As the rest of the world struggles to vaccinate adults in the face of a threat from a new coronavirus variant, China has embarked on an ambitious campaign that it says will give the country better protection against COVID-19: full inoculation of 160 million of its youngest citizens by the end of the year.

The campaign — powered in part with red flower stickers, balloons and boxes of toys for children who step up to become what nurses call "little inoculated warriors” — has gotten off to a fast start. In the first two weeks of the effort, which began in late October, 84 million boys and girls between the ages of 3 and 11, about half of the eligible population, received the first of two shots, according to the most recent government data.

By contrast, in the United States, 2.6 million children between ages 5 and 11, or about 10% of the eligible population, received one dose over roughly the same time period.