Part I: The Measles, Mumps, Rubella and Varicella (MMRV) Vaccine
The Issue – Children are recommended to receive a two-shot series of measles, mumps, rubella (German measles), and varicella (chickenpox) vaccines with the first dose at 12 – 15 months of age and the second dose between ages 4 – 6 years. There are two ways to accomplish this – give an MMR (measles/mumps/rubella) vaccine in one arm or thigh and a varicella vaccine in the other or give a single vaccine that contains all the vaccines together – MMRV.
The first issue considered at this week’s Advisory Committee on Immunization Practices (ACIP) for the CDC was whether to change a long-standing (2010) prior recommendation that children may receive either the two separate vaccines (referred to as MMR + V) or the single-dose, quadrivalent vaccine (MMRV) for either of the two-dose series, however, the MMR + V is preferred for children ages 12 – 47 months getting their first dose, while the MMRV is preferred for the second dose after age 4 years of age.
Why is there a preference for MMR + V for children under age 4 and a different preference for MMRV after age 4?
The immunogenicity of either approach is equivalent (immunogenicity refers to the effectiveness and magnitude of the immune response following vaccination).
Some young children are prone to brief, generalized seizures when they experience high fevers, whether from infection or vaccination. These are very distressing to parents and caregivers, but medically of little consequence or concern. By five years of age, 2 – 4 percent of all children will have had one or more febrile seizures. The most common age for febrile seizures is between ages 14 and 18 months. They are more common in children who have a family history of febrile seizures. Febrile seizures are rare after age 5 unless the child has structural brain disease.
When MMR + V are administered at the same visit, but in different extremities, in the children ages 12 – 23 months, about 14.9 percent of children will develop fever of more than 102 degrees F. When MMRV is administered in this age group, 21.5 percent of children will develop fever of that degree. Most of these children will be fine, but febrile seizures will occur in about 4 in 10,000 of the children who receive MMRV, about twice as often as in children who receive MMR + V.
Currently, about 85 percent of parents getting their children vaccinated opt for their young children to receive the MMR + V. However, about 15 percent of parents opt for the MMRV due to the fact that it decreases the number of injections their child has to get at the visit.
Older children are not generally at risk for febrile seizures, and thus MMRV is preferred because getting one shot instead of two increases vaccine compliance and vaccine coverage rates.
Why is the vaccine recommendation being revisited?
That was the key question that went unanswered, even though it was raised by at least a couple members of the committee, and cautioned against by several liaison groups of medical professionals.
No one suggested that there was new data that showed any concerns over this same data that has been reviewed in the past and for which the current recommendation was based.
What was the recommendation put before the committee by the chair to be voted upon?
The change would be rather than recommending both vaccine options with a preference for MMR + V in those children under age 4 and MMRV in those children over age 4, the new recommendation, if voted in favor by a majority of the ACIP members, would recommend only MMR + V for those children under age 4.
What were the arguments against the recommendation?
- As one committee member put it, why are we not trusting parents to make this decision? Why are we taking this option away from them, especially when 85 percent of parents vaccinating their children are going along with the preference?
- Changing the recommendation when there is no new evidence of compelling reason to do so will lead to provider confusion and confusion on the part of parents, and potentially erode trust further.
- The consequence of the change would be that the Vaccines for Children Program (which pays for vaccines for a little over half of all children in the U.S.) would no longer pay for the MMRV vaccine in the under 4 years old age category, nor would Medicaid. Further private insurance companies would no longer be required to pay for the vaccine.
What was the vote?
8 – 3 in favor, with one abstention.
What is my take?
I would have voted against the new recommendation. There was no new data, no new concerns, and no reason offered as to why a change was needed. Changes to the childhood vaccine schedule are disruptive and require a lot of communication and explanation to a massive health infrastructure across the country. When those changes are needed, they should be made. However, tinkering with the schedule, especially when the lack of expertise on the committee was pretty apparent, and multiple liaison organizations expressed concern about the lack of input from practicing pediatricians, can very easily lead to confusion, and in this case, it will result in an option being taken away from parents. As a life-time Republican, I believe in medical freedom and that government shouldn’t insert itself in medical decisions other when necessary. This was not necessary. No one indicated that there was a new or a continuing problem that needed to be addressed. Some members tried to create new issues by raising questions about long-term neurological consequences from febrile seizures, even though the few present with the necessary expertise indicated that febrile seizures are common, self-limited, very familiar to pediatricians, and that in the decades that we have been following children with these, we have never identified long-term sequelae.
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