Study finds earlier is better for first dose of measles vaccine

Children receiving measles-containing vaccines at 12 to 15 months of age have less risk of fever and seizures than children who receive the vaccines later, according to a recent study in JAMA Pediatrics.

Researchers with Kaiser Permanente used data from the Vaccine Safety Datalink to evaluate the potential modifying effect of age on the risk of fever and seizures following immunization. The researchers found the relative risk of fever and seizures during the seven to 10 day risk interval was significantly greater among children 16 to 23 months of age than among children in the younger age group.

"We found that the magnitude of increased risk of fever and seizures following immunization with measles-containing vaccines during the second year of life depends on age," Ali Rowhani-Rahbar, the lead author of the study, said. "While measles-containing vaccines administered at 12-15 months of age are associated with a small risk of fever and seizures following immunization, delayed administration at 16-23 months of age results in a greater risk of those adverse events."

The CDC recommends a two-dose series of measles-containing vaccines, with the first dose administered between 12 to 15 months. Most children get their first dose between the ages of 12 and 23 months with approximately 85 percent of children receiving it by 19 months of age.

"Kaiser Permanente's guidelines for measles-containing vaccines are in line with the CDC's recommendations," Matthew Daley, a senior investigator at Kaiser Permanente Colorado's Institute for Health Research, said. "This study's findings reinforce for parents that these vaccines are safer when children receive them at 12 to 15 months of age."

While febrile seizures are the most common neuralgic adverse event following measles-containing vaccines, the risk is less than one febrile seizure per 1,000 injections.