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Scientists comment on news that the CDD vaccine advisory committee has changed its MMRV vaccine recommendation.
Prof Jonathan Ball, Deputy Vice-Chancellor, Liverpool School of Tropical Medicine; and Professor of Molecular Virology, Liverpool School of Tropical Medicine (LSTM), said:
“We have a sensible policy in MMRV vaccines, a policy based on evidence not anecdotes.
“Since it’s production, the MMR vaccine has without doubt saved lives and prevented serious disease, including life changing disease in vulnerable newborns and infants.
“I am sure our own policy advisors will stay firm and continue to recommend the combined vaccine. Vaccine hesitancy is a massive problem and mandating the giving of separate doses of each vaccine component will complicate immunisation schedules, increase inconvenience – known to be a big driver in non-uptake – and therefore drive down protection.”
Dr Ben Kasstan-Dabush, Assistant Professor, Department of Global Health & Development at LSHTM, said:
“There were close to 3,000 laboratory confirmed cases of measles in England in 2024, outbreaks continued into 2025 and led to the death of a child. Similar patterns have occurred in the U.S, with two child deaths linked to measles in 2025. The deaths and majority of these cases of sickness in the UK and US were in unvaccinated children, reminding us that the MMR vaccine has been given to generations of children for over 40 years because of its record of safety and effectiveness.
“The decision by the US vaccine committee appears to be less about reviewing evidence than re-envisioning evidence. Consensus on evidence is critical for healthcare practitioners to recommend vaccines and for parents to feel confident that those recommendations are in place to protect their children. While bodies such as the West Coast Health Alliance are moving to offer evidence-based recommendations and push back against Kennedy’s actions, I worry about those parents trying to make sense of diverging public health recommendations at state and federal levels.
“Countries usually vary in the immunisation schedules that they offered parents, and variation in itself is not a problem for parents in the UK. The issue in this case is the potential to disorient public opinion. From 2026, the NHS routine immunisation schedule will change, and parents will be offered the second dose of MMR at 18 months instead of 3 years and four months, and a varicella (chickenpox) component will be added. Communities with low uptake of MMR vaccination must be prepared ahead of the schedule change, particularly diaspora communities with transnational links to the US due to the international flows of misinformation. I am deeply concerned about the ability to work with communities, by co-producing communications with community partners, when NHS Integrated Care Boards are expected to slash their operational costs by as much as 50%.”
Adam Finn, Professor of Paediatrics, University of Bristol, said:
“The recommendation to give separate MMR and V injections rather than a single combined MMRV reflects prioritisation of prevention of side effects over prevention of disease. Children given separate vaccines are marginally less likely to experience febrile convulsions – a rare, unpleasant but ultimately harmless consequence of the fever that accompanies the mild infections that the vaccine can cause. But giving two injections instead of one causes twice the discomfort and distress caused by injections for the child and operationally results in fewer children overall getting protected against all four diseases, a disadvantage both for them and for the programme and so brings an increased risk that cases will continue to occur. It also means more time and trouble for parents and more work for stretched health services. For all these reasons, policy recommendations in countries including the UK have been trending towards using the combined MMRV option for both doses while this decision goes in the opposite direction. Frankly, it’s not an outrageous decision and there is a case that can be made in support of it, but it probably will reduce the overall efficiency and impact of the US programme.”
Declared interests
Adam Finn undertakes paid consultancy for multiple vaccine developers and manufacturers including those that make MMR V and MMRV vaccines, although that work is not related to these vaccines.
Ben Kasstan: No competing interests to declare.
Prof Jonathan Ball: Work on preclinical development of vaccines, but do not receive funding from industry for this.