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.

IntroductionAt the end of 2015, the first cases of Zika were identified in southern Mexico. During 2016, Zika spread as an outbreak to a large part of the country's coastal zones.MethodologyThe Zika epidemiological surveillance system records cases with clinical symptoms of Zika virus disease (ZVD) and those confirmed by means of a reverse polymerase chain reaction (RT-PCR) assay. This report includes the suspected and confirmed cases from 2016. Incidence rates were estimated by region and in pregnant women based on the proportion of confirmed cases.ResultsIn total, 43,725 suspected cases of ZVD were reported. The overall incidence of suspected cases of ZVD was 82.0 per 100,000 individuals and 25.3 per 100,000 Zika cases. There were 4,168 pregnant women with suspected symptoms of ZVD, of which infection was confirmed in 1,082 (26%). The estimated incidence rate of ZVD for pregnant women nationwide was 186.1 positive Zika cases per 100,000 pregnant women.ConclusionsThe incidence of Zika in Mexico is higher than that reported previously in the National System of Epidemiological Surveillance. Positive cases of Zika must be estimated and reported.

BackgroundTuberculosis and HIV remain a public health problem in developed countries. The objective of this study was to analyze the incidence trends of pulmonary TB and HIV comorbidity and treatment outcomes according to HIV during the period 2006 to 2014 in the Mexican Institute of Social Security.MethodsAnalyzed data from this registry including pulmonary tuberculosis patients aged 15 years and older who had been diagnosed during the years 2006 to 2014 in the Mexican Institute of Social Security. The outcomes that we use were incidents rate, failure to treatment and death. Regression models were used to quantify associations between pulmonary tuberculosis and HIV mortality.ResultsDuring the study period, 31,352 patients were registered with pulmonary tuberculosis. The incidence rate observed during 2014 was 11.6 case of PTB per 100,000. The incidence rate for PTB and HIV was 0.345 per 100,000. The PTB incidence rate decreased by 0.07%, differences found in the PTB incidence rate by sex since in women decreased by 5.52% and in man increase by 3.62%. The pulmonary TB with HIV incidence rate decreased by 16.3% during the study period (In women increase 4.81% and in man decrease 21.6%). Analysis of PTB associated with HIV by age groups revealed that the highest incidence rates were observed for the 30 to 44 years old group. Meanwhile, the highest incidence rates of PTB without HIV occurred among the 60 and more years old individuals. We did not find statistically significant differences between treatment failure and PTB patients with HIV and without HIV. The treatment failure was associated with sex and the region of the patient. We found a strong association between HIV and the probability of dying during treatment. Our data suggested that patients suffering from both conditions (PTB and HIV) have no difference in the probability of failure of treatment contrary to other reports. Hypotheses to this is adherence to tuberculosis treatment with people living with HIV/AIDS, detection of PTB in patients suffering from HIV/AIDS or PTB patients on antiretroviral therapy were more likely to have successful treatment outcomes than those not on antiretroviral treatment. We have found that PTB and HIV increases the probability of dying during treatment compared to the cases of PTB without HIV, consistent with published other study HIV increases the mortality rates associated with PTB.ConclusionsNo association between pulmonary tuberculosis with HIV and treatment failure was observed, but pulmonary tuberculosis and HIV increases the probability of dying during treatment compared to the pulmonary tuberculosis cases without HIV.

The Dengue (DENV), Zika (ZIKV), and Chikungunya (CHIKV) virus infections have been linked to Guillain-Barré syndrome (GBS). GBS has an estimated lethality of 4% to 8%, even with effective treatment. Mexico is considered a hyperendemic country for DENV due to the circulation of four serotypes, and the ZIKV and CHIKV viruses have also been circulating in the country. The objective of this study was to predict the number of GBS cases in relation to the cumulative incidence of ZIKV / DENV / CHIKV in Mexico from 2014 to 2019. A six-year time series ecological study was carried out from GBS cases registered in the Acute Flaccid Paralysis (AFP) Epidemiological Surveillance System (ESS), and DENV, ZIKV and CHIKV estimated cases from cases registered in the epidemiological vector-borne diseases surveillance system. The results shows that the incidence of GBS in Mexico is positively correlated with DENV and ZIKV. For every 1,000 estimated DENV cases, 1.45 GBS cases occurred on average, and for every 1,000 estimated ZIKV cases, 1.93 GBS cases occurred on average. A negative correlation between GBS and CHIKV estimated cases was found. The increase in the incidence of GBS cases in Mexico can be predicted by observing DENV and ZIKV cases through the epidemiological surveillance systems. These results can be useful in public health by providing the opportunity to improve capacities for the prevention of arbovirus diseases and for the timely procurement of supplies for the treatment of GBS.

Objectives The objective of this study is to estimate the effectiveness of COVID-19 vaccines in people treated within the social security system whose vaccination status was reported to the epidemiological surveillance system. Study design Case-control study. Methods This was a case-control study conducted. The records of individuals with suspected cases of COVID-19 registered in the epidemiological surveillance system between February 1 and June 30, 2021, were studied. RT–qPCR was performed to determine SARS-CoV-2 infection; those with a positive result were considered cases, and those with a negative result were considered controls. The ratio between cases and controls was 1:1.3. The crude and adjusted vaccine effectiveness was considered the prevention of symptomatic infection and death and calculated as the difference between the dose and the risk, with a survival analysis among vaccinated people. Results A total of 94,416 individuals were included, of whom 40,192 were considered cases and 54,224 controls; 3,781 (4.00%) had been vaccinated against COVID-19. Vaccination also proved to be a protective factor against COVID-19, especially in the population who received a second dose (OR = 0.31; 95% CI 0.28–0.35). With the application of the vaccine, there was a protective effect against mortality (OR = 0.76; 95% CI 0.66–0.87). Disease prevention was higher for the BNT162-2 mRNA vaccine (82%) followed by the ChAdOx1 vaccine (33%). In the survival analysis, vaccination provided a protective effect. Conclusions There was a positive impact of vaccines for the prevention of symptomatic COVID-19, with a second dose generating greater efficacy and a reduction in deaths.