A common viral infection that attacks the respiratory system. It is usually mild to moderate, but in high-risk groups, it can be fatal. It is also known as ‘the flu’.

Flu vaccines, when available, are effective in preventing influenza virus infection. There are several flu vaccines that prevent different strains of the flu virus.

People who are infected with SARS-COV-2 experience many flu-like symptoms and doctors advise them to get tested as soon as possible. Early in the pandemic many commentators, including political leaders, dismissed COVID-19 as being similar to the flu, saying that it would disappear. In fact, although both diseases have some similar symptoms there are several differences between them, with many COVID-19 patients experiencing far more severe and longer-lasting symptoms.

There can be many causes of flu-like symptoms, including infections like malaria, influenza, COVID-19 and Ebola. Flu-like symptoms include the following:

  • a sudden fever – a temperature of 37.6C (99.68 F) or above
  • aching body
  • feeling tired or exhausted
  • dry cough
  • sore throat
  • headache
  • difficulty sleeping
  • loss of appetite
  • diarrhoea or tummy pain
  • chills

Seasonal flu refers to the annually recurring time period when there are a higher number of influenza cases and outbreaks. It typically aligns with the colder part of the year (autumn, winter, spring) in each hemisphere, and may occur during rainy seasons in some countries. In the northern hemisphere, the flu season is from October/November to April. In the southern hemisphere, that pattern is reversed.


Infectious Disease


High Risk GroupSARS-CoV-2COVID-19FeverDry coughSpanish flu pandemic