With U.S. recommendations for COVID-19 vaccines in flux, a leading member of the CDC's COVID vaccine advisory group is reportedly jumping ship.

Lakshmi Panagiotakopoulos, M.D., a nearly 10-year CDC employee, served as a co-leader of the CDC’s Advisory Committee on Immunization Practices (ACIP) work group on COVID vaccines until resigning in a Tuesday email to colleagues, Reuters first reported.

"My career in public health and vaccinology started with a deep-seated desire to help the most vulnerable members of our population, and that is not something I am able to continue doing in this role,” Panagiotakopoulos wrote in the email, according to the news service.

The official specializes in pediatric infectious diseases and called the departure a “personal decision” in the message, according to Reuters.

Her decision comes amid a wave of uncertainty for COVID vaccines and the broader U.S. vaccination infrastructure.

Last week, HHS Secretary Robert F. Kennedy Jr. announced that COVID vaccines are no longer on the list of CDC-recommended vaccines for pregnant women and “healthy” children, citing a lack of "clinical data to support the repeat booster strategy in children."

The abrupt change was criticized for its apparent lack of expert backing, with Public Citizen Health Research Group Director Robert Steinbrook, M.D., explaining in a statement that the CDC’s immunization schedule must be developed by CDC scientists “through the well-established federal consultation process, not single-handedly by the HHS Secretary.”

Still, FDA Commissioner Marty Makary, M.D., stood beside Kennedy in the video announcement, agreeing that there’s “no evidence that healthy kids need [a COVID booster] today.”

Makary and Center for Biologics Evaluation and Research head Vinay Prasad, M.D., had recently unveiled a new FDA policy stance on COVID-19 vaccines in an article published in The New England Journal of Medicine. In the article, the FDA leaders laid out the need for “robust, gold-standard data” to support approvals for new COVID vaccines for those who are at a low risk for severe outcomes.

Since then, Moderna’s next-gen COVID shot mNEXSPIKE scored agency approval for use in all adults 65 and older, as well as in individuals ages 12 to 64 who have one or more underlying risk factors for severe COVID. Novavax’s COVID vaccine was previously cleared with those restrictions.

The CDC's website notes that COVID recommendations "have recently been updated for some populations." The agency plans an update to the site to "align with the updated immunization schedule."

Meanwhile, ACIP is set to meet later this month to deliberate on vaccine recommendations.