Answer:

1. antibody

- any of a large number of proteins of high molecular weight that are produced normally by specialized B cells after stimulation by an antigen and act specifically against the antigen in an immune response, that are produced abnormally by some cancer cells, and that typically consist of four subunits including two heavy chains and two light chains

- any of a large number of proteins of high molecular weight that are produced normally by specialized B cells after stimulation by an antigen and act specifically against the antigen in an immune response, that are produced abnormally by some cancer cells, and that typically consist of four subunits including two heavy chains and two light chains— called also immunoglobulin

(source: Merriam Webster dictionary)

2. vaccine

- a preparation that is administered (as by injection) to stimulate the body's immune response against a specific infectious agent or disease.

(source: Merriam Webster dictionary)

3. facemask

-a mask or protective covering for the face or part of the face.

-a mask or protective covering for the face or part of the face.- a covering (as of polypropylene fiber or cotton fabric) for the mouth and nose that is worn especially to reduce the spread of infectious agents (such as viruses or bacteria).

(source: Merriam Webster dictionary)

4. social distancing

- the practice of maintaining a greater than usual physical distance from other people or of avoiding direct contact with people or objects in public places during the outbreak of a contagious disease in order to minimize exposure and reduce the transmission of infection.

(source: Merriam Webster dictionary)

5. distance learning

- distance learning, also called distance education, e-learning, and online learning, form of education in which the main elements include physical separation of teachers and students during instruction and the use of various technologies to facilitate student-teacher and student-student communication.

(source: https://www.britannica.com)