The safety and tolerability of IXCHIQ were evaluated in 2 clinical studies1*

Percentage of participants with solicited local and systemic adverse reactions within 10 days after vaccination (Study 1)1

Solicited injection site adverse reactiona IXCHIQ (N=3,082), % Placebo (N=1,033), %
Tenderness (any)b 10.6 8.1
Tenderness (severe) 0 0
Pain (any)c 6.2 3.7
Pain (severe) 0.03 0
Erythema/redness (≥2.5 cm)d 1.5 1.5
Induration (≥2.5 cm)d 1.4 0.8
Swelling (≥2.5 cm)d 0.7 0.8
Solicited systemic adverse reactiona IXCHIQ (N=3,082), % Placebo (N=1,033), %
Headache (any)a 31.6 14.7
Headache (severe)e 0.1 0.1
Fatigue (any)a 28.5 12.7
Fatigue (severe)e 0.2 0
Myalgia/muscle pain (any)a 23.9 7.4
Myalgia/muscle pain (severe)e 0.3 0
Arthralgia/joint pain (any)a 17.2 4.9
Arthralgia/joint pain (severe)e 0.3 0
Fever (any)f 13.5 0.9
Fever (severe or worse)g 1.4 0
Nausea (any)a 11.2 5.6
Nausea (severe)e 0 0.1
Rash (any)a 2.3 0.5
Rash (severe)h 0 0
Vomiting (any)a 1.9 1.0
Vomiting (severe)e 0 0.1

N=number of participants. aSeverity=mild, moderate, severe intensity. bDefined as mild (mild discomfort to touch), moderate (discomfort with movement), severe (significant discomfort at rest). Any potentially life-threatening event (emergency room visit or hospitalization) was to be reported as severe. cDefined as mild (does not interfere with activity), moderate (repeated use of non-narcotic pain reliever >24 hours or interferes with activity), severe (any use of narcotic pain reliever or prevents daily activity). Any potentially life-threatening event (emergency room visit or hospitalization) was to be reported as severe. dNo participants had erythema, induration, or swelling >10 cm. eSevere=prevents daily activity (for fatigue, myalgia, and arthralgia); prevents daily activity and requires medical intervention (for headache, nausea, vomiting). fDefined as temperature ≥38.0°C (100.4°F). gDefined as temperature ≥39.0°C (102.1°F). hSevere=macules/papules covering >30% body surface area with or without associated symptoms; limiting self-care activity of daily living.

*Study 1 was a randomized, placebo-controlled, double-blinded study in which participants were vaccinated with a single dose of IXCHIQ (N=3,082) or placebo (Phosphate Buffered Saline) (N=1,033).

Frequency of chikungunya-like symptoms among participants with chikungunya-like adverse reactions (Study 1)1

In Study 1, chikungunya-like adverse reactions were monitored through 6 months post vaccination. Chikungunya-like adverse reactions were defined as fever (≥100.4°F) and one or more of any of the following: arthralgia or arthritis, myalgia, headache, back pain, rash, lymphadenopathy, or certain neurological, cardiac, or ocular symptoms that occurred with an onset within 30 days after vaccination. Severe chikungunya-like adverse reactions were those that prevented daily activity and/or required medical intervention. Among Study 1 participants who received IXCHIQ (n=3,082), 361 reported chikungunya-like adverse reactions.

Chikungunya-like symptom
Chikungunya-like symptom (severe)
IXCHIQ (N=361)
% (n)
Pyrexia (any) 100 (361)
Pyrexia (severe) 10.8 (39)
Headache (any) 77.6 (280)
Headache (severe) 0.3 (1)
Fatigue (any) 73.1 (264)
Fatigue (severe) 0.6 (2)
Myalgia (any) 59.6 (215)
Myalgia (severe) 0.8 (3)
Arthralgia (any) 44.0 (159)
Arthralgia (severe) 1.4 (5)
Chills (any)a 8.0 (29)
Rash (any)a 6.1 (22)
Back pain (any) 3.6 (13)
Back pain (severe) 0.3 (1)
Lymphadenopathy (any)a 2.5 (9)
Dizziness (any)a 1.7 (6)
Pain (any)a 1.1 (4)
Paresthesia (any)a 0.8 (3)
Hyperhidrosis (any)a 0.6 (2)
Edema peripheral (any)a 0.6 (2)
Asthenia (any)a 0.3 (1)
Ataxia (any)a 0.3 (1)
Atrial fibrillation (any) 0.3 (1)
Atrial fibrillation (severe) 0.3 (1)
Feeling abnormal (any)a 0.3 (1)
Hypoesthesia (any)a 0.3 (1)
Influenza like illness (any)a 0.3 (1)
Neuropathy peripheral (any)a 0.3 (1)
Rash erythematous (any)a 0.3 (1)
Syncope (any)a 0.3 (1)

N=number of participants with chikungunya-like adverse reactions; n=number of participants with chikungunya-like symptom.

aNo severe chikungunya-like symptoms reported.

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Reference: 1. IXCHIQ. Prescribing information. Valneva USA Inc.; 2023.


IXCHIQ is a vaccine indicated for the prevention of disease caused by chikungunya virus (CHIKV) in individuals 18 years of age and older who are at increased risk of exposure to CHIKV.

This indication is approved under accelerated approval based on anti-CHIKV neutralizing antibody levels. Continued approval for this indication may be contingent upon verification and description of clinical benefit in confirmatory studies.


ContraindicationsDo not administer IXCHIQ to individuals who are immunodeficient or immunosuppressed due to disease or medical therapy (e.g., from hematologic and solid tumors, receipt of chemotherapy, congenital immunodeficiency, long-term immunosuppressive therapy or patients with HIV infection who are severely immunocompromised), or to individuals with a history of a severe allergic reaction to any component of the vaccine.

Warnings and PrecautionsAppropriate medical treatment used to manage immediate allergic reactions must be available in the event an acute anaphylactic reaction occurs following administration of IXCHIQ.

Vaccination with IXCHIQ may cause severe or prolonged chikungunya-like adverse reactions. Severe chikungunya-like adverse reactions that prevented daily activity and/or required medical intervention occurred in 1.6% of 3,082 IXCHIQ recipients and no placebo recipients. Fourteen IXCHIQ recipients had prolonged (duration at least 30 days) chikungunya-like adverse reactions.

Potential for vertical transmission of vaccine virus and fetal/neonatal adverse reactions. Vertical transmission of wild-type CHIKV from pregnant individuals with viremia at delivery is common and can cause potentially fatal CHIKV disease in neonates. It is not known if the vaccine virus can be vertically transmitted and cause fetal or neonatal adverse reactions. Decisions to administer IXCHIQ during pregnancy should take into consideration the individual’s risk of exposure to wild-type CHIKV, gestational age, and risks to the fetus or neonate from vertical transmission of wild-type CHIKV.

Syncope can occur with administration of IXCHIQ. Procedures should be in place to avoid injury from fainting.

IXCHIQ may not protect all individuals who receive the vaccine.

Adverse Reactions In clinical studies, the most common injection site reaction (>10%) was tenderness (11%). The most common systemic adverse reactions (>10%) were headache (32%), fatigue (29%), myalgia (24%), arthralgia (17%), fever (14%), and nausea (11%).

Use in Specific Populations PregnancyThere is a pregnancy registry to monitor outcomes in women exposed to IXCHIQ during pregnancy and it may be reached by contacting OXON Epidemiology at 1-855-417-6214. There are no adequate and well-controlled studies of IXCHIQ in pregnant individuals, and human data available from clinical trials with IXCHIQ are insufficient to establish the presence or absence of vaccine-associated risk during pregnancy.

To report SUSPECTED ADVERSE REACTIONS, contact Valneva at 1-844-349-4276 or VAERS at 1-800-822-7967 or

Please click here to see full Prescribing Information.