The head of the Centers for Disease Control and Prevention is defending the decision to ease mask-wearing guidance for fully vaccinated people, stressing that increasing political pressure had nothing to do with the abrupt shift in guidelines.

CDC Director Rochelle Walensky told FOX News Sunday that she delivered the science as soon as it was available.

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To date more than 156 million Americans, or more than 47% of the population, have received at least one dose of COVID-19 vaccine, and more than 121 million are fully vaccinated.

Walensky cautioned that even with the new guidelines, it was still too early to declare victory, but added that she was cautiously optimistic about the pandemic.

LOOK: 50 images of winning moments from sports history

Sometimes images are the best way to honor the figures we've lost. When tragedy swiftly reminds us that sports are far from the most consequential thing in life, we can still look back on an athlete's winning moment that felt larger than life, remaining grateful for their sacrifice on the court and bringing joy to millions.

Read on to explore the full collection of 50 images Stacker compiled showcasing various iconic winning moments in sports history. Covering achievements from a multitude of sports, these images represent stunning personal achievements, team championships, and athletic perseverance.