Agreement: I AgreeBody: Dear Editor It is noteworthy that, at the same time that that a combined MMR and varicella vaccine (MMRV) has been included in the UK's routine immunisation schedule for children aged 12 and 18 months, it has been recommended to be removed from the USA equivalent schedule for all children under 4 years of age (1). The reason for this is a safety concern, namely that several studies have shown an approximately two-fold increase in the incidence of febrile convulsions in infants under 4 given the combined MMRV vaccine, compared to infants given the MMR and varicella vaccines separately (2). The JCVI has acknowledged that the MMRV vaccine as a first dose has been associated with a slightly increased rate of febrile seizures (3). However, the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP) recommended that toddlers continue to be immunized for varicella, but separately, rather than through the combination MMRV vaccine (1). 1https://www.hhs.gov/press-room/acip-recommends-chickenpox-vaccine-for-to... 2https://www.cdc.gov/acip/downloads/slides-2025-09-18-19/03-su-mmrv-508.pdf 3https://www.gov.uk/government/publications/childhood-varicella-vaccinati... No competing Interests: YesThe following competing Interests: Electronic Publication Date: Sunday, September 21, 2025 - 17:01AI use: No, I have not used AIHighwire Comment Subject: Chickenpox vaccine to be offered to children in EnglandWorkflow State: ReleasedFull Title: Combined MMRV vaccine now restricted to children aged 4 and older in USA Highwire Comment Response to: Chickenpox vaccine to be offered to children in EnglandCheck this box if you would like your letter to appear anonymously:: Last Name: SelleyFirst name and middle initial: Peter JohnEmail: peterjselley@gmail.comAddress: Crediton, DevonOccupation: Retired GPBMJ: Additional Article Info: Rapid response