Youyou (呦呦) is from the Book of Songs (Shijing) — the cry of the deer eating wild herbs in the field. Tu Youyou (born 1930) is the Chinese pharmacologist who won the 2015 Nobel Prize in Physiology or Medicine for discovering artemisinin — the antimalarial drug derived from sweet wormwood (Artemisia annua) that has saved millions of lives.
Youyou does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
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In Pythagorean numerology the letters of Youyou reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.