CNN  — 

During the Covid-19 pandemic, there have been “concerning” declines in childhood vaccinations against other infectious diseases, Dr. Rochelle Walensky, director of the US Centers for Disease Control and Prevention, said during a White House briefing on Friday.

Walensky urged parents to make sure their children are up to date on their vaccines.

“On-time vaccination throughout childhood is essential because it helps to provide immunity before children are exposed to potentially life-threatening diseases. During the pandemic, we have seen substantial declines in pediatrician visits, and because of this, CDC orders for childhood vaccinations dropped by about 11 million doses – a substantial and historic decline,” Walensky said on Friday.

“As we work to get our children back to school, we certainly do not want to encounter other preventable infectious outbreaks, such as measles and mumps. When planning for your child’s safe return to childcare programs or school, please check with your child’s doctor to make sure that they are up to date on their vaccines,” Walensky said. “If they did fall behind, they can get caught up by following CDC’s catch-up immunizations schedule, available on the CDC website.”

The CDC recommends that children get 14 different vaccinations protecting against 19 different pathogens. Timing is important for many of the vaccines to create the strongest immunity.

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Signs first emerged around in the spring of last year that childhood vaccinations have plunged since the Covid-19 pandemic began. For instance, one study published in May by the CDC found that the number of childhood vaccines administered in Michigan dropped by as much as 22% amid the coronavirus pandemic.

Those findings published less than two weeks after another report from the CDC showed childhood vaccinations plunged across the United States since the pandemic began.

CNN’s Maggie Fox and Arman Azad contributed to this report.