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What is the flu?

Flu is a contagious respiratory disease caused by viruses that infect the nose, throat, and lungs. Flu symptoms can be unpleasant, but if you have a healthy immune system, you will usually get well in about a week. However, the flu can cause serious complications, especially in young children, the elderly, and those with certain medical conditions. Anyone in these risk groups is likely to develop serious flu complications, such as pneumonia (a lung infection), so it is recommended that you get the flu vaccine every year for protection.

How does the flu vaccine work?

Within two weeks of administration, the flu vaccine causes protective antibodies against flu viruses in its composition.

The seasonal flu vaccine protects against the flu viruses that research indicates will be most common next season. Most flu vaccines protect against three strains of the flu virus (“trivalent”): one strain of flu A virus (H1N1), one strain of flu A virus (H3N2) and one strain of flu B virus, and four strains of the flu virus (″quadrivalent″): one strain of flu A virus (H1N1), one strain of flu A virus (H3N2) and two strains of flu B virus.

The vaccine is only effective against flu virus strains involved in the epidemic, so annual vaccination is required.

Types of flu vaccine

Every year, the composition of flu viruses changes, which makes the vaccine used in previous years ineffective. Every year, a new vaccine must be prepared that is effective against flu virus strains that are expected to circulate in the next flu season. It is known as the ″seasonal flu vaccine″. The flu virus can quickly mutate, leading to new subtypes of the virus. Usually, the viruses used to prepare the flu vaccine are grown in eggs.

There are two types of flu vaccine:

1. Flu shot vaccine: This type of vaccine can be given to all age groups from 6 months of age. The flu shot vaccine contains an inactivated virus. None of the components of the vaccine can cause the flu. A single dose of the vaccine is given by injection into a muscle or deep under the skin. Two types of flu vaccine are available: a trivalent vaccine targeting three strains of the flu virus and a quadrivalent vaccine targeting four strains of the flu virus.

2. Nasal spray flu vaccine: This type of vaccine is given to children aged 2 to 17 years. The nasal spray flu vaccine contains live attenuated virus. In recent years, there has been concern that the nasal spray flu vaccine has not been effective enough against certain types of flu. This vaccine is expected to be more effective in the 2020-2021 season. Doctors recommend that all children over 6 months of age be given the flu shot vaccine if possible because it has been shown to be more effective against all strains of the flu virus.

Who should get the flu vaccine?

It is recommended that anyone over 6 months of age get the flu vaccine, especially those at high risk of developing serious complications:

  • Pregnant women
  • Adults over 65 years
  • Young children
  • Asthma
  • Cancer or cancer treatment
  • Chronic obstructive pulmonary disease (COPD)
  • Cystic fibrosis
  • Diabetes
  • HIV/AIDS
  • Kidney or liver problems
  • Obesity

Anyone with a chronic condition should get the flu vaccine.

Who should not get the flu vaccine?

Consult your doctor before getting the flu vaccine if:

  • You are allergic to eggs: The flu vaccine contains a small amount of egg protein. If you have a mild egg allergy, you can get the flu vaccine without any additional precautions. If you have a severe egg allergy, you may need to be supervised by a doctor who is able to recognize and manage severe allergic reactions.
  • You have had a severe reaction to a previous flu vaccine: The flu vaccine is not recommended for anyone who has had a severe reaction to a previous flu vaccine.
  • You have Guillain-Barré syndrome (an inflammatory peripheral neuropathy) that has occurred after the flu vaccine.
  • If you have a fever when you go for the flu vaccine, you should talk to your doctor if you need to delay it.

How effective is the flu vaccine?

The flu vaccine is generally more effective among people under the age of 65, but the level of protection may vary, so there is no 100% guarantee that you will not get the flu. Even if the vaccine does not completely prevent the flu, it can reduce its severity and reduce the risk of serious complications that require hospitalization.

Some seniors and people with certain medical conditions may develop lower immunity after getting the flu vaccine. Analysis of previous studies has found that the flu vaccine is 50% to 60% effective for healthy adults between the ages of 18 and 64. If you get the flu after you have been vaccinated, it is likely to be a milder and shorter form.

The flu vaccine does not protect you against the COVID-19 virus. However, it is very important to get your flu vaccine this season because the flu and COVID-19 cause similar symptoms. Flu vaccination may reduce symptoms that may be confused with those caused by COVID-19. Preventing or reducing the severity of the flu could also reduce the number of people in need of hospitalization.

Side effects of the flu vaccine

Serious side effects of the flu vaccine are very rare. However, there are some mild side effects of the flu shot vaccine, such as pain at the injection site, muscle aches, fever, and feeling sick. Very rarely, people have reported severe allergic reactions. Side effects of the nasal spray flu vaccine may include runny nose, mild fever, sore throat, cough, muscle aches, fatigue, headache, loss of appetite, and vomiting.

Guillain-Barré syndrome is a disease characterized by fever, nerve damage, and muscle weakness. In 1976, the flu A (H1N1) vaccine against swine flu was associated with the development of Guillain-Barré syndrome.

What time of year should the flu vaccine be given?

The best time to get the flu vaccine is in the fall before the flu starts circulating. The flu season can start in October and last until May.

How to reduce the risk of the flu without the flu vaccine?

The flu vaccine is the best method of defense against the flu, but there are additional steps you can take to protect yourself from the flu and other viruses, including COVID-19:

  • Wash your hands often with soap and water for at least 20 seconds.
  • Use an alcohol-based disinfectant if you do not have soap and water on hand.
  • Avoid touching your eyes, nose, or mouth.
  • Avoid crowded places during the flu season.
  • Avoid contact with sick people.
  • Cover your mouth with a napkin when you cough or sneeze or use your elbow, then wash your hands.
  • Regularly clean and disinfect common surfaces to help prevent the spread of infection.
  • Exercise regularly, get enough sleep, drink plenty of fluids, choose a healthy diet, and manage stress.
  • If you get the flu, you can also help prevent the spread of the infection by staying home and avoiding contact with other people.

During the COVID-19 pandemic, both COVID-19 and the flu can spread at the same time. Choose social distance and keep 2 meters distance from other people. Wear a face mask in public transport, shops, and other enclosed spaces.

Taking the flu vaccine can reduce the risk of the flu and its complications and following these measures can help protect you from respiratory illnesses.

If you want to find out the differences between cold and flu, check out our article on this topic: What is the difference between cold and flu?

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