October 2019
Flu alert: ‘Tis the seasonInfluenza season is coming. For some of us, it might have already arrived. Either way, you need to be prepared. The 2018-19 influenza season was moderately severe, lasting 21 weeks- the longest season in the past decade. There were 116 laboratory-confirmed pediatric deaths (median age of 6 years), with nearly half in previously healthy children. Most of the deaths had not been vaccinated against the flu. For the 2019-20 influenza season, the American Academy of Pediatrics (AAP) continues to urge annual vaccination for everyone six months and older, and they also included seven main updates in their recent policy statement that is listed in the references below. Emergency Physicians are familiar with the wide variety of symptoms that patients with influenza can present with. It is essential to distinguish specific groups who are at high risk of developing complications secondary to influenza. Those at high risk for complications include adults and children with pre-existing pulmonary conditions like Chronic Obstructive Pulmonary Disease (COPD), asthma, cystic fibrosis, or interstitial lung disease. Patients with diabetes, morbid obesity, hepatic or renal disease, immunodeficiency, or pregnancy are also at high risk. About 90% of deaths occur in people greater than 65 years of age. Children who are younger than two years of age and have chronic medical conditions also have a high risk of mortality related to influenza. When it comes to testing for the virus, we are all familiar with the commercially available rapid antigen tests found in most Emergency Departments. It is important to mention that these rapid influenza diagnostic testing kits have a low sensitivity for detecting the virus (anywhere between 50-70%) and a specificity of 90-95%. This can lead to many false negative results. If the prevalence of influenza is high; especially during peak months, diagnosis of the disease should be based on clinical judgment and patient’s presentation. More definitive testing through PCR or viral cultures should be saved for critically ill patients who will be admitted to the hospital to avoid exposing other patients in the hospital who are not infected with influenza. The recommendations for the antivirals- neuraminidase inhibitors (NAIs) such as oseltamivir, zanamivir, peramivir; and the selective inhibitor of influenza cap-dependent endonuclease (baloxavir)- are all the same. Most patients don’t need them. The best results are observed within 48 hours of symptom onset. However, consider initiating antiviral therapy beyond that in children with severe or progressive disease or a high risk of complications, and all patients hospitalized for influenza. Finally, it is important to consider other life-threatening conditions that may mimic ‘the flu.’ Avoid anchoring bias by keeping a broad list of differential diagnoses that include; myocarditis, endocarditis, spinal epidural abscess, or even necrotizing soft tissue infection. Mohamed Hagahmed, MD References: - Recommendations for Prevention and Control of Influenza in Children, 2019–2020 - Uyeki, T. Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenza. Clinical Infectious Diseases, Volume 68, Issue 6. |
