The review found that some guidance "used less direct language than available evidence supported," "needed to be updated to reflect the latest scientific evidence" and "presented the underlying science base for guidance inconsistently," according to the spokesperson.
Additionally, the review identified three documents that were not primarily authored by the CDC and yet were presented as CDC documents, according to the spokesperson. The agency has removed two of the documents from its website, and updated and replaced the third.
The review was ordered by President Joe Biden's CDC director, Dr. Rochelle Walensky, in response to concerns about some of the agency's guidance during the first year of the pandemic under the Trump administration.
"I am focused on moving CDC forward with science, transparency and clarity leading the way. It is imperative for the American people to trust CDC. If they don't, preventable illness and injury can occur -- and, tragically, lives can and will be lost," Walensky said in a statement to CNN.
"This agency and its critical health information cannot be vulnerable to undue influence, and this report helps outline our path to rebuilding confidence and ensuring the information that CDC shares with the American people is based on sound science that will keep us, our loved ones, and our communities healthy and safe."