What is the Flu Shot? Definition

The flu shot also referred to as the influenza vaccine, is an injection or a nasal spray that you take every year to protect yourself from getting the seasonal flu.

It protects you against the four influenza viruses that research indicates will be most common during the approaching season.

Besides the dead or attenuated flu viruses, it also has certain ingredients that increase its efficiency.

Why take the flu shot every year? Benefits

There are compelling reasons for taking the flu vaccine every year. Taking the flu shot annually prevents you from catching this viral illness by as much as 60%. This becomes more important especially when you are a high-risk candidate.

In addition, from the statistics of mortality more so during the flu epidemics and pandemics, when you see the misery caused and the deaths of thousands of people, you will want to protect yourself with the vaccine.

There are three types of flu viruses: Influenza A virus, influenza B virus, and influenza C virus. All these types of viruses mutate or change their form or properties making the vaccine used during the previous year, ineffective against them.

It becomes necessary, therefore, to manufacture a new vaccine every year, which is effective against the prevalent strain. This evolving nature of the virus makes it necessary to take the newly modified vaccine every other year.

It significantly reduces your chances of catching the flu by 60% and in those who are unfortunate to catch the flu, it prevents complications from setting in.

In children, the dangers of this illness can be serious.

In spite of repeated recommendations, only half the Americans take the flu vaccine.

How does the flu shot vaccine work?

When the vaccine containing the dead or weakened viruses is administered, the body treats the weakened viruses as foreign bodies and starts to produce antibodies to fight the viruses.

It takes about two weeks for our body to make the antibodies that can ward off an attack of the virus strains that are present in the vaccine.

The vaccinated person, with the antibodies already present in his body, is now better equipped to fight off the viruses that populate the air during the flu season.

Flu shot administration: Methods

There are different types of vaccines and they all have a different recommended method of administration and site. This information is included in the literature in the packet of the vaccine. Any change in the recommended route may reduce vaccine efficacy or it can increase local adverse reactions.

You can take the flu shot vaccine by intramuscular or intradermal routes. You can even take the vaccine through the nose by means of a nasal spray (flu mist vaccine). The nasal spray vaccine contains live but weakened or inactivated viruses.

Cost of the flu shot

The flu shot is not free, nor is it subsidized. It will cost you on average, about $30 in the United States. However, the high-dose flu vaccine will cost $55. The cost varies depending on where you take the flu shot and whether you have medical insurance.

In India, the price of the influenza vaccine ranges from around ₹800 to ₹1,500 per shot.

Why is the flu vaccine more expensive?

This expensive figure for the flu shot is due to the fact that every year in February, a new vaccine has to be developed and the vaccine of the previous year has to be discarded because it becomes ineffective against the new strain of the virus.

The subtypes of these viruses keep on mutating every year because of resistance developed by the virus to the vaccine of the previous year and sometimes these mutations result in viruses that move from animals to humans.

After research has established the most likely strain, manufacturing is taken up and an estimate of the doses required during the year is calculated from pure guesswork.

At times, there is too much wastage if the influenza season is mild and most people opt not to get vaccinated. On the other hand, manufacturing lesser quantities will result in shortages for which the media will tear down the authorities.

Vaccines for other illnesses, such as measles and mumps can be used till the expiry date. This is usually years after the manufacturing date. Not so for the flu vaccine, which is used only for one year due to the reason explained above.

Can the flu shot make you sick?

The standard influenza shot by itself, cannot make you sick but it reduces your chances of catching the flu by 60%.

The nasal spray vaccine contains live attenuated (weakened) viruses and may cause mild symptoms in some people, especially those with accompanying high-risk factors and a compromised immune system.

Again, there are reasons that can make you ineligible to take the vaccine. For example, the doctor will not recommend the shot if you are sick or have a fever. Once you recover, you can take the vaccine.

How is the flu shot researched and manufactured every year?

The most likely influenza virus strain is researched by health officials by visiting Asia in January or February every year and finding out which strain is active there.

Most of the viruses originate and mutate in Asia and Africa where closeness between humans and livestock is more proximate.

The prevalent strain of the virus in the southern hemisphere is also found during its winter to determine the most likely strain to hit the northern hemisphere in the coming fall.

This is due to the stats that tell you that these strains will most likely attack the United States in the fall. A new vaccine is then produced for these new strains. The old vaccines lose their effectiveness and do not offer any protection against the new strains.

Is the flu shot effective and for how long? Influencing factors

How effective the influenza vaccine is, will depend on:

  • the age of the person,
  • his quantum of exposure to the risk factors and
  • whether the virus strain in the vaccine matches the strain in circulation.

The seasonal flu vaccine is effective only against the strains of the virus for which it is matched. It is effective against the three influenza viruses, which research renders to be the most likely strain of the viruses to be active during the coming season.

The three types of viruses are:

  1. H3N2,
  2. the influenza type B virus,
  3. and the H1N1 virus, which was responsible for the pandemic of 2009.

After taking the vaccine, antibodies to the virus develop and their levels peak after two to four weeks. They fall by 50% over the next six months and then remain stable over the next two to three years.

The vaccine does offer protection for a 12-month period, especially to children and young adults, but only against the strain of the virus, the vaccine is matched for.

And, since the virus keeps on mutating into new strains every year, it is necessary that you take the flu shot vaccine every year to protect yourself against the new strain of the virus.

That is why the CDC recommends that ideally, you should take the flu shot just before the start of the flu season, which is the season of the dark, cold, winter months.

At what age can you take the flu shot?

The flu shot is recommended for all above the age of six months. For people above the age of 65 years, the shot is recommended twice during the influenza season. The reason for this is that the immune system weakens due to aging.

Where to get the flu shot?

The influenza vaccine is available at a number of places:

  • You could ask your doctor
  • Retail drug outlets
  • Local health centers
  • Vaccination clinics
  • Some schools and workplaces also offer vaccination facilities.
  • Local Government health services have their websites, which give addresses of the places where you can take the vaccine.

When to take the flu shot? Best time

CDC recommends that you should take the flu vaccine as soon as it becomes available, which, in the United States is in the month of September just before the start of the flu season. Though the level of antibodies to the vaccine declines over the months, they still remain high enough to provide protection for the full length of the season.

In other areas too, people should take the vaccine just before the onset of the cold winter months keeping in mind that the antibody titer takes 2 to 4 weeks to peak. Remember, the season of this viral infection is the time of cold dry winter months and therefore. differs in the northern and southern hemispheres.

In the United States, the flu season starts in October and lasts up to May with its peak in February. It can, however, peak as early as October or sometimes as late May.

In the United Kingdom, the season starts in October and ends in April.

In Australia, which is in the southern hemisphere, the flu season is from May to October with its peak in August.

Flu shot side effects and dangers

Serious problems and mortality due to the flu vaccine are very rare, almost non-existent.

You may experience some mild side effects such as:

  • A bruise at the injection site showing soreness, redness, and swelling
  • Shoulder and arm may pain
  • Low-grade fever

These side effects do not last beyond one to two days.

Serious allergic reactions to the flu vaccine are rare, but they may occur in people who are allergic to certain contents in the vaccine.

Such ingredients that can cause allergy are chickens or eggs, mercury, certain antibiotics, and gelatin.

Signs of allergic reaction to the vaccine include:

  • Breathing difficulty
  • Wheezing
  • Skin reactions such as hives
  • Rapid heartbeat
  • Dizziness

Is the flu shot safe during pregnancy?

During pregnancy, the woman’s immunity is weakened due to changes in the body because of the developing fetus. The flu virus can overcome the immune system and multiply without any serious opposition.

Therefore, their illness can become very severe in intensity and may lead to hospitalization and even death of the pregnant woman.

As a result, it becomes essential for pregnant women to take the influenza vaccine. It protects the woman and the baby for the first six months after birth.

However, there are certain riders attached to giving the vaccine to the pregnant woman.

Firstly, the vaccine used should be one that contains dead viruses. The nasal vaccine, which contains live inactivated viruses is, therefore, contraindicated in pregnancy.

Secondly, if the woman is allergic to any components of the vaccine such as egg protein, she should not take the shot for fear of her developing a severe allergic reaction.

However, barring these cautionary measures, pregnant women can take the vaccine during any trimester of the pregnancy.

Flu vaccine recommendations before a surgery

You can have the flu vaccine before surgery but there are some recommendations to follow. There are some differences of opinion between surgeons, but it all boils down to this:

1.     If you are taking the standard shot, take it at least one week before surgery

2.     If you are taking the nasal spray vaccine, you should have it at least two weeks before the surgery.

Ideally, the medics prefer the standard version of the vaccine before the surgery. This is because the live version (nasal spray) contains live viruses that can cause you to suffer from mild flu symptoms.

This can cause other nearby patients and visitors to become susceptible.


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