Medical Editor: John P. Cunha, DO, FACOEP
YF-Vax (yellow fever vaccine) is a vaccine used to help prevent yellow fever in adults and children who are at least 9 months old. Yellow fever is spread through the bite of an infected mosquito. YF-Vax is recommended for people who plan travel to areas where yellow fever is known to exist, for people who work in a research laboratory, or anyone otherwise at high risk of coming into contact with the virus. YF-Vax is available in generic form. Common side effects of YF-Vax (may occur for 5 to 10 days after receiving the vaccine) include injection site reactions (redness, pain, swelling, tenderness, soreness, aches, or a lump), fever, joint pain, body aches, muscle pain, flu-like symptoms, rash, headache, or general ill feeling (malaise). Tell your doctor if you experience serious side effects of YF-Vax (may occur up to 30 days after you receive the vaccine) including stiff neck or back, vomiting, confusion, memory loss, irritability, loss of balance or coordination; weakness or prickly feeling in your fingers or toes, sensitivity to light; problems with walking, breathing, speech, swallowing, vision, or eye movement; severe lower back pain, loss of bladder or bowel control; muscle weakness or loss of movement in any part of your body; behavior changes, or seizures (black-out or convulsions).
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Get emergency medical help if you have signs of an allergic reaction: hives; wheezing, chest tightness, difficult breathing; swelling of your face, lips, tongue, or throat.
You should not receive a booster vaccine if you had a life-threatening allergic reaction after the first vaccine. Keep track of any and all side effects that occur within 30 days after you receive this vaccine. If you ever need to receive a booster dose, you will need to tell your doctor if the previous shot caused any side effects.
Seek medical attention right away if you have any of these symptoms similar to yellow fever that may occur within 10 days after vaccination:
- fever, headache, confusion, extreme tiredness;
- muscle pain or weakness;
- a light-headed feeling, like you might pass out;
- easy bruising, unusual bleeding;
- little or no urination; or
- vomiting, loss of appetite, jaundice (yellowing of the skin or eyes).
Becoming infected with yellow fever is much more dangerous to your health than receiving this vaccine. However, like any medicine, this vaccine can cause side effects but the risk of serious side effects is extremely low.
Call your doctor at once if you have any of these rare but serious side effects within 10 days after you receive the vaccine:
- high fever, vomiting, increased sensitivity to light;
- extreme tiredness, neck stiffness, seizure;
- problems with walking, breathing, speech, swallowing, vision, or eye movement;
- weakness or prickly feeling in your fingers or toes;
- severe pain (especially at night); or
- loss of bladder or bowel control.
Serious side effects may be more likely in older adults.
Common side effects (may occur within 5 to 10 days after vaccination) include:
- low fever, general ill feeling;
- mild headache, muscle pain;
- weakness; or
- pain, swelling, or a lump where the shot was given.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report vaccine side effects to the US Department of Health and Human Services at 1-800-822-7967.
Read the entire detailed patient monograph for Yellow Fever Vaccine (Yellow Fever Vaccine)
Data From Clinical Studies
Adverse reactions to YF-VAX include mild headaches, myalgia, low-grade fevers, or other minor symptoms for 5 to 10 days. Local reactions including edema, hypersensitivity, pain or mass at the injection site have also been reported following yellow fever vaccine administration. Immediate hypersensitivity reactions, characterized by rash, urticaria, and/or asthma, occur principally among persons with histories of allergy to eggs or other substances contained in the vaccine.
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a vaccine cannot be directly compared to rates in the clinical trials of another vaccine and may not reflect the rates observed in practice.
No placebo-controlled trial has assessed the safety of YF-VAX. However, between 1953 and 1994, reactogenicity of 17D-204 vaccine was monitored in 10 uncontrolled clinical trials. The trials included a total of 3,933 adults and 264 infants greater than 4 months old residing in Europe or in yellow fever endemic areas. Self-limited and mild local reactions consisting of erythema and pain at the injection site and systemic reactions consisting of headache and/or fever occurred in a minority of subjects (typically less than 5%) 5 to 7 days after immunization. In one study involving 115 infants age 4 to 24 months the incidence of fever was as high as 21%. Also in this study, reactogenicity of the vaccine was markedly reduced among a subset of subjects who had serological evidence of previous exposure to yellow fever virus. Only two of the ten studies provided diary cards for daily reporting; this method resulted in a slightly higher incidence of local and systemic complaints. YF-VAX was used as a control in a double-blind, randomized comparative trial with another 17D-204 vaccine, conducted at nine centers in the US. YF-VAX was administered to 725 adults ≥ 18 years old with a mean age of 38 years. Safety data were collected by diary card for days 1 through 10 after vaccination and by interview on days 5, 11, and 31. Among subjects who received YF-VAX, there were no serious adverse events, and 71.9% experienced non-serious adverse events judged to have been related to vaccination. Most of these were injection site reactions of mild to moderate severity. Four such local reactions were considered severe. Rash occurred in 3.2%, including two subjects with urticaria. Systemic reactions (headache, myalgia, malaise, and asthenia) were usually mild and occurred in 10% to 30% of subjects during the first few days after vaccination. The incidence of non-serious adverse reactions, including headache, malaise, injection site edema, and pain, was significantly lower in subjects > 60 years compared to younger subjects. Adverse events were less frequent in the 1.7% of vaccinated subjects who had pre-existing immunity to yellow fever virus, compared to those without pre-existing immunity. (8)
Data From Post-marketing Experience
The following additional adverse events have been spontaneously reported during the post-marketing use of YF-VAX worldwide. Because these events are reported voluntarily from a population of uncertain size, it is not possible to estimate their frequency reliably or establish a causal relationship to vaccine exposure. This list includes adverse events based on one or more of the following factors: severity, frequency of reporting, or strength of evidence for a causal relationship to YF-VAX.
- Immune System Disorders (14)
Immediate hypersensitivity reactions or anaphylaxis, characterized by rash and/or urticaria and/or respiratory symptoms (e.g., dyspnea, bronchospasm, or pharyngeal edema) occur principally among persons with histories of allergies to egg or other substances contained in the vaccine.
- Nervous System Disorders(1) (32) (33) (34)
Isolated cases of Yellow Fever Vaccine-Associated Neurotropic Disease (YEL-AND), sometimes fatal, have been reported to occur within 30 days following vaccination with YF-VAX, and other yellow fever vaccines (see WARNINGS section, Yellow fever vaccine-associated neurotropic disease subsection). Age less than 9 months and congenital or acquired immunodeficiency have been identified as risk factors for this event. (See WARNINGS and CONTRAINDICATIONS sections.) Twenty-one cases of YEL-AND associated with all licensed 17D vaccines have been reported between 1952 and 2004. Eighteen of these cases were in children or adolescents. Fifteen of these cases occurred prior to 1960, thirteen of which occurred in infants 4 months of age or younger, and two of which occurred in infants six and seven months old. The incidence of vaccineassociated neurologic disease in infants less than 4 months old is estimated to be between 50 and 400 cases per 1,000,000, based on two historical reports where denominators are available. (33) (34) (35) A study in Senegal (34) described two fatal cases of encephalitis possibly associated with 17D-204 vaccination among 67,325 children between the ages of 6 months and 2 years, for an incidence rate of 3 per 100,000. The incidence of YEL-AND in the United States is less than 1:100,000 doses administered. (17)
Other neurological complications have included Guillain-Barre syndrome (GBS), acute disseminated encephalomyelitis (ADEM), and bulbar palsy.
- Infections and infestations
Isolated cases of Yellow Fever Vaccine-Associated Viscerotropic Disease YEL-AVD, formerly described as “Febrile Multiple Organ-System-Failure”), sometimes fatal, have been reported following YF-VAX and other yellow fever vaccines (see WARNINGS section, Yellow fever vaccine-associated viscerotropic disease subsection). In the majority of cases reported, the onset of signs and symptoms was within 10 days after the vaccination. Initial signs and symptoms are non-specific and may include pyrexia, myalgia, fatigue and headache, potentially progressing quickly to liver and muscle cytolysis and possibly to thrombocytopenia, lymphopenia and acute renal failure.(18) The pathophysiological mechanism of such reactions has not been established. In some individuals with YEL-AVD a medical history of thymic disease has been reported. (36) Age older than 60 has also been identified as a risk factor for this event. (9) During surveillance in the U.S. between 1996 and 1998, four individuals (ages 63, 67, 76, and 79) became severely ill 2 to 5 days after vaccination with YF-VAX vaccine. Three of these 4 subjects died. The incidence rate for these serious adverse events was estimated at 1 per 400,000 doses of YF-VAX vaccine, based on the total number of doses administered in the U.S. civilian population during the surveillance period. (21) YEL-AVD has occurred after yellow fever vaccination in fewer than 1:100,000 U.S. vaccinees, (14) most commonly in individuals 60 years of age and older.
In a CDC analysis of data submitted to the Vaccine Adverse Events Reporting System (VAERS) between 1990 and 1998, the rate of systemic adverse events following vaccination was 2.5-fold higher in the 65 years or older age group (6.2 events per 100,000 doses of vaccine) compared to the 25 to 44 year-old age group (2.5 events per 100,000 doses of vaccine). (31)
Reporting Of Adverse Events
To report SUSPECTED ADVERSE REACTIONS, contact the Pharmacovigilance Department, Sanofi Pasteur Inc., Discovery Drive, Swiftwater, PA 18370 at 1-800-822-2463 (1-800-VACCINE) or VAERS at 1-800-822-7967 or https://vaers.hhs.gov.
Read the entire FDA prescribing information for Yellow Fever Vaccine (Yellow Fever Vaccine)