Rate of positive PCR by feeding mode, place and type of delivery, and by children's age group.

*This means the child was still breastfeeding at the time of dried blood spot (DBS) collection for PCR.**This means the child was breastfed but stopped by the time of DBS collection. The timing when breastfeeding was stopped was not specified.* 此情形指在为聚合酶链式反应（Polymerase Chain Reaction，PCR）采集干血斑（Dried Blood Spot，DBS）样本时，该儿童仍处于母乳喂养状态。 * 此情形指该儿童曾接受母乳喂养，但在采集干血斑（DBS）样本时已停止哺乳，且未明确停止母乳喂养的具体时间。