Chikungunya virus, strain CHIKV LR2006-OPY1, live attenuated

Table of contents

• What is chikungunya virus, strain CHIKV LR2006-OPY1, live attenuated?
• How does chikungunya virus, strain CHIKV LR2006-OPY1, live attenuated work?
• Which conditions is it used or studied for?
• How is chikungunya virus, strain CHIKV LR2006-OPY1, live attenuated given?
• What do the clinical trials show?
• What side effects are known?

What is chikungunya virus, strain CHIKV LR2006-OPY1, live attenuated?

Chikungunya virus, strain CHIKV LR2006-OPY1, live attenuated is a live, weakened form of the chikungunya virus. It is the active substance in the vaccine Ixchiq, which is authorised for use in the European Union.^[2] The vaccine is produced by Valneva Austria GmbH.^[1] In the EU clinical trial registry, the substance is recorded as a solution for injection given by intramuscular injection.^[1] The product is also known as Chikungunya vaccine (live).^[1]

How does chikungunya virus, strain CHIKV LR2006-OPY1, live attenuated work?

Ixchiq works as a vaccine. Vaccines prepare the immune system, the body's natural defences, to defend against a specific disease. The vaccine contains a strain of chikungunya virus that has been attenuated, meaning weakened. When a person receives the vaccine, the immune system recognises the weakened virus as foreign and produces antibodies against it. If the person later comes into contact with the chikungunya virus, the immune system can fight off the virus more effectively, helping to protect against chikungunya disease.^[2]

Which conditions is it used or studied for?

• Chikungunya — a viral disease that mosquitoes can pass to humans. The vaccine is used to help protect people aged 12 years and older who are at high risk of becoming infected with the chikungunya virus.^[2]

How is chikungunya virus, strain CHIKV LR2006-OPY1, live attenuated given?

The vaccine is given as one injection into the muscle of the upper arm. It can only be obtained with a prescription and should be used according to official recommendations issued at national level by public health bodies.^[2] The pharmaceutical form is a solution for injection.^[1] The trial in La Réunion uses a dose of 0.50 ml given by intramuscular injection.^[1]

What do the clinical trials show?

One Phase 3 trial is evaluating the real-life effectiveness of the chikungunya vaccine in La Réunion.^[1] The trial is an ambispective study, meaning it looks both forward and backward in time. It includes 1,800 participants who are at risk of severe or complicated chikungunya disease.^[1]

The trial measures vaccine effectiveness (EV) at 6 months. Vaccine effectiveness is defined as the difference in attack rate between unvaccinated and vaccinated participants, divided by the attack rate in unvaccinated participants. The attack rate corresponds to the cumulative incidence, or percentage of participants who develop the disease, at the end of the study follow-up period. Follow-up is assessed at an interim analysis at 3 months at the end of the hot season, and then at the end of full follow-up at 12 months, starting from 7 days after vaccination for the vaccinated group.^[1]

Confirmed chikungunya is defined by a positive PCR test or IgM antibodies in a participant not previously immunized during the epidemic phase. The trial status is Authorised, meaning the trial has received approval to proceed.^[1]

What side effects are known?

The European Medicines Agency (EMA) has authorised Ixchiq for use in the European Union. The EMA provides patient safety information for this medicine.^[2] Vaccinated people should continue to apply personal protection measures against mosquito bites after vaccination, including the use of mosquito repellents and nets, wearing clothing that covers most of the body, and sleeping in screened or air-conditioned rooms.^[2]