A group of experts advising the Centers for Disease Control and Prevention (CDC) recently voted to suggest that young children should not receive Merck & Co.’s combined measles, mumps, rubella, and chickenpox (MMRV) vaccine for their first dose. Instead, they recommend giving the chickenpox vaccine separately from the MMR vaccine in children age 4 and younger. Currently, doctors can choose between giving the combined MMRV vaccine or two separate shots. The committee voted 8-3, with one abstention, to make this change. The CDC director will now review the recommendation. Acting CDC director Jim O’Neill is expected to decide on the new guidelines after the recent removal of former head Susan Monarez. The change is based on data showing that the combined vaccine causes about twice as many fever-related seizures in young children compared to giving the shots separately. However, since the CDC already warned about this risk in 2008 and 2009, only about 15% of children in this age group currently receive the combined vaccine. Some committee members, like Cody Meissner from Dartmouth College, questioned whether the change was necessary, arguing that the current guidelines are already clear. Others supported the combined vaccine because it helps parents stick to the recommended vaccination schedule, preventing disease outbreaks. Changing the guidelines could also limit parents’ choices, as programs like the Vaccines for Children (VFC) may no longer cover the MMRV vaccine. However, insurers have agreed to cover any recommended vaccine through the end of 2026. On Thursday, the committee voted 8-1, with three abstentions, to keep the old guidelines for the VFC program, which includes the combined MMRV shot. This caused confusion, as some members wondered if this meant different rules depending on how a child’s vaccine was paid for. Meissner abstained from the vote. On Friday, the committee met again and re-voted, this time with 9 members in favor of adopting the new guidelines for the VFC program and 3 abstentions. Before the re-vote, Jason Goldman from the American College of Physicians criticized the committee’s handling of the issue, questioning whether the conflicting votes showed a lack of strong evidence for the change. The discussion focused heavily on the vaccine’s safety. Vicky Pebsworth, from the National Vaccine Information Center, argued that reducing fever-related seizures could benefit public health, as some studies suggest these seizures might be linked to conditions like ADHD and epilepsy. Meissner disagreed, pointing out that fever-related seizures are common and usually not harmful. The debate over the MMR vaccine schedule has been influenced by Health and Human Services Secretary Robert F. Kennedy, a known vaccine skeptic, who recently replaced all members of the advisory committee and fired the former CDC director, Susan Monarez. The MMR vaccine has long been a target of anti-vaccine activists, following the now-discredited claims by British doctor Andrew Wakefield linking the vaccine to autism. Kennedy’s department is expected to release a report on autism this month. The committee also planned to vote on changes to hepatitis B vaccination recommendations but delayed the decision indefinitely.