Clinical profile of children with influenza A and B infections admitted to a tertiary care hospital in South India

Background: The influenza pandemics have caused serious morbidity and mortality around the world. Only a few studies have described the clinical profile of both influenza A and B infections among children and its seasonal variations. Aims: To study the clinical profile of children with influenza (A and B) admitted to a tertiary care hospital in India over a period of 17 months. Methods: A retrospective case file review was done for all influenza-positive cases (by real time-polymerase chain reaction) admitted in the ward and pediatric intensive care unit of a tertiary care hospital from January 2018 to May 2019. Results: A total of 164 admitted children were screened for influenza, of which 41 children (25%) were positive. Seasonal variation showed highest peak in the month of October with 17 positive cases (41%). Influenza B was observed during the first half of the year 2018 followed by an increase in influenza A infection in the last 6 months. The common presenting symptoms were cough (16, 39%) and respiratory distress (21, 51%). Out of 41, 18 children (44%) required respiratory support, but only 2 (5%) required mechanical ventilation. Hyponatremia was present at admission in 13 (61%) of 21 (51%) tested samples. The median length of hospital stay in the admission hyponatremia group was 7 days (interquartile range [IQR] 4, 15) as compared to the overall median length of stay of 4 days (IQR 3, 7). Conclusions: Our study showed a predominance of influenza B in the first half of the year and influenza A infection during the second half. A similar pattern was also seen in the first half of the subsequent year. Further studies are required to understand the impact of hyponatremia in these patients.