Since the beginning of the SARS-CoV-2 pandemic healthcare professionals have found it necessary to generate diagnostic methods for the disease that are easy to use, reliable, and accessible. The Berlin-Charité protocol has been one of the most recommended methods for detecting SARS-CoV-2 from the onset of the pandemic. However, new diagnostic techniques such as GeneXpert have been developed and proven to be efficient, fast, and easy to use to detect infected patients. The purpose of this study, conducted at the National Institute for Respiratory Diseases in Mexico, was to compare the diagnostic performance of the Berlin-Charité protocol and GeneXpert for the detection of SARS-CoV-2, evaluating a cohort of 135 Mexican patients. For statistical analysis, sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratios for each assay were calculated. The diagnostic parameters for GeneXpert were found to be 100% in both sensitivity and specificity. The Berlin-Charité protocol performance had a sensitivity of 72% and specificity of 100%. With this study, it can be concluded that the diagnosis of SARS-Cov_2 infection through GeneXpert was 29% more specific than the Berlin protocol.

Introduction: Respiratory Syncytial Virus (RSV) is the main causative agent of respiratory tract infections at pediatric ages in Mexico and around the world. In our study we determine and correlating clinics characteristics to the levels of specific IgA against RSV in respiratory samples for infected children and the absence or presence of exclusive breastfeeding. Material and methods: This is a clinical, ambispective and comparative study. There were included all patients pediatrics hospitalized and the samples of nasopharyngeal exudate were obtained, there was performed an ELISA on them with a Human Respiratory Syncytial Virus to determine the levels of specific IgA against RSV. Results: The total of patients included was 197. Finding that only 4.1% of infants received a complete vaccination schedule. Up to 22.8% were coinfected with a virus upon admission. There was found a significant difference in the rate of oxygenation during the admission presented by lactated vs non-lactated patients (p 0.002), as well as the presence of crackles p = 0.029 (95% CI 0.502-0.095) and wheezing p = 0.043 (95% CI 0.522-0.980), and a difference between the levels of specific IgA and the personal history of repeated respiratory tract infections (p = 0.018). Differences in symptoms such as dry cough, thoracoabdominal dissociation (p = 0.043, p = 0.044 respectively), were found as well. Conclusions: The results obtained from this research lead to stablish that low levels of specific IgA against RSV in the airways, are statistically and clinically related to greater severity of RSV infection.