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Two nations, two completely different approaches to defending youngsters from chickenpox. Whereas the UK prepares to introduce a mixed vaccine masking measles, mumps, rubella and chickenpox (MMRV) in a single jab, the US is shifting in the wrong way—proscribing mother and father’ means to decide on that very same mixture for his or her youngest youngsters.
Simply because the US has simply celebrated 30 years of chickenpox vaccination, advisers to its well being secretary, Robert F. Kennedy Jr, voted in opposition to the usage of the MMRV vaccine for kids below 4 years outdated. In the meantime, from January 2026, the UK will supply youngsters their first dose of the mixed MMRV vaccine at 12 months and a second dose at 18 months outdated.
This divergence displays extra than simply completely different medical opinions; it highlights how the political local weather can form well being coverage. In June 2025, RFK Jr dismissed all members of the US Advisory Committee on Immunization Practices and changed them with advisers who’ve made a collection of suggestions proscribing vaccination within the US.
At present, youngsters within the US obtain two doses of measles, mumps, rubella and chickenpox (varicella) vaccines—the primary at 12–15 months, and the second at 4 to 6 years outdated. For the primary dose, separate chickenpox and MMR vaccines are suggested except mother and father desire the mixed shot. The brand new restrictions would get rid of that parental alternative.
The US panel’s concern is about febrile seizures—suits attributable to excessive temperatures that may happen in younger youngsters after vaccination. Chickenpox (also referred to as varicella) vaccine might be delivered as a standalone vaccine, or mixed with measles, mumps and rubella in a single shot. The mixed MMRV vaccine barely will increase the danger of a febrile seizure within the seven to 10 days after vaccination, in contrast with giving separate vaccines.
However this threat wants context. For each 2,300 youngsters who obtain a primary dose of MMRV, there is perhaps one further febrile seizure, in contrast with separate vaccines. There isn’t any further threat for the second dose.
Febrile seizures occur in round 2% of kids earlier than age 5—no matter vaccines. Throughout a febrile seizure, a baby could grow to be stiff, twitch or shake, and be unresponsive. These are scary to look at however often innocent, sometimes resolving inside a couple of minutes with out therapy.
This small threat have to be weighed in opposition to chickenpox’s appreciable harms. Although generally seen as a light childhood sickness, chickenpox causes important disruption.
A Bristol research discovered that even delicate instances cut back high quality of life, disrupting sleep and inflicting tiredness and ache. Extra severely, chickenpox can result in extreme problems together with bacterial pores and skin infections, pneumonia, mind irritation, sepsis, stroke and loss of life.
In England, there are round 4,500 hospital admissions a 12 months because of chickenpox—and this can be an underestimate, because it depends on chickenpox being recognized and recorded because the underlying trigger.
Folks with weakened immune methods face notably excessive dangers.
Chickenpox in being pregnant impacts round three in 1,000 pregnancies. Within the first trimester, there’s a uncommon however critical threat of a situation known as fetal varicella syndrome, which impacts the event of the fetus. Pregnant girls are at elevated threat of extreme pneumonia, and fetuses and newborns are additionally prone to extreme chickenpox an infection. Whereas uncommon, it may be deadly.
Shingles
The virus additionally creates long-term issues. After an infection, it lies dormant and may reactivate as painful shingles later in life.
Nations with chickenpox vaccination applications have seen dramatic enhancements. The US program has prevented 91 million instances of chickenpox, 238,000 hospitalizations and virtually 2,000 deaths.
Hospital admissions have fallen for all age teams in nations such because the US, Australia, Canada and Germany. Past well being advantages, vaccination saves day without work faculty and work—each greenback spent on chickenpox vaccination within the US saves US$1.70 (£1.26), making a web saving of US$23.4 billion over 25 years.
You may surprise why the UK hasn’t vaccinated sooner. There was concern that pure chickenpox virus circulating within the inhabitants helped enhance grownup immunity in opposition to shingles. Thirty years of US knowledge counsel this perception was unfounded.
Vaccinating youngsters has not been seen to extend shingles in older adults. We additionally now have efficient shingles vaccines for older individuals.
So why is the UK selecting the mixed MMRV strategy that the US is proscribing? The mixed vaccine works simply in addition to separate pictures and affords sensible benefits. Infants obtain fewer injections.
Surveys within the UK counsel round 85% of oldsters would settle for a chickenpox vaccine and will desire a mixed MMRV vaccine to a number of jabs. Fewer needles and appointments can encourage vaccine uptake. Whereas UK vaccine protection is excessive, delays can stack up with every extra appointment.
Vaccine uptake issues enormously. Vaccines shield not simply the kid who receives them, however everybody in the neighborhood by lowering illness circulation—referred to as “herd immunity.” That is key to eliminating ailments equivalent to measles, however solely works with excessive vaccination charges. The US adjustments prohibit parental alternative about utilizing the MMRV vaccine, and threat undermining the general public belief that profitable vaccination applications depend upon.
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Chickenpox: Why the UK has permitted the MMRV vaccine in under-fours however the US is making ready to limit it (2025, September 29)
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