Summary of the safety profile
The overall safety of IXCHIQ is based on an analysis of the pooled safety data from three completed phase I and III clinical studies conducted in the US on 3 610 participants ≥18 years old who received one dose of IXCHIQ with a follow-up of 6 months.
The most common vaccination site reactions were tenderness (10.8%) and pain (6.1%). The most common systemic adverse reactions were headache (32%), fatigue (29.4%), myalgia (23.7%), arthralgia (16.6%), fever (13.8%) and nausea (11.4%).
IXCHIQ must not be used in individuals 60 years and older (see section 4.1)
In the post-marketing setting, serious adverse reactions have been reported, particularly in males aged 65 years and older with underlying chronic medical conditions such as cardiovascular disease, diabetes mellitus or chronic kidney disease. These adverse reactions included neurological events such as fatal encephalitis, deterioration of general condition, and exacerbation of chronic medical conditions (see section 4.4).
Laboratory parameters
The most common abnormal laboratory parameters were neutropenia (41.8%), leukopenia (31.2%), lymphopenia (22.3%), Alanine aminotransferase increased (ALT: 15.5%), and Aspartate aminotransferase increased (AST: 11.7%) (based on an immunogenicity subset of 372 IXCHIQ recipients).
Vaccine Viraemia and Shedding
Vaccine virus was demonstrated to be present in blood and urine and might be present in other body fluids. Vaccine viraemia and shedding (measured by genomic amplification methods) following vaccination with IXCHIQ was assessed in one adult clinical trial (VLA1553-101). Viraemia was detected in 90% of subjects 3 days after vaccination, proportions of vaccinees with detectable virus declined to 17% by 7 days after administration of IXCHIQ and no vaccine viraemia was detected 15 days after vaccination. A single participant shed vaccine virus in urine 7 days after vaccination.
Tabulated list of adverse reactions
Adverse reactions are listed according to the following frequency categories:
Very common: (≥ 1/10),
Common: (≥ 1/100 to < 1/10),
Uncommon: (≥ 1/1 000 to < 1/100),
Rare: (≥ 1/10 000 to < 1/1 000),
Very rare: (<1/10 000),
Not known: (cannot be estimated from available data).
Within each frequency grouping the adverse reactions are presented in the order of decreasing seriousness.
Table 1. Adverse reactions in individuals 18 years of age and older
| System organ class | Frequency | Adverse reactions |
| Blood and lymphatic system disorders | Common | Lymphadenopathy |
| Uncommon | Thrombocytopenia |
| Endocrine disorders | Rare | Hypovolaemic hyponatraemia |
| Nervous system disorders | Very common | Headache |
| Common | |
| Uncommon | Dizziness, paraesthesia, syncope |
| Rare | Confusional state |
| Not known | Encephalopathy, encephalitis, aseptic meningitis. |
| Eye disorders | Uncommon | Eye pain |
| Ear and labyrinth disorders | Uncommon | Tinnitus |
| Respiratory, thoracic and mediastinal disorders | Uncommon | Dyspnoea |
| Gastrointestinal disorders | Very common | Nausea |
| Common | Vomiting, diarrhoea |
| Skin and subcutaneous tissue disorders | Common | Rash |
| Uncommon | Hyperhidrosis |
| Musculoskeletal and connective tissue disorders | Very common | Myalgia, arthralgia |
| Common | Back pain |
| General disorders and administration site conditions | Very common | Fatigue, fever, vaccination site reactions (tenderness, pain, erythema, induration, swelling) |
| Common | Chills |
| Uncommon | Asthenia, oedema peripheral, malaise, decreased appetite |
| Investigations | Very common | White blood cell count decreased*; liver function test increased** |
*. includes: leukopenia (leukocyte decreased), neutropenia (neutrophil decreased) and lymphopenia (lymphocyte decreased).
**. includes: Alanine aminotransferase increased (ALT) and Aspartate aminotransferase increased (AST).
Chikungunya-like Adverse Reactions
The occurrence of certain adverse event combinations, referred to as chikungunya-like adverse reactions, was retrospectively evaluated in the pooled safety data from phase I and III clinical studies (N=3 610). Chikungunya-like adverse reactions were broadly defined, i.e. occurrence of fever (≥38°C) and at least one other symptom also reported for acute-stage chikungunya illness, including arthralgia or arthritis, myalgia, headache, back pain, rash, lymphadenopathy, and certain neurological, cardiac or ocular symptoms; within 30 days after vaccination, regardless of time of onset, severity or duration of the individual symptoms.
Adverse event combinations qualifying as chikungunya-like adverse reactions were reported in 12.1% of participants. Among those, combinations of fever with headache, fatigue, myalgia or arthralgia were the most common, all other symptoms were reported in fewer than 10% of chikungunya-like adverse reactions. The reported symptoms were mostly mild, 1.8% of participants reported at least one severe symptom, most commonly fever or arthralgia. Median onset of chikungunya-like adverse reactions was 3 days after vaccination, and median time to resolution was 4 days. Longer-lasting symptoms ≥30 days occurred in 0.4% of participants.
Paediatric population
Safety in adolescent participants ≥12 years was assessed in 502 participants in Brazil who received one dose of IXCHIQ with a follow-up of 28 days. Approximately 20% of the participants had pre-existing antibodies against chikungunya virus. The proportion of participants that experienced solicited systemic AEs and Chikungunya-like adverse reactions was higher in seronegative participants at baseline vaccinated with VLA1553 (67.9% and 27.2%, respectively) than in seropositive participants at baseline vaccinated with VLA1553 (44.7% and 6.4%, respectively). The proportion of participants who experienced solicited local AEs and unsolicited AEs was similar in the VLA1553 arms of each stratum.”
Reporting of suspected adverse reactions
If you are concerned about an adverse event, it should be reported on a Yellow Card. Reporting forms and information can be found at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store and include the vaccine brand and batch/Lot number if available.
Alternatively, adverse events of concern in association with IXCHIQ can be reported to Valneva Austria GmbH on +43 1 20620 1444 or email to [email protected].
Please do not report the same adverse event(s) to both systems as all reports will be shared between Valneva Austria GmbH and the MHRA (in an anonymised form) and dual reporting will create unnecessary duplicates.