving early interferon-ß therapy after hospital admission did not show an association with lower mortality. Whether interferon-ß might be useful in the earlier stages of the disease or specific subgroups of patients requires further research.

Detection of archived lamivudine-associated resistance mutations in virologically suppressed, lamivudine-experienced HIV-infected adults by different genotyping techniques (GEN-PRO study).

BACKGROUND: Previously selected lamivudine resistance-associated mutations (RAMs) may remain archived within the proviral HIV-DNA. OBJECTIVES: To evaluate the ability of proviral DNA genotyping to detect lamivudine RAMs in HIV-1 virologically suppressed participants; the correlation between Sanger and next generation sequencing (NGS); and predictive factors for detection of lamivudine RAMs in proviral DNA. METHODS: Cross-sectional study of participants on stable antiretroviral therapy and suppressed for ≥1 year. Analysis of proviral DNA was performed by Sanger sequencing in whole blood and by NGS in PBMCs. RESULTS: We analysed samples from 102 subjects (52 with and 50 without lamivudine RAMs in historical plasma RNA-genotypes). Among participants with previous lamivudine resistance, Sanger sequencing detected RAMs in 26.9%. Detection rates significantly increased using NGS: 47.9%, 64.6%, 75% and 87.5% with the 20%, 10%, 5% and 1% thresholds, respectively. As for participants without historical lamivudine resistance, Sanger detected the RAMs in 1/49 (2%), and NGS (5% threshold) in 8/45 (17.8%). Multivariate models fitted to the whole population revealed that having a history of lamivudine resistance was a risk factor for detection of lamivudine RAMs by NGS. Among participants with historical lamivudine resistance, multivariate analysis showed that a longer time since HIV diagnosis was associated with persistence of archived mutations by NGS at thresholds of >10% [OR 1.10 (95% CI: 1.00-1.24)] and >5% [OR 1.16 (95% CI: 1.02-1.32)]. CONCLUSIONS: Proviral DNA Sanger sequencing does not detect the majority of historical lamivudine RAMs. NGS increases the sensitivity of detection at lower thresholds, although the relevance of these minority populations with lamivudine RAMs needs further evaluation.

The seroprevalence of SARS-CoV-2 antibodies among health care workers before the era of vaccination: a systematic review and meta-analysis.

BACKGROUND: The prevalence of SARS-CoV-2 infection among health care workers (HCWs) provides information about the spread of COVID-19 within health care facilities, and the risk groups. OBJECTIVES: We aimed to describe the rate of SARS-CoV-2 seroprevalence and its determinants among HCWs. DATA SOURCES: We used Web of Science, PubMed, Scopus, MEDLINE, EBSCOhost and Cochrane Library. STUDY ELIGIBILITY CRITERIA: We included the reports of SARS-CoV-2 seroprevalence with a sample size of minimum 1000 HCWs. METHODS: The study was registered at the International Prospective Register of Systematic Reviews (PROSPERO, no. CRD42021230456). We used PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. The keywords were "COVID-19", "SARS-CoV-2", "Coronavirus", "seroprevalence", "health care workers" and "risk factors". RESULTS: In total 4329 reports were retrieved, duplications were removed; after filtering according to the title and abstract, 25 studies were selected. Risk of bias was assessed in 25 studies; it was low in 13 studies, medium in four studies, and high in eight studies. In meta-analysis using the random effect model, the weighted average of seroprevalence was calculated as 8% (95% CI 6-10%). The pooled seroprevalence rates of the selected variables that have a rate above the average were male HCWs with 9% (95% CI 7-11%); HCWs from ethnic minorities with 13% (95% CI 9-17%); high exposure 9% (95% CI 6-13%); exposure to the virus outside the health care setting 22% (95% CI 14-32%). CONCLUSIONS: Our analysis indicates a SARS-CoV-2 seroprevalence rate of 8% among studies that included >1000 HCWs for the year 2020, before vaccinations started. The most common risk factors associated with higher seroprevalence rate were ethnicity, male gender and having a higher number of household contacts. Working as a frontline HCW was inconsistent in its association with higher seroprevalence.