The coronavirus disease 2019 (COVID-19) pandemic profoundly disrupted the epidemiology of respiratory viruses, driven primarily by widespread non-pharmaceutical interventions (NPIs) such as social distancing and masking. This eight-year retrospective study examines the seasonal patterns and incidence of influenza virus, respiratory syncytial virus (RSV), and other respiratory viruses across pre-pandemic, pandemic, and post-pandemic phases in Jalisco, Mexico. Weekly case counts were analyzed using an interrupted time series (ITS) model, segmenting the timeline into these three distinct phases. Significant reductions in respiratory virus circulation were observed during the pandemic, followed by atypical resurgences as NPIs were relaxed. Influenza displayed alternating subtype dominance, with influenza A H3 prevailing in 2022, influenza B surging in 2023, and influenza A H1N1 increasing thereafter, reflecting potential immunity gaps. RSV activity was marked by earlier onset and higher intensity post-pandemic. Other viruses, including human rhinovirus/enterovirus (HRV/HEV) and parainfluenza virus (HPIV), showed altered dynamics, with some failing to return to pre-pandemic seasonality. These findings underscore the need for adaptive surveillance systems and vaccination strategies to address evolving viral patterns. Future research should investigate the long-term public health implications, focusing on vaccination, clinical outcomes, and healthcare preparedness.

This study investigates the relationship between SARS-CoV-2 RT–PCR cycle threshold (Ct) values and key COVID-19 transmission and outcome metrics across five years of the pandemic in Jalisco, Mexico. Utilizing a comprehensive time-series analysis, we evaluated weekly median Ct values as proxies for viral load and their temporal associations with positivity rates, reproduction numbers (Rt), hospitalizations, and mortality. Cross-correlation and lagged regression analyses revealed significant lead–lag relationships, with declining Ct values consistently preceding surges in positivity rates and hospitalizations, particularly during the early phases of the pandemic. Granger causality tests and vector autoregressive modeling confirmed the predictive utility of Ct values, highlighting their potential as early warning indicators. The study further observed a weakening association in later pandemic stages, likely influenced by the emergence of new variants, hybrid immunity, changes in human behavior, and diagnostic shifts. These findings underscore the value of Ct values as scalable tools for public health surveillance and highlight the importance of contextualizing their analysis within specific epidemiological and temporal frameworks. Integrating Ct monitoring into surveillance systems could enhance pandemic preparedness, improve outbreak forecasting, and strengthen epidemiological modeling.

The coronavirus disease 2019 (COVID-19) pandemic profoundly disrupted respiratory virus epidemiology through widespread non-pharmaceutical interventions (NPIs), such as mask-wearing and social distancing. This retrospective study explores the seasonal patterns and incidence of influenza virus, respiratory syncytial virus (RSV), and other respiratory viruses over an eight-year period in Jalisco, Mexico, to understand shifts in virus circulation across the prepandemic, pandemic, and postpandemic phases. Weekly case counts were analyzed using an interrupted time series (ITS) model, segmenting the timeline into these three distinct phases. The ITS results revealed abrupt reductions in viral incidence during the pandemic, followed by notable resurgences as NPIs were relaxed. Influenza A (H3) predominated in 2022, while influenza B surged in 2023, and Influenza A H1N1 cases increased subsequently. RSV exhibited an earlier onset and heightened activity compared to prepandemic trends. Other viruses, including human enterovirus/rhinovirus and human parainfluenza virus, showed altered patterns, with some failing to return to prepandemic seasonality. These findings highlight the complex interplay between viral ecology and population immunity, influenced by pandemic-related behavioral shifts. The results underscore the need for adaptive surveillance systems and targeted vaccination strategies to address evolving respiratory pathogen dynamics and mitigate future public health impacts.

Measles resurgence threatens elimination achievements in the Americas. We conducted a nationwide analysis of Mexico’s 2025–2026 measles outbreak, integrating individual-level surveillance data from the Special Surveillance System for Febrile Exanthematous Diseases with municipal-level social determinants from eight national databases, complemented by molecular surveillance data. We analyzed 6892 confirmed cases using spatial autocorrelation (Moran’s I and LISA), effective reproduction number estimation, logistic regression models for municipal case presence, and multivariable logistic regression for risk factors for complications. Cases concentrated in Chihuahua (65.2%), with 47 LISA hot-spot municipalities containing 64.4% of cases. Molecular surveillance confirmed two independent introductions: D8/MVs/Ontario.CAN/47.24 (98.1%), linked to the North American outbreak, and B3 (1.9%) in Oaxaca. Transmission followed a three-stage pattern: introduction through seasonal agricultural worker networks, amplification in undervaccinated communities, and diffusion to marginalized indigenous populations. A dual-model analysis revealed that school non-attendance among children aged 6–14 years may have mediated the effect of very high marginalization on municipal case presence (OR 1.26; p < 0.001), identifying a potentially actionable vaccination pathway. Vaccine effectiveness was 98.1%, confirming susceptible accumulation rather than vaccine failure. Wave-stratified analysis showed late outbreak phase as an independent risk factor for complications (aOR 1.68, 95% CI: 1.42–2.00), converging with an age of <1 year (aOR 3.36), indigenous status (aOR 1.89), and unvaccinated status (aOR 1.96) in the most marginalized communities. Indigenous individuals comprised 29.1% of cases but 76% of the 25 deaths. This outbreak demonstrates that national vaccination thresholds are insufficient when municipal pockets of susceptibility remain systematically underserved.

Scientific articles are an essential tool in the world of research and science. They are a way for researchers to share their findings with the scientific community and the general public. In addition, they are an important source of information and knowledge in different fields of study. This book will discuss the challenges associated with writing scientific articles and how to overcome them to achieve success in the world of research. Tips and resources will also be provided to help researchers improve their science writing skills. Los artículos científicos son una herramienta esencial en el mundo de la investigación y la ciencia. Son una forma en que los investigadores pueden compartir sus hallazgos con la comunidad científica y el público en general. Además, son una fuente importante de información y conocimiento en diferentes campos de estudio. En este libro se discutirán los desafíos asociados con la escritura de artículos científicos y cómo superarlos para lograr el éxito en el mundo de la investigación. También se brindarán consejos y recursos para ayudar a los investigadores a mejorar sus habilidades de escritura científica.

Measles resurgence threatens elimination achievements in the Americas. We conducted a nationwide analysis of Mexico's 2025 measles outbreak, integrating individual-level surveillance data from the Special Surveillance System for Febrile Exanthematous Dis-eases with municipal-level social determinants from eight national databases, comple-mented by molecular surveillance data. We analyzed 6151 confirmed cases (epidemio-logical weeks 8–52, 2025) using spatial autocorrelation (Moran’s I, LISA), effective re-production number estimation, negative binomial regression, and logistic regression for risk factors. Cases concentrated in Chihuahua (73%), with 45 LISA hot-spot municipalities containing 71.68% of cases. Molecular surveillance confirmed two independent intro-ductions: D8/MVs/Ontario.CAN/47.24 (98.1%) linked to the Canadian outbreak, and B3 (1.9%) in Oaxaca. Transmission followed a three-stage pattern: introduction through seasonal agricultural worker networks, amplification in undervaccinated communities, and diffusion to marginalized indigenous populations. Vaccine effectiveness was 98.2%, with 83.4% of cases in pockets of susceptibles (municipalities with ≥80% unvaccinated). Risk factors for complications included age < 5 years (aOR 3.59), indigenous status (aOR 2.35), and unvaccinated status (aOR 2.03). Indigenous individuals comprised 30% of cases but 76% of deaths. This outbreak demonstrates that national vaccination thresholds are insufficient when marginalized populations remain systematically underserved.