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Competing Interests: Los autores declaran que no tienen intereses en competencia.

HLA is a polymorphic antigen presenter which has provided valuable information on the susceptibility of populations to viruses. Therefore, the study of HLA can reveal specific susceptibility or resistance alleles to severe COVID-19 in an ethnically dependent manner. This pilot study investigated HLA alleles associated with COVID-19 severity in Tapachula, Chiapas, Mexico. A total of 146 Mexican Mestizos were typed for HLA class I and II using PCR-SSP. The patients were classified according to the outcome (death or improvement) and the infection's severity (mild or severe). In addition, a group of exposed uninfected individuals was included. HLA-A*68 was found to be a protective allele against the severe infection and fatal outcome; pC = 0.03, OR = 0.4, 95% CI =0.20-0.86, and pC =0.009, OR = 0.3, 95% CI =0.13-0.71 respectively. HLA-DRB1*03 also appears to be a protective factor against fatal outcome pC = 0.009, OR = 0.1, 95%IC = 0.01-0.66; however, the low frequency of this allele in the studied population limits the statistical power. The severity and fatal outcome of COVID-19 patients in Tapachula, Chiapas depend more on the lack of resistance than susceptibility HLA alleles., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: In the movement for global health equity, increased research and funding have not yet addressed a shortage of evidence on effectively implementing context-specific interventions; one unmet need is facilitating access to specialty care within the public health sector in Mexico. Compañeros en Salud has been piloting a novel program, called Right to Healthcare (RTHC), to increase access to specialty care for the rural poor in Chiapas, Mexico. The RTHC program incorporates social work, patient navigation, referrals, direct economic support, and accompaniment for patients., Objectives: This study evaluates the effectiveness of the RTHC program. Primary outcomes analyzed included acceptance of any referral and attendance of any appointment. Secondary outcomes included acceptance of the first referral and rate of appointment attendance for patients with an accepted referral., Methods: Using referral process data for the years 2014 to 2019 from a public tertiary care hospital in Chiapas, 91 RTHC patients were matched using 2:1 optimal pair matching with a control cohort balancing covariates of patient age, sex, specialty referred to, level of referring hospital, and municipality., Findings: RTHC patients were more likely to have had an accepted referral (OR 17.42, 95% CI 3.68 to 414.16) and to have attended an appointment (OR 5.49, 95% CI 2.93 to 11.60) compared to the matched control group. RTHC patients were also more likely to have had their first referral accepted (OR 2.78, 95% CI 1.29 to 6.73). Among patients with an accepted referral, RTHC patients were more likely to have attended an appointment (OR 3.86, 95% CI 1.90 to 8.57)., Conclusions: The results demonstrate that the RTHC model is successful in increasing access to specialty care by both increasing referral acceptance and appointment attendance., Competing Interests: The authors have no competing interests to declare., (Copyright: © 2022 The Author(s).)

Background: There is substantial variation in COVID-19 lethality across countries. In addition, in countries with populations with extreme economic inequalities, such as Mexico, there are regional and local differences in risk factors for COVID-19 death. The goal of this study was to test the hypothesis that the risk of death in Mexican COVID-19 patients was associated with the time between symptom onset and hospitalization and/or with the healthcare site. Also, death prognostic models were developed., Methods: The study included two COVID-19 inpatient cohorts, one prospective and one retrospective from Chiapas, Mexico. Demographic, clinical and laboratory variables were collected, and the diagnosis of SARS-CoV-2 infection was performed using RT-qPCR in samples collected seven days since symptom onset. The 30-day mortality, since symptom onset, was the outcome, and clinical variables at the first 48 hours of hospitalization were independent factors. Multivariate logistic regression analyses were conducted., Results: Of the 392 patients included, 233 died (59.4%). The time between symptom onset and hospitalization, the healthcare site and sex were not related to the 30-day mortality. Three death prognostic models were developed (AUC between 0.726 and 0.807). Age, LDH, AST, and lymphocyte count were included in all models, OSI-WHO Classification (Non-invasive ventilation or high-flow oxygen, and mechanical ventilation with or without organ support/ECMO) and leukocyte count in two models, and diabetes and diarrhea in one model., Conclusion: The population evaluated had underlying deteriorated health before COVID-19 compared with regional and country population. The factors that determine the COVID-19 mortality risk in a relatively healthy population are sex, age and comorbidities. However, as this study shows, when populations have underlying poor health, some of these factors lose their associations with mortality risk, and others become more important., Competing Interests: Competing interests The authors declare that they have no competing interest.

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease with an increased prevalence in Mexico. Although its etiology is unknown, its development can be influenced by environmental factors such as smoking and viral infections. But among the factors influencing susceptibility, it is the genetic factors that predominate, mainly the HLA-DRB1 genes, and specifically the alleles that have the shared epitope (SE). A transversal study was performed, in which 31 patients (28 women and 3 men) with RA, treated at the autoimmunity clinic of the High Specialty Hospital Ciudad Salud in Tapachula, Chiapas, southern México, were enrolled. Clinical, biochemical, and demographic data were analyzed; ESR (erythrocyte sedimentation rate), CRP (C-reactive protein), RF (rheumatoid factor), and ACPA (anticitrullinated peptide antibody) were recorded. All patients had at least one positive RA biological marker. For HLA alleles frequencies comparison, we enrolled ethnically matched healthy controls in a ratio of 3:1 for 25 cases and 4:1 for 6 cases in order to guarantee the balance between groups regarding the mean of age and proportion of gender (males vs females). HLA-DRB1*04 was found to be significantly increased in patients compared with ethnically matched healthy controls (p 0.0007, OR: 2.8, 95% CI 1.5-5.1); contrarily, DRB1*08 showed a protective effect (p 0.005, OR 0.1). This paper confirmed the involvement of HLA genes on risk determination for RA in a population of Mexican Mestizos from Tapachula, Chiapas. Key Points • HLA-DRB1*04 confirms the increased risk of rheumatoid arthritis. • HLA-DRB1*08 showed a more definite protective effect in southern Mexicans mestizos, a population with more Amerindian ancestry.