VOA慢速英语:新冠肺炎康复者是否会二次感染？

tracker – n. a device or online tool that shows where someone or something is or the state of something

immune system – n. the system of the body that fights infection and disease and that includes especially the white blood cells and antibodies and the organs that produce them

pathogen – n. medical : something (such as a type of bacteria or a virus) that causes disease

check – v. to inspect, examine, or look at appraisingly or appreciatively —usually used with out or over

specific – adj. relating to a particular person, situation, etc.

expose – v. to subject to risk from a harmful action or condition children exposed to measles

positive – adj. the result from a test that shows that a particular germ, condition, or substance is present

relapse – v. of an illness : to return or become worse after leaving or improving for a period of time

inconsistent – adj. not continuing to happen or develop in the same way