Overview

Influenza, commonly known as the flu, is an acute viral respiratory infection caused by influenza viruses. It is highly contagious and affects millions globally each year, causing seasonal epidemics and occasional pandemics. The flu presents with a sudden onset of fever, cough, body aches, and fatigue, and can lead to severe complications, particularly in vulnerable populations. In Korea, comprehensive vaccination programs, rapid diagnostic testing, and effective antiviral treatments are employed to manage influenza and reduce its impact on public health.

What Is Influenza (Flu)?

Influenza is caused primarily by three types of influenza viruses: A, B, and C, with types A and B responsible for most human infections. The virus spreads through respiratory droplets when infected people cough or sneeze and via contact with contaminated surfaces. Symptoms typically develop within 1-4 days of exposure and last about a week but can persist longer in some cases. The flu can affect people of all ages and leads to significant morbidity and mortality annually.

Symptoms

• Sudden high fever
• Dry cough and sore throat
• Runny or stuffy nose
• Muscle and joint aches
• Headache
• Fatigue and weakness
• Chills and sweating
• Occasionally nausea, vomiting, and diarrhea (more common in children)

Causes

Influenza viruses infect the respiratory tract lining and rapidly replicate, causing inflammation and damage to the mucosa. The infection disrupts normal respiratory function and triggers immune responses that produce systemic symptoms. The viruses mutate frequently, leading to new strains that evade immune memory and cause recurrent outbreaks.

Risk Factors

• Young children and elderly adults (especially over 65 years)
• Individuals with chronic medical conditions such as asthma, diabetes, heart disease, or immunosuppression
• Pregnant women
• Healthcare workers and caregivers with frequent exposure
• Residents of long-term care facilities
• Crowded living conditions

Complications

• Pneumonia, either viral or secondary bacterial infection
• Exacerbation of chronic respiratory and cardiac conditions
• Dehydration and worsening of underlying diseases
• Hospitalization and increased risk of death in vulnerable groups
• Rare neurological complications like encephalitis or Guillain-Barré syndrome

Prevention

• Annual influenza vaccination, updated to match circulating strains
• Good hand hygiene and respiratory etiquette (covering coughs and sneezes)
• Avoiding close contact with infected individuals
• Use of masks during outbreaks or in crowded places
• Prompt antiviral treatment when indicated to reduce severity and spread

Treatment Options in Korea

Korean healthcare institutions offer a comprehensive approach to influenza management:

• Vaccination:
  • Nationwide seasonal flu vaccination campaigns targeting high-risk groups and the general population
  • Use of quadrivalent vaccines covering multiple influenza strains
• Diagnostic Testing:
  • Rapid antigen tests and PCR assays for early and accurate diagnosis
• Antiviral Medications:
  • Neuraminidase inhibitors like oseltamivir and zanamivir prescribed to reduce illness duration and prevent complications, especially if started early
  • Supportive care including hydration, fever control, and rest
• Public Health Measures:
  • Surveillance programs to monitor circulating strains and vaccine effectiveness
  • Educational campaigns promoting vaccination and hygiene practices
  • Infection control protocols in hospitals and public settings

Korea’s advanced medical infrastructure and proactive public health strategies contribute to effective influenza control, minimizing disease burden and protecting vulnerable populations.