What are the potential complications following influenza (flu) infection?

From the Guidelines

Influenza infection can lead to various complications, including respiratory issues such as acute bronchitis, primary viral pneumonia, and secondary bacterial pneumonia, as well as cardiovascular, muscular, and central nervous system problems, with the risk of complications being higher in certain groups, such as the elderly, young children, and those with underlying medical conditions. The potential complications of influenza infection are numerous and can be categorized into several groups, including:

• Respiratory complications, such as:
  • Acute bronchitis, which is more common in the elderly and those with chronic medical conditions 1
  • Primary viral pneumonia, which typically occurs within 48 hours of the start of fever 1
  • Secondary bacterial pneumonia, which usually occurs four to five days after the onset of illness 1
• Cardiovascular complications, such as:
  • ECG abnormalities, which are common but often not associated with cardiac symptoms 1
  • Myocarditis and pericarditis, which are rare 1
• Muscular complications, such as:
  • Myositis, which occurs during early convalescence and is uncommon 1
  • Myoglobinuria and renal failure, which are rare 1
• Central nervous system complications, such as:
  • Encephalitis/encephalopathy, which is rare and more common in children and in Japan 1
  • Transverse myelitis and Guillain Barré syndrome, which are very rare 1 Other potential complications of influenza infection include otitis media, toxic shock syndrome, and parotitis 1. It is essential to note that certain groups, such as the elderly, young children, and those with underlying medical conditions, are at a higher risk of developing complications from influenza infection 1. Therefore, it is crucial to take preventive measures, such as vaccination, and to seek medical attention if symptoms persist or worsen over time.

From the Research

Potential Complications of Influenza Infection

The potential complications of influenza infection can be severe and include:

• Lower respiratory tract complications requiring antibiotics 2
• Admittance to hospital for any cause 2
• Acute respiratory distress syndrome (ARDS) 3
• Increased morbidity and mortality in certain populations, such as the very young, individuals with chronic comorbid conditions, immunocompromised individuals, pregnant women, and frail older adults 4

High-Risk Populations

Certain populations are at a higher risk of developing complications from influenza infection, including:

• Very young individuals 4
• Individuals with chronic comorbid conditions 4
• Immunocompromised individuals of all ages 4
• Pregnant women 4
• Frail older adults 4

Management and Prevention

Antiviral medications, such as oseltamivir, can help alleviate symptoms and reduce the risk of complications 2 Vaccination is the primary preventive measure against influenza and is recommended for all people 6 months of age or older, unless contraindicated 5