Delaying Vaccines Increases Risks—with No Added Benefits

Concerns about vaccine safety have led up to 40 percent of parents in the U.S. to delay or refuse some vaccines for their children in hopes of avoiding rare reactions. Barriers to health care access can also cause immunization delays. But delaying some vaccines, in addition to leaving children unprotected from disease longer, can actually increase the risk of fever-related seizures, according to a new study.

The U.S. Centers for Disease Control and Prevention annually updates its recommended childhood immunization schedule, the only schedule endorsed by the American Academy of Pediatrics and other medical organizations. Following the CDC guidelines means children may get as many as five vaccines at one visit. But some parents space out vaccines, leading to delays in shots such as the first measles-mumps-rubella (MMR) dose, recommended when a child is between 12 and 15 months old.

The new study, published in the May 19 Pediatrics, found that administering the MMR shot or the less frequently used MMRV one (which includes the varicella, or chickenpox, vaccine) later, between 16 and 23 months, doubles the child’s risk of developing a fever-caused, or febrile, seizure as a reaction to the vaccine. The risk of a febrile seizure following the MMR is approximately one case in 3,000 doses for children aged 12 to 15 months but one case in 1,500 doses for children aged 16 to 23 months “This study adds to the evidence that the best way to prevent disease and minimize side effects from vaccines is to vaccinate on the recommended schedule,” says Simon Hambidge, lead author of the study and the director of general pediatrics at Denver Health. Otherwise, he says, an undervaccinated child is left at risk of infectious disease for a longer period. “Delaying also makes for increased visits to the doctor’s office,” he says, “along with the time and hassle and risk of exposure to other infectious diseases in the doctor’s office.” Hambidge’s previous research found that pediatric office visits might increase the risk of gastrointestinal illness (symptoms then potentially misinterpreted as a vaccine reaction).

Cited from Scientific American.