When Should You Get A Flu Shot And How Long Should It Last?

To fight the influenza virus, flu shots are the medicine of choice. Though often neglected by many, this is one severe virus that causes a variety of illnesses that can even lead to deaths every year.

An individual doesn’t have to be young or have a compromised immune system to get the virus and become ill. 

It has been seen that healthy people often get sick from the virus and are the community’s main carriers. As a result of this, the community spread occurs, where death due to influenza-related cases is dominant for individuals over 65 years old. 

The community spread of the flu also puts children younger than five years; people with other medical conditions and pregnant women at increased health risk due to the complications of influenza. 

According to Centres for Disease Control and Prevention (CDC), the best way to avoid getting the virus is vaccinating. The vaccination can be done with an injection or as a nasal spray.

How does the flu vaccine work?

It is not the vaccine that helps us prevent getting sick; rather, our immune system does the work. Rather our immune system gets trained by the vaccine to fight the influenza virus. 

The vaccination works on 12 basic steps; they are:

1. The shots contain a dead or weak virus or the virus’ proteins along with different stabilizers.

2. These viruses put in the serum are called antigens, which help stimulate the immune system. In return, the stimuli prepare the immune system to fight the virus without making the person who received the shot ill. 

3. After receiving the vaccine, the immune system starts working by examining the shot’s antigens. 

4. The next step takes time when the immune system produces the custom tools (the antibodies) that will target the antigens that have been delivered by the shot.

5. During this time, the individual who received the injection can experience tenderness around the area where they received the shot. 

6. During this time one can also experience other side-effects like headache and slight fever. But this won’t last for long as this is the reaction of the general immune system to the invader (antigens) into the body.

7. After the immune system has the right antibodies that can fight the virus, it makes several copies of it, just like it would do when one caches the influenza virus.

8. It takes about two weeks for the body to develop the antibodies fully to combat the virus.

9. During these 14 days, the body can still fight the virus that one can contract from outside with the already created antibodies or some present in the system. 

10. As a result of the shot, the body also has memory cells that can remember the antigens that it got from the shot and the antibodies that fight best with the virus. 

11. Despite the decrease in antibodies over time, the memory cells created to fight the antigens will recognize the virus and develop the antibodies to fight it. 

12. Antibodies can be created quickly by the memory cells as they are always ready to fight the virus. 

However, CDC states that a person should get vaccinated every year. The reason the virus strain changes and researchers develop a vaccine that will combat that strain.

When does the flu vaccine start working?

Typically the influenza vaccine becomes effective after 2 weeks once the individual receives it. The antibodies start developing during these 14 days. After these 14 days, the vaccinations start working fully to give protection from the virus. 

During this time, the individual who received the shot needs to remember that the body is still not protected from the virus; hence there is a chance of getting ill from the virus. One must extra careful to stay safe. Some of the necessary steps one can follow to avoid contracting the virus are:

  • Avoiding crowded place, hence prevent themselves from getting infected from community spreading
  • Avoid touching mouth and nose as much as possible.
  • Maintain good hygiene 

These precautions are extremely vital, while COVID-19 is still an issue. As a result of contracting the bug one can develop other respiratory infections that can be fatal. Hence one must protect themselves and others from getting influenza by getting the shot. 

How long does flu shot last?

Despite getting influenza shot last year are still getting the chills fever, nasal congestion, and flu-like symptoms? You may be coming down with the flu. But since you got the shot last year, how is it possible you are feeling that way? 

This brings to the question of how long does the shot last? 

According to experts, the answer is typically six months. But once again, this can change since every human being’s body, and the constitution is different. 

CDC states that the first three months after getting the vaccination, the person is most protected. However, it can be effective for the next three months. Therefore an individual is covered for six months. 

Therefore, it is important to do the math and get the flu shot at the right time of the year to stay covered and as a preventive against the virus.  

Best time to get vaccinated 

Now that we know how long the shot lasts, it is essential to know when will be the best time to get vaccinated. Generally, the season for the virus to reach its peak is between December and March. People should consider getting the shots before the peak time. Doctors recommend at least two weeks before the season peaks to get the full immunity from the shot. 

Many doctors and health specialists advise that the best time to get vaccinated is between September and October, preferably the end of October. 


Unless advised by the doctor for some other medical reasons, one should get a flu shot every year. Anyone above the age of six months old should get the shot to prevent the infections caused due to the virus from becoming fatal. Though it is not 100% effective, it will make sure you feel less under the weather after getting the shot.