Vaccination is crucial to protect ourselves and other members of the community against dangerous diseases. Vaccines are safe and FDA-approved, each undergoing a thorough testing and approval process before being distributed to eligible people. Even so, they can cause side effects just like other medicines. Fatigue is one of the most commonly experienced vaccine side effects. But why do vaccines make you tired?
Most of the time, this symptom is very mild and goes away on its own. Let’s explore!
Why People Experience Vaccine Side Effects
Vaccines work by introducing small amounts of weakened viruses into our bloodstream. This triggers the immune system to produce antibodies to fight off germs and defend us from future infections. Immune responses may cause some side effects, a normal reaction experienced by many people.
The immune system is composed of two parts: the innate and the adaptive immune system. The innate immune system, consisting of the human body’s inner and outer surfaces, responds as soon as it detects the presence of pathogens.
As a result, blood flow increases to allow immune system cells to circulate more, prompting redness, swelling, and inflammation. Inflammation causes fatigue, soreness, fever, and other side effects. It may also raise the body temperature to stop the virus from spreading.
As you experience these symptoms, the adaptive immune system functions to produce antibodies and help us achieve long-term protection. Vaccine responses for every individual vary, depending on their gender, weight, age, and health status. Some don’t experience side effects at all, while others go through mild to moderate symptoms.
For instance, many people experience fatigue after receiving the COVID-19 vaccine. It can occur with either dose but is usually reported after the second one. The first shot revs up the body, so it can react instantly after the second dose. This happens even if you don’t experience any post-vaccine symptoms.
Few severe side effects and adverse events have been observed from the billions of vaccines administered worldwide. Most of these symptoms are mild, typically lasting between 24 and 48 hours. These are just signs that the body is starting to build immunity.
Schedule your vaccination only when you have time to rest. Then, get enough sleep and avoid engaging in strenuous physical activities afterward.
Common Vaccine Side Effects
All types of vaccines may cause mild to rare side effects. Aside from fatigue, here are some of the most common mild side effects associated with many vaccines.
- Pain or redness at the injection site
- Fever
- Headache
- Muscle and joint pains
- Diarrhea
- Loss of appetite
While most symptoms are mild, people can still develop severe reactions such as high fever and seizures. Some infants and young children develop febrile seizures and convulsions caused by fever following vaccination. However, this is incredibly rare, and most recover without long-lasting effects.
Moreover, rare severe allergic reactions, or anaphylaxis, may occur, with only one case in one million doses administered. (Yes, it’s literally a one-in-a-million chance!) Symptoms may include swelling of the lips, difficulty breathing, and hives. A pre-vaccination screening questionnaire is used to prevent anaphylactic reactions.
Should it occur, qualified healthcare personnel can recognize anaphylaxis symptoms and provide immediate treatment. This is why it’s crucial to stay in the vaccination state for 15 minutes after receiving the shot. Do note, however, that vaccines are not the leading cause of anaphylaxis. The most common causes are insect bites, antibiotics, food, and medications.
The COVID-19 vaccine specifically may result in rashes, swelling of lymph glands, sleeplessness, excessive sweating, and decreased appetite. Meanwhile, rare symptoms like swelling of the face and hives due to allergic reactions affect only one in 1,000 individuals.
There are reports of myocarditis and pericarditis, both inflammatory heart diseases, following mRNA COVID-19 vaccination. These rare side effects are seen only in obe in 10,000 cases. Blood clots, another extremely rare side effect, have been observed in a small percentage of people, mostly younger individuals.
Difference Between Adverse Events and Side Effects
A side effect is an expected, secondary effect of a vaccine or medicine. These symptoms are documented, observed, and studied during clinical trials. Thus, patients know they may happen after the vaccine is administered.
On the other hand, adverse events are dangerous, unpredictable, and unforeseen conditions that typically lead to medical intervention. They are rarer than side effects and can be life-threatening.
Symptoms can either be a genuine reaction to the vaccine or just coincidental. In other words, these reactions may or may not be related to the vaccine and could have occurred even if they weren’t immunized.
These health issues must be reported as adverse events following vaccination, even though their cause is unknown. In the end, though, there might not be enough evidence to prove that the vaccine caused them.
Vaccines are Safe!
In the U.S., post-vaccination symptoms are submitted to the Vaccine Adverse Event Reporting System (VAERS), a safety reporting system. Together with the CDC, they collect and analyze negative health outcomes following immunization.
Vaccinations are carefully investigated and not automatically regarded as the cause of severe side effects. If there is, indeed, a safety problem, the agencies will get in touch with vaccine manufacturers to solve the issues.
Despite causing fatigue and other side effects, vaccines are safe and effective. They undergo meticulous testing to ensure safety and efficacy and are subject to ongoing surveillance and monitoring efforts. If you experience any adverse event after leaving the vaccination site or days after getting the shot, seek medical care right away.
Fatigue After Vaccination is Normal
Tiredness after vaccination can cause distractions and discomfort, but there’s nothing to worry about most of the time! However, if you experience fatigue and weakness for more than two days, reach out to a healthcare professional to ensure everything’s fine.
