Everything You Should Know About The Flu Vaccine

Since the flu season is upon us, it’s important to get your flu vaccine on time to avoid the viral illness and its spread to people around you. Each year, the flu affects millions of people in the country and leads to several hospitalizations. Considering the ongoing COVID-19 pandemic, it’s all the more important to get your flu shot. In the 2019-2020 season alone, the CDC estimated over 35 million cases of flu nationally, and the caseload led to nearly 20,000 flu-related deaths. 

But how does the flu vaccine work? And how long does it take for the flu vaccine to work? These are common questions in the minds of many, and it’s important that we understand the importance of the flu vaccine to help us stymie the spread of the disease this season. In this article, we unravel the essentials of the flu vaccine and address several concerns to help you remain in better health during this flu season.

What Is The Flu?

  • Seasonal flu, also known as influenza, is a viral disease that attacks the respiratory tract and the lungs. 
  • The condition is caused by two types of influenza viruses - influenza A & influenza B. 
  • The viral disease results in symptoms like fever, cough, headache, body ache, sore throat, runny nose, and malaise. 
  • In most cases, the flu isn’t very severe and the infected often recover within a week. 
  • However, people that are vulnerable and have weakened immune systems are at a higher risk of developing serious symptoms. These symptoms, if ignored, can even lead to death. 
  • The seasonal flu occurs from October to March in the United States. However, cases are reported year-round due to the prevalence of different strains. 
  • So how does the flu vaccine work? Understanding this can help people prevent this condition, and limit the spread of this seasonal epidemic. 

how does the flu vaccine work in the body

How is The Flu Vaccine Made?

  • To understand the nuances of questions like ‘how does the flu vaccine work?’, it's important to know how the vaccine is made. 
  • Before the start of flu season, scientists conduct detailed research and run several predictive models to figure out the prevalent strains of the virus in an upcoming season. 
  • They then synthesize the strains of these viruses artificially in chicken eggs and incubate them. These synthetic strains of the influenza virus are incapable of reproducing independently. 
  • Another method of creating flu vaccines is by using live influenza viruses, but by weakening them using a process called attenuation. This reduces the virulence of the virus and enables your body to overcome it easily.  
  • However, most people are given synthetic shots, as live attenuated vaccines are not suited to individuals with a compromised immune system - young infants, the elderly, and people with debilitating diseases.

Types of Flu Vaccines

There is a range of flu vaccines that help the body defend against a variety of flu virus strains. Understanding the various types will help us understand how the flu vaccines work in the body and what they contain: 

  • Quadrivalent vaccines: These flu shots protect against two strains of the influenza A and influenza B viruses each. A variety of quadrivalent vaccines include recombinant, synthetic, cell-based, and live-attenuated options. These vaccines protect against four strains of influenza viruses in total.
  • Trivalent vaccines: Trivalent flu shots protect against two strains of influenza A and one strain of influenza B virus. 
  • Nasal Vaccines: These vaccines are administered by an aerosol through the nose, and are based on quadrivalent vaccine techniques. The nasal vaccines have a live attenuated viral strain and cannot be given to people with weak immune systems.   

how long is flu shot effective

How Does the Flu Vaccine Work?

The flu vaccine, like several other vaccines, works based on the concepts of acquired immunity. How does the flu vaccine work in the body? Here’s what you need to know:: 

  • The vaccine contains either a synthetic, dead, or live weakened flu virus that triggers an immune response.
  • Naturally, the initial immune response to a virus or any other pathogen is weak due to the body’s limited knowledge of the nature of what it is up against. 
  • The weakened or dead viruses in the vaccine trigger a weak immune response in the body, which helps the immune system create an immune memory to combat future attacks from the same virus. 
  • Following the realization of the complete effects of the vaccine, the body will mount a more aggressive immune response against the actual influenza viruses whenever you encounter them. 
  • This is known as a secondary immune response and forms the backbone of acquired immunity. It is the primary reason why vaccines work. 

How Long Does it Take for the Flu Vaccine to Work?

  • The flu vaccine takes about 2 weeks to protect against the disease. 
  • The antibodies against the flu develop about 14 days after the shot. 
  • It’s important to remember that everyone remains vulnerable to the disease after the shot until antibodies are generated.
  • It is still possible to contract the flu within the two-week period. Coupling the vaccine with basic personal hygiene practices will enable you to avoid catching the flu. 
  • Undertake precautionary measures such as ensuring you wash your hands regularly, avoid touching your nose and mouth, and try to use a hand sanitizer whenever possible. 
  • Although the flu vaccine takes time to take full effect, the vaccine succeeds in preventing several flu cases each year, and in people that do contract the flu despite taking the vaccine, the shot has been shown to reduce the severity of the condition. 
  • Undertaking these precautions along with the flu shot also enables you to stay safe from another prevalent condition - COVID-19, a disease that has a history of making people vulnerable to other respiratory infections. 

 how often should you get a flu shot

For How Long is the Flu Shot Effective?

  • The immunity gained from the flu vaccine is limited and its effectiveness diminishes over time. 
  • The same can also be said for flu infections; something to keep in mind while getting vaccinated against the flu every year. 
  • Flu vaccines are made available in August, however, taking the vaccine too early may render your body vulnerable to the infection during the later months of the season. 
  • Early vaccinations are recommended to vulnerable groups such as young infants, seniors, medically compromised, and the disabled. 
  • The right time to take the vaccine is during the end of October, or early November so that the immunity gained from the vaccine lasts throughout the season, and helps you remain safe. 
  • How often should you get a flu shot? The answer’s typically once every year. However, certain age groups like young children are advised to take a booster shot about four weeks after the first shot. 
  • The flu shot’s protection ideally lasts about 6 months and can help you avoid the infection throughout the season if taken on time. 
  • However, if you’re late for the vaccination, there’s no reason to worry. Several hospitals and primary care centers offer the flu vaccine through March and can help you stay safe from the infection. 

Who Should Get the Flu Vaccine?

Everyone above the age of 6 months is advised to get the flu shot every year. This is especially important for vulnerable populations. People that have experienced adverse reactions to the vaccine, or are allergic to it, must contact their doctors and care providers to figure out alternatives to traditional flu shots. 

 how long does it take for the flu vaccine to work

Common Side Effects of the Flu Vaccine

To understand how the flu shot works, it’s also important to remain aware of the common side effects that are encountered following the vaccination. The symptoms include: 

  • Pain at the injection site
  • Swelling and redness at the injection site
  • Low-grade fever
  • Body aches 
  • Fatigue 

Side-effects are common following the injection and last for about two to three days. It is important to report to the doctor if you experience symptoms of allergies or a hypersensitivity reaction to the vaccine. 

The influenza virus poses a greater challenge during the ongoing COVID-19 pandemic, owing to its tendency to affect vulnerable populations. It is all the more important to get vaccinated against the flu so that you can lead a safe and healthy life during these colder months. Contact your doctor or nearest primary care center to learn more about the flu vaccine.