ABSTRACT
PURPOSE: The Omicron subvariant BA.1 of SARS-CoV-2 was first detected in November 2021 and quickly spread worldwide, displacing the Delta variant. In this work, a characterization of the spread of this variant in Mexico is presented. METHODS: The time to fixation of BA.1, the diversity of Delta sublineages, the population density, and the level of virus circulation during the inter-wave interval were determined to analyze differences in BA.1 spread. RESULTS: BA.1 began spreading during the first week of December 2021 and became dominant in the next three weeks, causing the fourth COVID-19 epidemiological surge in Mexico. Unlike previous variants, BA.1 did not exhibit a geographically distinct circulation pattern. However, a regional difference in the speed of the replacement of the Delta variant was observed. CONCLUSIONS: Viral diversity and the relative abundance of the virus in a particular area around the time of the introduction of a new lineage seem to have influenced the spread dynamics, in addition to population density. Nonetheless, if there is a significant difference in the fitness of the variants, or if the time allowed for the competition is sufficiently long, it seems the fitter virus will eventually become dominant, as observed in the eventual dominance of the BA.1.x variant in Mexico.
Subject(s)
COVID-19 , Epidemics , Humans , Mexico/epidemiology , COVID-19/epidemiology , SARS-CoV-2/geneticsABSTRACT
PURPOSE: In the last two decades transmission of hepatitis C virus (HCV) in HIV positive men who have sex with men (MSM) has been reported globally. Chemsex and specific sexual practices have been identified as risk factors. Our study aimed to identify risk factors for HCV transmission in MSM living with HIV attending in Mexico. METHODS: We conducted a case-control study from April to December 2019 at the Hospital de Infectología "La Raza" National Medical Center, in Mexico City. A case was defined as an HIV-infected MSM with positive HCV-antibody test. For each case, 3 controls were included, defined as HIV infected MSM with negative HCV-antibody test. A self-questionnaire covering sexual practices and other risk factors for HCV transmission was applied. Bivariate analysis was performed to obtain odds ratio (OR) using Chi-square test. Independent risk factors were identified in a subsequent analysis performing a logistic regression model. RESULTS: A total of 324 patients participated in the study, 81 cases and 243 controls. Median age was 30.5 years (IQR: 18-52) and 28.8 years (IQR: 21-45) in the case and control group, respectively. Most prevalent HCV genotype was 1a (79%). In the logistic regression model, sharing straw during cocaine inhalation (OR: 9.03; 95% CI; 1.35-13.52; P = 0.003), sharing sex toys (OR: 17.53, 95% CI; 6.85-44.86; P = 0.002), and ethyl chloride use for chemsex (OR: 2.26; 95% CI; 1.29-5.56; P = 0.037) were significant risk factors for HCV infection. CONCLUSION: This study identifies risk factors for HCV transmission in Mexico in HIV positive MSM in congruence with the findings of many studies performed worldwide. This is the first study that indicates a possible association between ethyl chloride use in chemsex and HCV infection. Assessment of local populations for risk factors for HCV transmission may help to develop specifically targeted behavioral interventions to reduce HCV transmission.