The Omicron wave in Mexico: vaccine protection against progression to severe Covid-19 in SARS-CoV-2-infected workers.

OBJECTIVE: To assess the effectiveness of seven Covid-19 vaccines in preventing disease progression (DP) using data from national private sector workers during the Omicron wave in Mexico from January 2 to March 5, 2022. MATERIALS AND METHODS: This study employed an administrative retrospective cohort design, analyzing DP (hospitalization or death due to respiratory disease) among workers who filed a respiratory short-term disability claim and tested positive for SARS-CoV-2. Risk ratios (RRadj) were estimated using Poisson regression models adjusted for various factors. RESULTS: Vaccinated individuals had a lower risk of hospitalization and death compared with unvaccinated individuals. The overall RRadj for hospitalization and death were 0.36 (95%CI 0.32, 0.41) and 0.24 (0.17, 0.33), respectively. When evaluating vaccines individually, the RRadj for hospitalization were as follows Pfizer BioNTech 0.27 (95%CI 0.22, 0.33), Moderna 0.29 (95%CI 0.15, 0.57), Sinovac 0.32 (95%CI 0.25, 0.41), AstraZeneca 0.39 (95%CI 0.34, 0.46), Sputnik 0.39 (95%CI 0.28, 0.53), CanSino 0.41 (95%CI 0.24, 0.7), and Janssen 0.53 (95%CI 0.39, 0.72). The RRadj for death were as follows: Pfizer BioNTech 0.12 (95%CI 0.07, 0.19), Sputnik 0.15 (95%CI 0.06, 0.38), Sinovac 0.29 (95%CI 0.16, 0.53), AstraZeneca 0.30 (95%CI 0.20, 0.44), CanSino 0.38 (95%CI 0.1, 1.4), and Janssen 0.50 (95%CI 0.26, 0.97). CONCLUSION: Covid-19 vaccines significantly reduced the risk of severe disease during the Omicron wave in Mexico.

Fraction of COVID-19 hospitalizations and deaths attributable to chronic diseases.

Evidence shows that chronic diseases are associated with COVID-19 severity and death. This study aims to estimate the fraction of hospitalizations and deaths from COVID-19 attributable to chronic diseases associated to poor nutrition and smoking among adults who tested positive to COVID-19 in Mexico. We analyzed 1,006,541 adults aged ≥20 who tested positive for COVID-19 from March 23 to December 5, 2020. Six chronic diseases were considered: obesity, chronic obstructive pulmonary disease (COPD), hypertension, diabetes, cardiovascular disease, and chronic kidney disease (CKD). We calibrated the database using a bias quantification method to consider undiagnosed disease cases. To estimate the total impact of multiple diseases, we defined a multimorbidity variable according to the number of diseases. Risks of hospitalization and death were estimated with Poisson regression models and used to calculate population attributable fractions (PAFs). Chronic diseases accounted for to 25.4% [95% CI: 24.8%-26.1%], 28.3% (95% CI: 27.8%-28.7%) and 15.3% (95% CI: 14.9%-15.7%) of the hospitalizations among adults below 40, 40-59, and 60 years and older, respectively. For COVID-19-related deaths, 50.1% (95% CI: 48.6%-51.5%), 40.5% (95% CI: 39.7%-41.3%), and 18.7% (95% CI, 18.0%-19.5%) were attributable to chronic diseases in adults under 40, 40-59, and 60 years and older, respectively. Chronic diseases linked to poor nutrition and smoking could have contributed to a large burden of hospitalization and deaths from COVID-19 in Mexico, particularly among younger adults. Medical and structural interventions to curb chronic disease incidence and facilitate disease control are urgently needed.

Leading causes of excess mortality in Mexico during the COVID-19 pandemic 2020-2021: A death certificates study in a middle-income country.

Background: The death toll after SARS-CoV-2 emergence includes deaths directly or indirectly associated with COVID-19. Mexico reported 325,415 excess deaths, 34.4% of them not directly related to COVID-19 in 2020. In this work, we aimed to analyse temporal changes in the distribution of the leading causes of mortality produced by COVID-19 pandemic in Mexico to understand excess mortality not directly related to the virus infection. Methods: We did a longitudinal retrospective study of the leading causes of mortality and their variation with respect to cause-specific expected deaths in Mexico from January 2020 through December 2021 using death certificate information. We fitted a Poisson regression model to predict cause-specific mortality during the pandemic period, based on the 2015-2019 registered mortality. We estimated excess deaths as a weekly difference between expected and observed deaths and added up for the entire period. We expressed all-cause and cause-specific excess mortality as a percentage change with respect to predicted deaths by our model. Findings: COVID-19 was the leading cause of death in 2020-2021 (439,582 deaths). All-cause total excess mortality was 600,590 deaths (38⋅2% [95% CI: 36·0 to 40·4] over expected). The largest increases in cause-specific mortality, occurred in diabetes (36·8% over expected), respiratory infections (33·3%), ischaemic heart diseases (32·5%) and hypertensive diseases (25·0%). The cause-groups that experienced significant decreases with respect to the expected pre-pandemic mortality were infectious and parasitic diseases (-20·8%), skin diseases (-17·5%), non-traffic related accidents (-16·7%) and malignant neoplasm (-5·3%). Interpretation: Mortality from COVID-19 became the first cause of death in 2020-2021, the increase in other causes of death may be explained by changes in the health service utilization patterns caused by hospital conversion or fear of the population using them. Cause-misclassification cannot be ruled out. Funding: This study was funded by Conacyt.