Influenza is a virus that infects millions of people across the globe every year. For some, it may be a mild or moderate illness, while for others, it can prove fatal. Influenza is spread through the saliva and respiratory droplets of an infected individual. It can be transmitted through coming in contact with a contaminated surface, sharing utensils with an infected individual, when respiratory droplets spread from coughing or sneezing, and any other event or action that exposes you to infected materials.
The seasonal influenza vaccine is used to decrease the chances of contracting influenza if exposed to the virus. Some might ask, I got the flu vaccine. Why am I sick? There are a few reasons that this might occur. Let's dive in and learn more about influenza and why you might feel sick after getting the vaccine.
Immune Response
One of the most important aspects of vaccine education is learning about the body's immune response after receiving a vaccine. When a vaccine is administered, the body begins to recognize and respond to the vaccine and the illness it is designed to prevent.
Some individuals may have no reaction at all, while others may find themselves experiencing symptoms or potential discomfort afterwards. This varies depending on the individual, their potential previous exposure to the illness, and other preexisting medical conditions.
An immune response to a vaccine is an indicator that your body is learning to defend itself against the virus. Signs of an immune response from a vaccine may include both localized (at the injection site) and systemic (whole body) reactions such as:
- Pain at the injection site
- Redness at the injection site
- Swelling at the injection site
- Fatigue
- Muscle aches
- Chills
- Fever
- Joint pain
- Lymph node swelling in the extremity
There may also be reactions with the nasal spray version of the vaccine, including congestion, a runny nose, cough, and headache.
These symptoms are most often present within the first 24-48 hours after vaccine administration, but may be present for a few days. It is important to recognize that an immune response does not mean you are infected and have contracted influenza, but is instead your body's way of learning to fight off the real infection, should you encounter it.
It is also pertinent to address and be aware of the signs of an allergic reaction to a vaccine. While an allergy to a vaccine may be rare, it is still possible to have a reaction to a component of a vaccine. Immediate medical attention should be sought if someone exhibits signs of an allergic reaction, which may include, but are not limited to:
- Hives
- Itching
- Swelling of the mouth, throat, lips, or tongue
Any concerns regarding an immune reaction or potential reaction to a vaccine should be addressed with a healthcare professional.
A Mutating Virus with Different Strains
The influenza vaccine is an effective way to prevent yourself from contracting influenza, but it is not always completely effective. Understanding how the influenza vaccine is made can shed light on why you may still contract the flu, even after getting your flu vaccine this year.
Influenza is a mutating virus, meaning it is constantly adapting and changing. This is why it is recommended that people receive a new vaccine each year. There are also multiple strains of influenza that are spread across the globe.
The influenza vaccine is adjusted each year to try to aim its protection against the most prevalent strains, and the strains that are most likely to become aggressive within the upcoming flu season. For those who are at higher risk for contracting influenza, or who are at higher risk for severe illness, such as infants, older adults, or those with certain preexisting medical conditions, a healthcare provider may recommend what is called a high-dose flu vaccine.
These vaccines, as the name would suggest, are a higher dosage and are designed to provide additional protection to those who may require it. So, while the influenza vaccine is effective, it is not perfect, and there is still a chance of contracting a strain of influenza that you were not vaccinated against.
Differentiating Illnesses
It is important to recognize that there are many illnesses that can produce some of the same symptoms as influenza. COVID-19, norovirus, and respiratory syncytial virus (RSV) are a few of the viruses that may cause symptoms similar to those caused by influenza. Common symptoms of influenza include:
- Fever
- Chills
- Muscle aches
- Joint pain
- Nausea
- Vomiting
- Diarrhea
- Fatigue
- Loss of appetite
The best way to confirm what virus you may have contracted is to be tested through a nasal swab at a healthcare provider's office, an urgent care center, or an emergency room. If you do have influenza, an influenza test can also help determine which strain you are infected with. Medical attention should always be sought if there are any potential concerns, if symptoms appear to be life-threatening, or if your condition is worsening or not improving.
Conclusion
Becoming educated about influenza, how it spreads, and what symptoms you may experience, as well as learning about the influenza vaccine and how it functions, can help you make an informed decision as to whether to receive it each year.
Understanding the body's immune response to a vaccine, what other illnesses have symptoms that can potentially mimic the flu, as well as the process of strain selection for the vaccine, can help dispel confusion and provide answers to questions surrounding why individuals experience symptoms or feel unwell even after receiving the influenza vaccine.
About the Author:
Rachel Pugmire is a registered nurse and freelance writer. She received her Bachelor of Science in Nursing in 2018, with a minor in gerontology. Her areas of expertise include emergency medicine, pediatrics, and pharmaceutical clinical trials. Medical writing has given her a platform to do what she is passionate about, which is educating patients, their families, and other healthcare professionals.
Rachel is an independent contributor to CEUfast's Nursing Blog Program. Please note that the views, thoughts, and opinions expressed in this blog post are solely those of the independent contributor and do not necessarily represent those of CEUfast. This blog post is not medical advice. Always consult with your personal healthcare provider for any health-related questions or concerns.
If you want to learn more about CEUfast's Nursing Blog Program or would like to submit a blog post for consideration, please visit https://ceufast.com/blog/submissions.
