As it fights a pandemic, CDC wages a second battle to win back trust "We're following the science." The line rolls regularly off the tongues of top US health officials -- no one more so than US Centers for Disease Control and... Posted: May 22, 2021 9:51 AM Posted By: CNN "We're following the science." The line rolls regularly off the tongues of top US health officials -- no one more so than US Centers for Disease Control and Prevention Director Dr. Rochelle Walensky. Science dictated last week's guidance -- widely criticized as confusing -- advising fully vaccinated Americans that they could ditch the masks under most circumstances, Walensky said, citing studies showing the coronavirus vaccines not only provide better than 90% protection in real life, but also likely prevent vaccinated people from inadvertently infecting others.