Background Influenza virus is responsible for 3 to 5 million cases every year with an estimated mortality in children around 0.15 deaths per 100,000 population. Mexico reported in the 2018–2019 Influenza season 7,210 confirmed cases with 811 deaths (11%) with AH1N1 the most frequent type with 67% of the cases and 88% of the deaths. Clinical assessment of children with influenza is difficult because of the overlap of symptoms between other viral diseases so we evaluated the severity of respiratory symptoms in influenza-positive and -negative children to attain better clinical assessment of influenza cases. Methods We evaluated 846 children less than 18 years old who were screened for influenza in the emergency department at our hospital by using the WHO Influenza Like Disease (ILD) definition between epidemiological week 40 up to week 20 of the 2018–2019 influenza season. Clinical characteristics, evolution and comorbidities were assessed between positive and negative influenza test. Influenza was confirmed by RT–PCR of a nasal swab. Both χ 2 test and t-test were used for statistical analysis of both groups. Results Of the 846 children evaluated for ILD, 177 were positive and 669 were negative for influenza virus. 53.6% of the positive group and 52.2% of the negative group were male, mean ages were 5.25 years and 3.73 years, respectively (P < 0.0001) with 55% and 73.9% less than 5 years old, respectively. 75.7% of the positive group had severe disease defined as hypoxemic pneumonia and 78.6% of the negative group. Statistically significant differences in clinical evaluation were observed regarding frequency of fever, cough, sore throat, chills, myalgias, arthralgias, malaise, conjunctivitis and sudden onset of symptoms. Also, in the positive group there was higher probability of having a positive close contact (6.8%) case than in the negative group (2.5%) (P = 0.005). Cardiopathy, immunosuppression and cancer were the most frequent comorbidities in the influenza group. Four percent of the influenza-positive group and 5% of the negative group were vaccinated. Influenza types were 55.4% AH1N1pdm09, 35% B (29% Yamagata, 22.6% Victoria, 48.4% undetermined) and 9% of AH3. Two deaths were reported in the influenza-positive group. Conclusions Influenza can produce a severe disease in children, especially with those with co-morbidity; therefore, careful evaluation of respiratory symptoms, contact history to ILD, and highly sensitive diagnostics will accurately diagnose influenza. Patients with severe influenza should be promptly treated with antivirals and isolated to decrease intrahospital transmission.

Un nuevo coronavirus, que causa el síndrome respiratorio agudo severo coronavirus 2 (SARS-CoV-2), surgió en China y se ha disparado en todo el mundo creando una pandemia. A finales de 2019 se detectaron e informaron varios casos de neumonía atípica de etiología desconocida, inicialmente en Wuhan, provincia de Hubei, China. Poco después, el Centro Chino para el Control y Prevención de Enfermedades identificó como agente causal al nuevo coronavirus de una muestra de hisopo de la garganta de un paciente y lo anunció, oficialmente, el 7 de enero de 2020. El virus se propagó rápidamente a más de 150 países. Entre el 31 de diciembre de 2019 y el 28 de febrero de 2020 se habían confirmado en el laboratorio 83,631 casos de COVID-19, y 2858 muertes. La superación de esta pandemia dependerá, en su mayor parte, de la disciplina que la población mundial tenga para respetar las reglas de convivencia, el distanciamiento social y, la única y mejor medida de prevención de casos en futuras temporadas, será mantener la guardia y no dejar de aplicar las medidas de prevención sugeridas.