Communicable Diseases

Seasonal Influenza


  • Seasonal Influenza is an acute viral infection that spreads easily and affects all age groups.
  • It is transmitted by inhaling droplets containing the virus or touching contaminated surfaces.
  • The incubation period lasts for an average of 2 to 4 days.
  • Taking the Seasonal Influenza vaccine every year is one of the most effective methods of prevention.
  • The majority of individuals who get influenza recover on their own without treatment. 

What is Seasonal Influenza?
Seasonal influenza is an acute viral infection that is easily spread and affects the respiratory system. The flu is caught through the nose or mouth then reaches the lungs. It can range from mild to severe and affects all age groups.
Other names: Flu, Grippe
Types of Seasonal Influenza Viruses:
There are 4 main types of Seasonal Influenza. Some of them affect humans and others affect animals. They are:
  • ​Influenza (A) viruses and influenza (B) viruses: They infect humans and are the cause of seasonal influenza which spreads in winter.
  • Influenza C virus: It infects humans and causes the circulation of flu throughout the entire year. 
  • Influenza D viruses: They affect cattle and are not known to infect or cause illness in people.
There are subtypes of the influenza A viruses, according to the proteins enfolding the virus (H or N). There are 18 different of H proteins and 11 of the N proteins. 

Transmission of influenza A and B viruses to the body. 
  • Inhalation of droplets in the air of an infected person sneezing or coughing.
  • Touching surfaces contaminated with the virus, then touching the eyes, mouth, or nose.

Incubation Period:
An average of 2-4 days.
Infection Duration:
It starts one day before the onset of symptoms up to 5-7 days after their appearance. This period can last longer for children and people who are immunocompromised.
  • Fever (body temperature is 38°C or higher);
  • Chills and sweating;
  • Headache;
  • Continuous dry cough;
  • Fatigue and exhaustion;
  • Runny nose;
  • Sore throat; 
  • Muscle pain.
Some people may not experience fever. 

Risk Factors:
  • Age
  • Chronic diseases
  • Immunodeficiency
  • Obesity

Who is at risk?
  • Healthcare workers
  • People with chronic diseases
  • Children
  • The elderly
  • Pregnant women

When to see a doctor?
Most people with influenza will only need to rest at home. If the disease becomes more severe and lasts for more than two weeks, it is best to see a doctor. Taking medicines within the first 48 hours helps prevent more serious problems.
  • Inflammation of the lungs;
  • Bronchitis;
  • Ear inflammation;
  • Asthma;
  • Heart problems;
  • Blood poisoning;
  • Death.

  • Clinical examination
  • Medical history
  • Laboratory tests

  • Take the Seasonal Influenza​ vaccine every year.
  • Regularly wash your hands with water and soap.
  • Avoid touching your eyes and nose directly after touching surfaces.
  • Avoid direct contact with people who have the flu and refrain from using their personal tools.
  • Use a tissue when sneezing or coughing and dispose of it immediately. 
  • Make sure surfaces are kept clean, such as: Tables and seats.
  • Avoid crowded places. 

It usually involves getting enough rest and drinking plenty of fluids, but in some cases, the doctor may prescribe antiviral drugs.

Why do people get the flu when they take its vaccine?
The flu vaccination does not cause a flu infection. This is due to the fact that the type of vaccine used in the Kingdom is inactivated not attenuated, which means it does not affect humans. There may be two explanations for those who become ill after taking the vaccine:
  • Like any other vaccine, the flu vaccine has side effects, such as: A slight fever, headache, and fatigue. This may cause the vaccinated person to think he caught the flu. 
  • The person may have caught other types of the flu virus, because the vaccine covers only the three most prevalent types of influenza in the Kingdom.
Are some people advised not to take the flu vaccine?
Yes, in some cases, people should not take the vaccine before seeing their doctor. These cases include: 
  • A person previously showing an allergic reaction to the vaccine.
  • A person being allergic to eggs.
  • Infants who are 6 months old or younger.
  • People with high or moderate fever (they can take the vaccine after the temperature has stabilized).​

Myths & Truths:
  • Myth: Antibiotics can kill the flu virus.
    • Truth: Antibiotics work against bacteria not viruses.
  • Myth: Pregnant women should not take the flu vaccine. 
    • Truth: Pregnant women should take the vaccine, as it immunizes them and their fetuses against the flu for up to six months.
  • Myth: Taking the vaccine every year impairs immunity.
    • Truth: Taking the flu vaccine on a yearly basis increases the body’s immunity against the virus. The vaccine would not be recommended by doctors if it had a negative impact on the immunity. 
  • Myth: The flu vaccine causes autism in children.
    • Truth: This is not true and has not been mentioned in any scientific reference.
Clinical Education General Department
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Last Update : 12 January 2023 11:00 AM
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