CDC panel proposes major shift in three-shot vaccine protocol

New Recommendation for Childhood Vaccines

A significant decision has been made by a panel of experts, leading to a change in the recommended vaccination schedule for young children. The panel, which is part of an advisory committee led by Robert F. Kennedy Jr., has voted to revise the recommendation for major childhood vaccines. This decision was made on Thursday, with a vote of 8-3, and one member abstaining. The panel now suggests that children aged four and under should no longer receive the combined measles-mumps-rubella-varicella (MMRV) vaccine. Instead, they recommend that these children be given the measles, mumps, and rubella (MMR) shot along with the varicella (chickenpox) vaccine separately.

This shift does not mean that either vaccine is being withdrawn from use. Both are still considered essential for preventing serious and potentially fatal diseases. However, it may create challenges for parents who wish to obtain the combined shot for their young children. The MMRV vaccine has been associated with a slightly higher risk of febrile seizures compared to administering the two shots separately during the same doctor’s visit.

Currently, the Centers for Disease Control and Prevention (CDC) recommends that the first dose of MMR and varicella vaccines should be administered separately unless a parent specifically requests the combined version. This new recommendation comes from Kennedy's newly formed 12-member Advisory Committee on Immunization Practices (ACIP), which includes several individuals known for their skepticism towards vaccines.

Kennedy, a long-time critic of vaccines, has argued that re-examining the childhood vaccine schedule is necessary to restore public trust in health agencies. However, this decision has faced criticism from various quarters. Merck, the manufacturer of the combined shot, expressed strong disapproval, stating that the decision was made without any new scientific data and contradicted years of evidence supporting the current immunization schedule.

Experts have also raised concerns about the potential impact of this change. Dr. Aaron Milstone, a pediatric infection control chief at Johns Hopkins Children’s Center, warned that the change could reduce access to protection against diseases that once affected tens of thousands annually.

The recommendation still needs approval from the acting CDC director, Jim O’Neill, before it becomes official guidance. O’Neill took over from Dr. Susan Monarez, who had claimed she was fired for upholding scientific integrity. The decision was made following a day-long meeting of the committee at the CDC headquarters in Atlanta, Georgia. The committee will reconvene today and is expected to discuss guidance on the hepatitis B vaccine, which is administered in three doses at birth, one to two months, and six to 18 months of age.

The MMRV vaccine was first approved in the United States in 2005. It combines the MMR shot, which is given in two doses at 12 to 15 months and 4 to 6 years of age, with the chickenpox shot, which is also administered in two doses at the same ages. However, data showed a higher risk of adverse reactions when using the combined shot as a first dose, leading the CDC to advise against its use in children under four years old unless parents requested it.

According to the agency, when the first doses of the MMR and varicella shots are given separately on the same visit, about 15 out of every 100 children develop a fever, and four out of every 10,000 suffer a febrile seizure. When the shots are given as a combined first dose, the risk of a fever increases to 22 out of every 100 children, while the risk of a febrile seizure doubles to eight out of every 10,000 children. Doctors suggest this may occur because the body reacts strongly to all four viruses being vaccinated against simultaneously.

Febrile seizures can appear alarming but typically last only a few minutes and rarely result in long-term complications. Doctors have not found a higher risk of febrile seizures when the MMRV vaccine is given as a second dose, likely because the immune system has already been exposed to the viruses through the first shot. Since the second dose is given after age four, the new recommendation would not affect whether the MMRV vaccine can be used as a second dose.

All vaccines, whether administered separately or combined, offer the same level of protection against diseases that once caused widespread illness. Before the introduction of vaccines, millions of people were infected with measles each year in the US, with thousands hospitalized and hundreds dying from the disease. Chickenpox used to infect millions of children annually, leading to thousands of hospitalizations and dozens of deaths.

The US has maintained a measles elimination status since 2000, but there have been 1,491 cases reported so far this year, the highest number since the disease was declared eliminated. Chickenpox affects an estimated 100,000 to 150,000 people annually in the US.

If approved, the recommendation would align US guidelines with countries like Australia and France, which advise giving the MMR and varicella vaccines separately. Other countries such as Canada and Italy allow parents to choose between the MMRV vaccine as a first dose or the separate MMR and varicella shots. In contrast, the UK plans to start offering the combined MMRV shot as a first dose from January 2026.