Clinical management of flu

Under normal conditions, a prescription is rarely necessary.

The following guidance is recommended:

• Treat fever, headaches, generalised aches and pains with paracetamol or ibuprofen (aspirin is contraindicated in children aged under 16 years)
• Advise plenty of fluids to avoid dehydration
• Advise rest and keeping warm
• Recommend segregation from vulnerable people
• Advise abstinence from smoking
• Advise against flying (change in air pressure can further stress the respiratory system. Flying with cold or flu congestion can temporarily damage the eardrums as a result of pressure changes during takeoff and landing)
• Recommend sufficient time for recovery, usually around 5-7 days

With concomitant chronic diseases

Existing chronic health conditions can exacerbate flu, leading to serious complications. On the other hand, flu itself can aggravate chronic health issues.

The following chronic conditions pose as risk factors for the development of flu-related complications, such as pneumonia, and sinus and ear infections in the elderly and those with compromised immune system:

• Diabetes: This includes people suffering from both type 1 and type 2 diabetes. Flu can affect blood sugar levels and trigger dangerous spikes and/or drops. People with diabetes typically suffer from a weaker immune system, which means that even minor infections can rapidly become life-threatening.
• Asthma, chronic lung disease and COPD: People with chronic respiratory conditions are more susceptible to flu complications due to their already compromised lung function. Any respiratory infection, including flu, can cause inflammation and restrict the airway, making it difficult to breathe and get adequate oxygen. This inflammation can lead to an increase in asthma attacks and COPD exacerbations. In fact, adults with asthma are more likely to develop pneumonia after contracting flu than those without.
• Heart disease: Underlying heart conditions are not thought to necessarily increase the elderly’s risk of contracting flu. However, they can augment the risk of complications. Individuals with heart disease, congenital heart defects, congestive heart failure, coronary artery disease and a history of stroke who contract flu have an elevated risk of heart attack and stroke, which can be fatal.
• Kidney disorders: Chronic kidney disease can weaken the body’s ability to fight off infections like flu. Consequently, flu can exacerbate symptoms of kidney disease and damage these vital organs. It is possible that recipients of a kidney transplant end up rejecting the new kidney if they contract flu.
• Liver disorders: Just like in individuals with limited renal function, the flu can exacerbate liver disease. Flu can also cause the body to reject a transplanted liver. The therapies that people with liver and kidney disease can take to counteract flu virus are limited since most of the drugs are metabolized by the two organs. If the kidney and liver are already compromised, then taking certain medications can cause additional harm.
• Neurological conditions: Health problems like epilepsy, Parkinson’s disease, history of stroke and Huntington’s disease can weaken the body’s ability to fight off the flu.
• Cancer and HIV: Any disease or treatment plan that causes a weakened immune system, such as HIV and chemotherapy for cancer treatment, can increase a person’s likelihood of contracting the flu and developing related and sometimes, life-threatening complications.

Influenza antiviral drugs can be used both for prevention as well for management of influenza.

• Available antiviral medications, such as oral oseltamivir phosphate (available under the trade name of Tamiflu), inhaled zanamivir (trade name Relenza), and intravenous peramivir (trade name Rapivab), function as neuraminidase inhibitors, which block the viral neuraminidase enzyme and are effective against both influenza A and B viruses.
• Early antiviral treatment can shorten the duration of symptoms, reduce the risk of some complications from influenza (e.g., otitis media in young children, pneumonia, and respiratory failure), shorten the duration of hospitalization and reduce deaths in hospitalised patients. The greatest clinical benefit is observed when antiviral medication is initiated early, especially within 48 hours of symptoms onset.
• It is recommended to start antiviral treatment as early as possible for any patient with confirmed or suspected influenza who:
• is hospitalized
• has severe, complicated, or progressive illness or
• is at higher risk for influenza complications

Antiviral medications are recommended in people at higher risk of complications and with concomitant chronic conditions as described above. The high-risk group also includes the elderly (over 65) and residents of care/nursing homes, pregnant women or those in post-partum (within two weeks after delivery), babies under 6 months of age, people who are immunocompromised or immunosuppressed and those with a BMI of ≥40.

Initiation of antiviral treatment should not be delayed while awaiting laboratory confirmation of influenza. The recommended schedule of oral oseltamivir or inhaled zanamivir is one dose twice a day for 5 days. Pregnant women should be treated with oral oseltamivir at the same dose and duration.

Author: Dr Reshma Ramracheya is a group leader at the University of Oxford with over 18 years of experience in teaching and medical research.

Reference:

• Hay AJ, McCauley JW. The WHO global influenza surveillance and response system (GISRS)—A future perspective. Influenza Other Respi Viruses. 2018;12:551–557. https://doi.org/10.1111/irv.12565.
• Hemila H., Chalker E., Douglas B. The Cochrane Library; 2010.
• Sabbaghi A, Miri SM, Keshavarz M, Zargar M, Ghaemi A. Inactivation methods for whole influenza vaccine production. Rev Med Virol. 2019 Jul 23:e2074. doi: 10.1002/rmv.2074.
• CDC, Centers for Disease Control and Prevention (https://www.cdc.gov/vaccines/pubs/pinkbook/flu.html)
• NICE, National Institute for Health and Care (https://www.nice.org.uk/guidance/conditions-and-diseases/infections/influenza)