A brief overview of the flu
The flu is caused by influenza viruses A and B. The viral infection, causing a respiratory condition, is very contagious and easily spread through the mucous of an infected person. The common cold and the flu are often confused as being the same thing, however, they are both caused by different viruses. The common rule of thumb in telling the difference between them is that flu symptoms are more severe. Flu is most common in winter months and at the beginning of spring. This is known as flu season and also why the condition is often referred to as “seasonal flu”.
The common symptoms of both flu and the common cold are a runny nose, sneezing, fatigue and body aches. However, the common cold rarely causes any other health issues. The flu, however, may lead to ear and sinus infections, sepsis and even pneumonia.
If any of these symptoms persist, it is best to see your doctor for a diagnosis. If a cold is the diagnosis, then common over-the-counter treatment is advised. These kinds of treatments may also be beneficial for the flu in the early stages.
What is the flu vaccine?
The influenza virus is one not to be taken lightly. Leading to many illnesses every year, it can affect those with weak and even healthy immune systems. Fitness and health often have little to do with your immunity, although being healthy can improve your chances of not getting the flu, you may still be at risk, however. It often spreads through families and social circles. Most people develop the common symptoms of a cough, sore throat, congestion, headache and fatigue, however, in some more severe cases, it can be life-threatening, but this is more common in people over the age of 65 and others with weakened immune systems.
The best way to ensure a higher chance of immunity and avoid the spread of the flu, is to get vaccinated. The flu vaccine is injected and often referred to as the flu shot. It is recommended that everyone from the age of six months and up should get the flu vaccine annually.
How does the flu vaccine work?
Each year the strain of flu is different and new vaccines are developed to keep up with the changes and developments of the seasonal flu at the time. In order to make a vaccine that will allow you to be immune to the strand of flu expected to strike for the specific season, three strains of the flu are selected which are predicted to thrive for that specific period.
Scientists research what the predicted common flu will be for the next flu season. They then produce and distribute millions of the vaccine with the predicted flu strain. The vaccine is made up of the weakened or killed organisms of the flu virus in order to make the recipient immune to the virus.
Trivalent vaccines, which are traditional flu vaccines, are developed to protect you from three strains of the flu; an influenza A (H3N2) virus, an influenza A (H1N1) virus, and an influenza B virus. This is the most commonly used vaccine. However, flu vaccines are also developed to protect you against four different strains of the flu, these are called quadrivalent vaccines, which protect against the same viruses as the trivalent, but also include the B virus as an additional virus.
What happens to my body when I get the flu vaccine?
Once you receive the flu vaccine, which is basically a significantly weakened or counterfeit (fake) version of the expected flu virus for the season, your immune system starts to produce antibodies. These are able to protect you from the virus, making you immune to it should you come into contact with it at a later stage. However, it does not offer you protection against other strains of the flu, but it will lessen your side effects should you fall ill. After being vaccinated it will take your body about two weeks to fully develop the antibodies.
What are the different types of the flu vaccine?
There are two main types of the flu vaccine, being the shot or the nasal spray.
The high-dose flu shot
This has been approved for people aged 65 and older. It is a more effective vaccine, containing four times more antigens than the normal vaccine dose. Antigens are known as components of the flu vaccine which stimulate the immune system response, resulting in the production of antibodies.
This vaccine is proven to be more effective with older people as their immune systems are often weaker, thus giving them a potentially higher level of immunity.
The intradermal flu shot
Known as Fluzone Intradermal, it is used for people that are between the ages of 18 and 65 years old. As opposed to the typical flu vaccine being injected into the muscles of the arm, this vaccine makes use of smaller needles that are 90% smaller than the needle used for the regular flu shot and enter just under the skin.
It works just as well as other vaccines, however, side effects are often more commonly experienced.
The side effects at the site of the injection are:
Other side effects can include:
- Muscle aches
All of the above side effects should pass in about three days to a week.
The nasal spray flu vaccine
This is recommended under the following conditions:
- The recipient is NOT pregnant
- The recipient is between the ages of two and 49 years old
- The recipient does not have any chronic medical conditions
The nasal spray results are nearly the same as the normal flu shot, but not as effective. However, certain people who should not receive the nasal spray vaccine are:
- People who are older than 50 years of age
- Children who are younger than 2 years of age
- Children who have had a wheezing episode in the past year and are between the ages of two and five
- Pregnant women
- People who have experienced a severe reaction to the flu vaccine
- People who have asthma
- Children and teenagers who are on aspirin therapy
- People who have a severe egg allergy, mildly allergic people might still be able to be vaccinated once they have spoken to their doctor
- People with nerve or muscle disorders that might make swallowing difficult
- People who have a history of Guillain-Barré syndrome (GBS)
- People who have a weakened immune system
How do they make the flu vaccine?
There are three different ways to make the flu vaccine. Different manufacturers prefer different technologies, these being:
- The egg-based flu vaccine, which is the most common manufacturing process, has been used for over 70 years. It is used to make the inactivated (killed) vaccine, known as the flu shot, as well as the live attenuated (weakened) vaccine, which is normally known as the nasal spray.
The candidate vaccine viruses (CVVs), which are viruses provided by the manufacturer based on the expected flu strain for the season, are injected into fertilised eggs and are incubated for several days to allow for the viruses to replicate inside the egg. The fluid containing the virus is then harvested, inactivated (killed) and purified for the flu shot.
For the nasal spray version, the virus is weakened and goes through a different process to weaken it.
- The cell-based flu vaccine, which until recently, also began with egg-grown CVVs. The process of creating the cell-based vaccines begins when the CVVs are inoculated into cultured mammalian cells, instead of using hen’s eggs. They then replicate over several days and the fluid containing the virus is harvested from the cells. The virus antigen, after being collected, is then purified.
- The recombinant flu vaccine, which uses recombinant technology (the process of recombining material or organisms), and does not involve chicken eggs. The process instead involves isolating a protein that has naturally occurred (known as a wild type) from a recommended vaccine virus for the upcoming flu season. This protein is the HA protein which creates an immune response in people. The protein is then combined with pieces of other viruses that grow well in the cells of insects. This recombinant vaccine is then combined with the cells of insects in order for it to replicate. The virus is then harvested and purified. It is currently the only 100% egg-free vaccine available.
Who should get the flu vaccine?
It is recommended by doctors and healthcare professionals that everyone over the age of six months receives the flu vaccine once a year. People who are of a higher risk of contracting the flu are advised to get the vaccination. These people are:
- Those over the age of 65
- Children who are younger than five years old
- People who suffer from chronic illnesses that have weakened their immune system
- Pregnant women
It is recommended that you get the flu vaccine at least two weeks before flu season, this is due to the fact that the antibodies take two weeks to properly form.
What are the side effects of the flu vaccine?
There are a lot of people who avoid getting the flu vaccine thinking that the vaccine might make them sick. However, the flu vaccine cannot make you sick, while it has some side effects, it cannot cause you to get sick because of the actual vaccine. The weakened or killed strains of the flu virus in the vaccine are not strong enough to make you sick.
Side effects from the vaccine only last a few days and most people do not experience them. If you have experienced any severe allergic reactions to vaccines or medication before, speak to your doctor.
The side effects that are most common include:
- Mild muscle aches and stiffness
- A slight fever
- Soreness and possibly redness around the site of the injection
More serious side effects can include; high fever, dizziness and fainting, severe allergic reactions and in some very rare cases, some people have experienced Guillain-Barré syndrome (GBS), which is a condition that causes weakness and sometimes paralysis through the body. However, it has not been confirmed that the flu virus is the cause of this and it is more likely that people who have suffered from GBS in the past, will develop it again.
If you experience any severe symptoms after receiving the flu vaccine, call you doctor for an assessment.
Some more questions answered
Why do you need to get a flu vaccine every year?
Every year the flu virus is different. New vaccines, therefore, have to be developed in order to keep up with the changes, therefore last year’s vaccine might not be able to protect you from this year’s seasonal flu.
Can I still get the seasonal flu even if I have had the annual flu vaccine?
It is still possible to get the flu if you are vaccinated. Your immunity from the vaccine is dependent on the age and health status of the person being vaccinated. It also depends on how close to vaccine matches the seasonal flu at the time. Your body creates antibodies for the specific strain of the virus that was predicted if you are vaccinated, and the strain you contract is, in fact, different to the suspected flu, you may not be immune to it. The closer the match of the vaccine to the current virus, the higher your immunity.
However, antibodies that are not directly matched to the specific flu strain may still be able to lessen the symptoms of the different flu strain and can sometimes even protect you from it, this is called cross-protection.
Is it safe to get a flu vaccine when pregnant?
It is safe to get the flu vaccine when pregnant and it can be administered during any one of the trimesters of pregnancy. It is recommended to get the vaccine in order to protect the mother and the developing baby from the flu. However, the nasal spray vaccine is not recommended for pregnant women as it is made from a weakened strain of the virus which can be dangerous for the baby and mother.
Can you get the flu from a flu vaccine?
The flu vaccine contains killed or weakened strains of the flu virus. Therefore, due to the virus being inactive, the shot cannot cause you to get sick, it only enables your body to produce antibodies to defend you against a few specific strains of the flu should you come into contact with them.
How long does the flu vaccine protect you?
Your body’s immunity will decline over time. The antibodies start to wane due to your general health and age. It is suspected that the general time of immunity will last about a year.