On October 20, 2026, the UK regulatory agency (MHRA) announced, in its Drug Safety Update, the withdrawal of the marketing authorization of the IXCHIQ chikungunya vaccine, held by Valneva. In the Brazilian context, Instituto Butantan acts in partnership with Valneva and holds the marketing authorization and the local manufacturing authorization, both approved by ANVISA.

The MHRA decision followed the advice of the Commission on Human Medicines (CHM), an advisory public body in the United Kingdom, sponsored by the Department of Health and Social Care, and rests on the conclusion that the benefit-risk balance of the product is no longer favorable. The vaccine is being removed only from the UK market.

A few days before the MHRA’s decision, Valneva had already published an update regarding the situation in the UK, clarifying that this withdrawal does not affect marketing authorizations approved in other territories, such as the European Union, Canada, and Brazil.

What motivated the decision

IXCHIQ is a live attenuated vaccine indicated for the prevention of chikungunya virus infection in adults traveling to high-risk areas. According to the MHRA, the review of post-authorization safety data identified serious adverse reactions, including chikungunya-like symptoms and rare neurological events such as encephalitis. The cases occurred predominantly in older adults and in people with underlying medical conditions, but also in individuals with no other known conditions, and some resulted in hospitalization or death. On this basis, the Agency concluded that, for UK travelers, the benefits of the vaccine no longer outweigh the risks.

Advice to healthcare professionals

The MHRA advises UK healthcare professionals to:

• Not prescribe, supply or administer the vaccine, and dispose of any remaining stock in accordance with local policies.
• Update materials, systems and communications that refer to the vaccination options available in the UK.
• Advise travelers on alternatives, such as other chikungunya vaccines, protection against mosquito bites and adherence to health-related travel advice.
• Continue reporting suspected adverse reactions through the Yellow Card scheme.

Individuals who have already received the vaccine and had no reactions do not need revaccination or any other intervention. Those who experienced adverse effects should seek medical advice and report the case.

International landscape and the situation in Brazil

The decision adds to measures taken by other authorities.

In the United States, the FDA suspended the vaccine license in August 2025, and Valneva announced in January 2026 the voluntary withdrawal of its biologics license application in the country.

In Brazil, ANVISA approved IXCHIQ in April 2025 and, in May 2026, authorized local manufacturing by Instituto Butantan, with an indication for people aged 18 to 59 years at increased risk of exposure to the virus. The Agency also published Pharmacovigilance Alert 03/2026, with an update of the indication and safety information of the vaccine.

Each authority assesses the benefit-risk balance in its own context, and the MHRA decision refers to the UK market. According to Valneva’s release, other markets are not affected.

Implications for marketing authorization holders

The case shows how post-authorization pharmacovigilance data can lead to decisions such as indication restrictions and withdrawal of an authorization, at different moments in each authority, depending on the population context of each jurisdiction. For marketing authorization holders (MAHs) of vaccines and other products under intensive monitoring, it is worth maintaining structured processes for signal detection and assessment, for following the decisions of reference authorities and for assessing the impact on indications, package leaflets, communications to healthcare professionals and stock management.

Vita follows decisions of this kind and supports companies in assessing the regulatory impact and in handling the resulting post-approval changes.