About Influenza

The flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. It can cause mild to severe illness, and at times can lead to death.

There are three types of seasonal influenza – A, B and C. Type A influenza viruses are further typed into subtypes according to different kinds and combinations of virus surface proteins. Influenza A(H1N1) and A(H3N2) are subtypes of the virus that are currently circulating worldwide. Influenza A(H1N1) can be fatal to humans.

Preventing Transmission

  • Cover your nose and mouth when coughing and sneezing
  • Always wash hands with soap and water
  • Use alcohol-based hand sanitizers
  • Avoid close contact with sick peopleHealth-care-acquired pneumonia – difficult-to-treat bacterial pneumonia acquired in health care facilities
  • Inhalation or aspiration pneumonia – occurs when you breathe foreign matter into your lungs
  • Opportunistic viral, bacterial and fungal pneumonias -strikes people with weakened immune systems

Signs and Symptoms

  • Fever or feeling feverish/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Fatigue (tiredness)
  • Some people may have vomiting and diarrhea, though this is more common in children than adults.
  • It’s important to note that not everyone with flu will have a fever.


  • Most people who get influenza will recover in a few days to less than two weeks, but some people will develop complications, some of which can be life-threatening and result in death. Pneumonia, bronchitis, and sinus and ear infections are three examples of complications from flu.

People at High Risk

  • Children younger than 5, but especially children younger than 2 years old
  • Adults 65 years and older
  • Pregnant women
  • People with the following medical conditions:
    • Asthma
    • Neurological and neurodevelopmental conditions
    • Chronic lung disease3 to 8 years old (vaccinated with influenza vaccine in a previous season)  – One or two doses (0.5 ml each)
    • Heart disease
    • Blood disorders
    • Endocrine disorders (such as diabetes mellitus)
    • Kidney disorders
    • Liver disorders
    • Metabolic disorders
    • Weakened immune system due to disease or medication
    • People who are morbidly obese


Pneumonia is more likely to cause complications in older people, smokers and people with heart failure or lung disease, such as COPD. Pneumonia complications may include:

  • Bacteria in your bloodstream. In pneumonia, alveoli contain bacteria that may enter the bloodstream during gas exchange. Infection then spreads through the bloodstream, potentially causing shock and failure of multiple organs.
  • Septic shock. Unchecked bacterial growth in the bloodstream can shut down normal circulation, cause uncontrolled tissue swelling and possibly organ failure, which can lead to death.
  • Fluid accumulation and infection around your lungs. When the pleurae around your lungs become inflamed as a result of pneumonia, fluid can accumulate and may become infected (emphysema).
  • Lung abscess.
  • Acute respiratory distress syndrome (ARDS). Underlying lung disease of any kind, especially COPD, makes you more susceptible to ARDS.


  • The most effective way to prevent the disease or severe outcomes from the illness is vaccination.
  • Among healthy adults, influenza vaccine can prevent 70% to 90% of influenza-specific illness. Among the elderly, the vaccine reduces severe illnesses and complications by up to 60%, and deaths by 80%.

Vaccines available to prevent Influenza:

Influenza Vaccines

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