immune – n. of or relating to the body's immune system

response – n. reaction

old-fashioned – adj. out of date; older; opposite of modern

trial – n. a kind of testing and research that aims to show that vaccines work and are safe

cautious – adj. careful; watchful

pneumonia – n. medical a serious disease that affects the lungs and makes it difficult to breathe

symptom – n. a change in the body or mind which shows that a disease is present

respiratory – adj. medical of or relating to breathing or the organs of the body that are used in breathing

antibody – n. medical: a substance produced by the body to fight disease

delivery – n. the action of supplying or moving something

conversation – n. a talk involving two people or more people