Clinical spectrum, risk factors, and outcomes of children with laboratory-confirmed influenza infection managed in a single tertiary hospital

Acute respiratory infections (ARIs) are major contributors to morbidity and mortality worldwide. Influenza, a vaccine‐preventable disease, is a significant cause of ARI, affecting annually 5% to 10% of the population globally and causing morbidity and mortality, especially in high‐risk groups such as children. 1 It causes approximately one million influenza‐associated hospitalizations among children younger than 5 years of age and 500 000 deaths among all age groups. 2 , 3

Different strains of influenza exist and include type A, B, and C. Type A and B can cause outbreaks and epidemics in humans; accordingly, circulating strains of both types are incorporated in seasonal influenza vaccines. 4 , 5 Human influenza infection is most commonly caused by type A virus, which is the only type known to cause pandemics. 6 , 7 Transmission of the influenza virus occur through the respiratory droplets, and it tends to increase during the winter season in countries with temperate climates, often severely impacting healthcare services. 1

Symptoms of influenza infection include fever, sore throat, nasal discharge, headache, myalgia, cough, vomiting, and diarrhea. 8 Complications are not uncommon and remain a public health concern. They include pneumonia, acute respiratory failure, acute respiratory distress syndrome (ARDS), otitis media, febrile seizure, encephalitis/encephalopathy, myositis, rhabdomyolysis, myocarditis, renal failure, multi‐organ failure, and can lead to death. 9 , 10 , 11 , 12

The wide spectrum of the clinical presentation 13 with ill‐defined signs and symptoms often leads to empirical management without respiratory sampling. Such practice makes it difficult to estimate the true burden of influenza. 14 Quantifying the latter is required to reveal the pattern of illness severity and guide public health policies. It is also needed to justify the seasonal influenza vaccination, 9 which remains the key preventive intervention for influenza‐related hospitalizations and deaths, and assess its impact. 15

Seasonal influenza vaccine was started in the United Arab Emirates in 2006 for high‐risk healthcare professionals and people with chronic illnesses. Since 2012, elderly (>65 years) were added to the high‐risk groups, and in 2015, all community members were encouraged (but not mandated) to receive the vaccine including infants >6 months. The trivalent seasonal vaccine contains influenza A(H1N1), A(H3N2), and influenza B strain (Colorado), while the tetravalent vaccine has, in addition, the Phuket strain (an additional B strain). In our center, a trivalent vaccine was given to all children >6 months of age, while children with certain comorbidities received the tetravalent vaccine. Those comorbidities include: Chronic lung dieses, asthma, congenital heart disease, and patients on immunosuppressant medications.

The existing literature on influenza infection among the pediatric population in the United Arab Emirates is scarce. 16 Thus, we conducted this study to estimate the demographic, clinical features, laboratory findings, and the outcomes of children with confirmed influenza virus infection who presented to a tertiary hospital in Al Ain City in the United Arab Emirates over a 6‐year period, and the relationship to their seasonal influenza vaccination status.

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