Individuals travelling to locations with a high number of yellow fever cases are administered yellow fever vaccine. This helps prevent the recipients from falling sick from the disease, and is typically administered for adults and children above nine months. The vaccine is also administered to professionals in research positions and other responsibilities in laboratories that conduct research about the disease for developing suitable medications and vaccines. Like most vaccines and medications, the possibility of undesirable effects exists, and following subsections offer a detailed look at possible yellow fever vaccine side effects. This helps vaccinated populations to identify and avoid unwanted outcomes.

Overview of the yellow fever vaccine

Like most vaccines, yellow fever vaccine is essentially a small dose of the virus, that is administered in the body of the individual. This triggers the body’s immune system to build immunity to the virus and to fight the virus. This immunity that is developed lasts for a particular period (depending on the vaccine) and offers protection to the individual. Certain vaccines for specific diseases are known to offer protection for a lifetime. It is important to note here that the yellow fever vaccine, like all vaccines is intended to be protective in nature and is not to be considered as treatment for an already developed infection.  The vaccine is generally administered atleast ten days before departure to locations that are known to expose individuals to the condition. It takes close to ten days for the immunity to develop and travel or exposure before immunity develops will not offer the required protection.

The vaccine is administered under the skin or intramuscularly. It is typically administered in a healthcare facility or a clinician’s office. The vaccine is to be taken once every ten years, especially for individuals who are exposed to the risk of coming into contact with an infected person.

Precautions that need to be followed

Individuals who intend to take the vaccine need to bear in mind that certain conditions will make it necessary to avoid the vaccine. For instance, any individual who has experienced some kind of allergy during the first dose, is not to opt for the booster dose, as this could turn out to be life endangering in nature. Similarly, those with a history of allergy to certain food products such as egg, or protein derived from chicken or gelatin are considered as unsuitable to receive the vaccine. However, people who are scheduled t travel to locations with a very high incidence of yellow fever, may still have to take the vaccine with modified dosages. This is typically achieved by lowering the dose, and scheduling multiple such doses to build immunity against the disease, while ensuring that allergies are avoided.

Patients diagnosed with cancer, or leukemia or lymphoma are also advised to stay off the vaccine, as this could trigger adverse outcomes. Similarly, certain categories of patients with a weak immune system attributed to diseases are to avoid getting vaccinated. For instance, patients with HIV or cancer are likely to have a weak immune system and the mechanism of action of the vaccine makes them unsuitable to receive the dose. Patients on steroids are also not to take the vaccine as this could result in undesirable consequences.

Other medical conditions that render the recipient unsuitable to receive the vaccine include myasthenia gravis, thymus tumor, patients whose thymus has been removed through surgery, and recipients of organ transplant. Patients who have received an organ transplant are likely to be put on medications to lower the immune response to a foreign body, and this weakened state of the body’s immune system makes the patient unsuitable for the vaccine.

What information needs to be shared with healthcare before taking the yellow fever vaccine?

It is necessary to inform healthcare facilities about certain conditions or ailments, before the vaccination. This includes any history of seizures, or any disorders that have impacted the brain. This also applies to patients who have experienced some fallout or reaction to the first dose of the vaccine. Patients diagnosed with hemophilia, blood clot, and bleeding are also to report the same to the health care facility prior to the vaccination. Depending on the condition, severity and assessment of the specialist, the vaccine may or may not be administered. Another condition that could severely react with the vaccine is Guillain Barré syndrome, a condition wherein the body’s immune system attacks the nerves. Patients with this condition are not to take the vaccine and report the same to the healthcare facility.

Patients with common cold or low-grade fever can receive the vaccine without any apprehensions of yellow fever vaccine side effects. The vaccination may be postponed only when the fever is intense or persistent; and after the conditions subside, the vaccine may be administered. Pregnant women are to seek advice from doctors before opting for vaccination, as many vaccines are known to have an impact on the fetus. Similarly, women nursing infants are to seek specialist advice about breastfeeding, as certain vaccines are known to have an impact on the health of suckling infants.

Impact of the vaccine on blood tests

The vaccine is known to have an impact on the outcomes of certain blood tests. For instance, individuals who have received the vaccine are likely to receive incorrect reports for dengue/Japanese encephalitis. It is therefore necessary for individuals who have received the vaccine to intimate the treating specialist or the diagnostic center about vaccines received in the last one and a half months.

Commonly reported undesirable effects of yellow fever vaccine

As mentioned above, the vaccine is not free from the possibility of side effects. Like all medications or vaccines, yellow fever vaccine may trigger side effects. This may be serious in nature, or mild and moderate in nature. Most individuals are unlikely to experience any unwanted outcomes, and effects may be experienced only by a small section of users. These effects may be persistent in nature or may resolve naturally depending on the nature of the effects. The following compilation of effects is neither exhaustive nor complete in nature and is only intended to serve as a broad reference to the categories.

Commonly reported yellow fever vaccine side effects include symptoms of allergic reactions. These need to be reported at the earliest, as allergies have the potential to turn into adverse conditions. For instance, vaccinated people who experience any kind of difficulty in breathing, or symptoms that are consistent with hives need medical attention. Any tightening in the chest, or swelling on the face or the throat are also indications of possible reactions. Wheezing that is abnormal, or a tightening sensation in the chest also needs to be treated at the earliest.

Remain on the lookout for certain symptoms

Caregivers and vaccinated individuals are to carefully look for signs of any of the following symptoms of undesirable outcomes. For instance, vaccinated individuals who experience unusual pain that is not attributed to any other specific reason is a cause for concern. Similarly, individuals who experience fever, or fatigue are also to be considered as experiencing possible adverse outcomes of the vaccine. There are reports of individuals feeling confused after receiving the vaccine, while some are known to have a strange, light headed feeling.

Individuals are known to end up getting bruised easily, or may bleed easily, without any strong reason. The vaccine is also known to have an impact on urination, with some individuals experiencing reduced urination. Other symptoms include a distinct yellowish appearance of the skin and the eyes, similar to that of jaundice. Any loss in appetite or vomiting sensations are to be reported to the treating specialist as this needs to be investigated to prevent it from turning into a serious outcome.

Possibility of serious side effects

While there is the possibility of serious or adverse effects from the yellow fever vaccine, the rate of occurrence is known to be extremely low or rare. Most recipients of the vaccine are free from the risks of adverse effects; however, patients are expected to check and report if any of the following symptoms are observed. For instance, if the neck unusually turns stiff in nature, or if there are symptoms of seizure, the individual is to seek medical attention. Fever that is low grade is not a reason for concern, however, high grade fever that is accompanied by any other symptom, such as vomiting could develop into a serious side effect.

Vaccinated individuals experiencing difficulties while walking is to seek advice. This also applies to vaccinated people who find it difficult to swallow food or liquid. Any impact on speech, or difficulty in coordinating or controlling eye movement is also to be considered as a possibly adverse outcome. There are other symptoms that indicate adverse outcomes – for instance, a prickly sensation in the toes or on the fingers is not to be dismissed as trivial. Similarly, any unusual weakness without any accompanying reason is also to be considered as a possibly serious outcome. Pain that is experienced only during the nights may also be experienced, and this also needs to be reported to the treating specialist.

Drug interactions of yellow fever vaccine

The vaccine may interact with certain drug combinations and formulations, and it is necessary to inform the doctor about the use of these drugs. Unlike side effects, drug interactions are common to most users and depend entirely on the drugs. The vaccine is not be administered when the patient is on Deflazacort, or Thiotepa or Trabectedin. Certain drugs are known to interact with the vaccine, but due to the critical nature of the vaccine or the medications, it may be necessary to adjust both, by modifying the intake schedule or the dosage of interacting medications.

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