Q.01

Has the UK withdrawn the Ixchiq chikungunya vaccine?

Yes. The MHRA has withdrawn the UK marketing authorisation for IXCHIQ, the live attenuated chikungunya vaccine. It announced this in a Drug Safety Update on 20 October 2026, after advice from the Commission on Human Medicines (CHM) led it to conclude that the vaccine's benefits no longer outweigh its risks (MHRA DSU; DSU PDF, citation: Drug Safety Update volume 20, issue 3, October 2026: 2).

Approach: I checked the EMA centralised-medicines register and official MHRA pages on GOV.UK. The datasets I can search have no UK marketing-authorisation register, so the UK status comes from the MHRA's own publications.

Why it was withdrawn (according to the DSU)

  • Since authorisation there have been reports of serious adverse reactions, including chikungunya-like symptoms and rare neurological events such as encephalitis.
  • Most cases were in older adults and people with underlying conditions, but some were in people with no known health conditions.
  • Some cases led to hospitalisation or death.
  • The MHRA reviewed the post-authorisation safety data and consulted the CHM before deciding.

What the MHRA tells healthcare professionals

  • The product is being removed from the UK market.
  • Do not prescribe, supply or give IXCHIQ, and dispose of any remaining stock under local policies. The DSU describes no formal recall process.
  • Remove IXCHIQ from any materials, systems or communications that list UK vaccination options.
  • Tell travellers about other ways to prevent chikungunya: other available chikungunya vaccines (the DSU names none), avoiding mosquito bites, and following current travel health advice.
  • Keep reporting suspected adverse reactions through the Yellow Card scheme.

What it means for people already vaccinated

  • They do not need to take any action, be revaccinated or have any medical treatment because of this decision.
  • Anyone who has had a suspected side effect should get medical advice and report it on a Yellow Card.

Earlier step: On 9 June 2025 the MHRA temporarily restricted IXCHIQ in people aged 65 and over "until a further safety review has been concluded" (MHRA news, 9 June 2025). The October 2026 withdrawal follows that review.

EU position (a separate authorisation): In the EMA register, Ixchiq (EMEA/H/C/005797) is still listed as "Authorised". It was authorised on 28/06/2024, and the entry was last updated on 24/08/2026 [1]. That entry was last updated before the UK decision.

Q.02

Why was it pulled, and what did the EMA do?

The UK withdrew Ixchiq because the MHRA, on advice from the Commission on Human Medicines, concluded that its benefits no longer outweigh its risks. The reason was serious adverse reactions, including chikungunya-like illness and rare encephalitis, some of which led to hospitalisation or death (MHRA DSU, 20 October 2026). The EMA looked at the same risks and took a different route: it kept the EU authorisation and narrowed who can be vaccinated. Ixchiq is still authorised in the EU, and I found no EU suspension or withdrawal.

Approach: I searched the EMA referrals register, the PRAC safety-signal recommendations, CHMP meeting highlights, EMA's DHPC and medicine data, and the Paul-Ehrlich-Institut's safety notices. I also opened the EMA's Ixchiq product page for its current status.

What the EMA did

  1. Article 20 safety review (EMEA/H/A-20/1540)

    • The European Commission asked for the review under Article 20 of Regulation (EC) No 726/2004. The EMA opened it on 7 May 2025 (procedure start date 08/05/2025).
    • While the review ran, Ixchiq could not be given to people aged 65 and over. A DHPC went out on 22/05/2025 [2][3].
    • The PRAC also discussed a signal of "adverse events requiring hospitalisation in elderly patients" at its 5-8 May 2025 meeting [4].

  2. Outcome: the age restriction was lifted, with a caution added

    • The PRAC made its recommendation on 10/07/2025, the CHMP endorsed it on 24/07/2025, and the Commission's decision followed on 12/09/2025.
    • The temporary ban for people aged 65 and over was removed. For all ages, the vaccine should only be given "when there is a significant risk of chikungunya infection and after a careful consideration of the benefits and risks" [2][5].
    • The evidence: 28 cases of serious side effects, mainly in people aged 65 and over or with several chronic or uncontrolled conditions (for example cardiovascular disease, diabetes or chronic kidney disease). Three of these cases were fatal. The side effects included chikungunya-like symptoms and rare encephalitis. Around 36,000 doses had been used worldwide when the review started.
    • Why the EMA kept it for older people: it judged that older people may benefit most, because they face the highest risk of severe chikungunya.
    • The existing ban on use in people with weakened immune systems stays in place [2].
    • A follow-up DHPC was sent on 23/09/2025 [6].

  3. Aseptic meningitis signal (2026)

    • The PRAC assessed a "new aspect of the known risk of aseptic meningitis". At its February 2026 meeting it did not ask for a product information update [7].
    • At its 9-12 March 2026 meeting it did ask for one [8].

  4. Narrower indication (June-July 2026)

    • At its 22-25 June 2026 meeting, the CHMP recommended limiting use to people aged 12 and over who are at high risk of catching chikungunya [9].
    • A DHPC classed as "Adverse event; Restriction of indication" followed on 14/07/2026 [10].
    • Germany's Paul-Ehrlich-Institut sent the same message in a Rote-Hand-Brief that day: use is restricted to people at high risk of chikungunya infection [11].

  5. Current EU status

    • Ixchiq (Valneva Austria GmbH, EMEA/H/C/005797) is listed as "Authorised" and is under additional monitoring.
    • Its indication is now for people aged 12 and over "at high risk of acquiring chikungunya infection". The latest Commission decision is dated 17/08/2026 and the entry was last updated on 24/08/2026 [12].
    • The EMA's Ixchiq page shows the same status and date, with nothing posted since the MHRA's 20 October 2026 decision.

How the two decisions differ: both regulators looked at the same kinds of harm, mostly in older adults and people with other illnesses. The EU has managed the risk with warnings and a high-risk-only indication. The MHRA decided that no group of patients has a positive benefit-risk balance. The UK DSU, unlike the EMA's 2025 review, notes that some cases occurred in people with no known health conditions.

Q.03

What about the US?

Yes. The US acted before both the UK and the EU, and Ixchiq has no US licence today. The FDA suspended Valneva's biologics licence on 22 August 2025 because of serious safety concerns. The licence was then revoked at Valneva's own request, with a withdrawal date of 29 January 2026. The September 2026 edition of the FDA Purple Book lists IXCHIQ (BLA 125777) with licensure "Revoked" and marketing status "Disc" [13].

Approach: I searched the FDA Purple Book, CBER's register of biologics approvals, FDA's postmarketing requirements database and openFDA recalls, then opened the FDA and CBER safety and withdrawal pages on fda.gov. I found no DailyMed label for IXCHIQ, and the FDA's revocation letter could not be opened.

US timeline

DateAction
9 Nov 2023CBER approved BLA 125777 under accelerated approval, for adults 18 and over at increased risk of exposure to chikungunya [14]
9 May 2025The FDA and CDC recommended pausing use in people aged 60 and over while reports were investigated (FDA notice)
6 Aug 2025The FDA lifted the pause for people 60 and over but required updated labelling, with stronger warnings for people 65 and over with chronic conditions (FDA safety communication)
22 Aug 2025CBER suspended the biologics licence (same communication)
Jan 2026Valneva stopped making IXCHIQ and asked for its US licence to be voluntarily revoked (CBER permanent discontinuations)
29 Jan 2026Listed as withdrawn on FDA's accelerated-approvals page. The two open postmarketing requirements were released when it was withdrawn (FDA withdrawn accelerated approvals)

Why the FDA acted

  • May 2025 pause: as of 7 May 2025 there were 17 serious adverse events in recipients aged 62-89, including two deaths, one of them from encephalitis. Six of the reports were from the US. Most people affected had chronic underlying conditions, and about 80,000 doses had been distributed worldwide.
  • August 2025 suspension: the FDA cited:
    • one death from encephalitis caused by the vaccine strain, confirmed by PCR testing of cerebrospinal fluid;
    • more than 20 serious adverse events consistent with chikungunya-like illness, with 21 hospitalisations and 3 deaths in total;
    • the fact that confirmatory studies had not verified clinical benefit.
  • Conclusion: the FDA said the vaccine "does not have benefits outweighing risks, under most plausible scenarios" and was "a danger to health".

How the US compares with the UK and EU

  • The FDA's action was the most severe and came first: it suspended the licence about 14 months before the MHRA's withdrawal in October 2026.
  • The EU has kept the authorisation, with a high-risk-only indication.
  • Unlike the other two regulators, the FDA also relied on the accelerated-approval basis: clinical benefit had still not been confirmed.

Other chikungunya vaccine in the US: VIMKUNYA (Chikungunya Vaccine, Recombinant; Bavarian Nordic, BLA 125820) is licensed and on prescription. It was approved on 14 Feb 2025 for people aged 12 and over [15][16]. It also had accelerated approval: a required efficacy study is ongoing, with its final report due 31 August 2030 [17].

Q.04