COVID is a serious disease（疾病）which affects your ability to breathe. It is caused by a new type of coronavirus（冠状病毒）that was first identified in 2019.
COVID-19 (coronavirus disease 2019)
is a severe急性的 viral 病毒的infection感染 of the lungs 肺部characterized by fever发烧, a dry cough干咳, breathing difficulties呼吸困难 and fatigue疲劳.
A virus 病毒 is a kind of germ 细菌/病菌that can cause disease.
If a video, image, or story goes viral, it spreads quickly and widely on the internet through social media and email.
The sun's corona 日冕，日华; 冠状物 is its outer atmosphere.
A crown 王冠;皇冠;冕;(戴在头上的)冠状物is a circular ornament, usually made of gold and jewels, which a king or queen wears on their head at official ceremonies.
If there is an epidemic 流行病of a particular disease somewhere, it affects a very large number of people there and spreads 传播 quickly to other areas.
A pandemic疾病的大流行 is an occurrence of a disease that affects many people over a very wide area.
A plague瘟疫 is a very infectious 传染性的disease that spreads quickly and kills large numbers of people.
To infect 传染;侵染;感染 people, animals, or plants means to cause them to have a disease or illness.
Disinfectant消毒剂 is a substance that kills germs. It is used, for example, for cleaning kitchens and bathrooms.
Contagion is the spreading of a particular disease by someone touching another person who is already affected by the disease.
——any disease easily transmitted by contact
A disease that is contagious（病）接触传染的 can be caught by touching people or things that are infected with it.
A vaccine 疫苗 is a substance containing a harmless form of the germs that cause a particular disease. It is given to people, usually by injection 注射, to prevent them getting that disease.
If a person or animal is vaccinated 打疫苗, they are given a vaccine, usually by injection, to prevent them from getting a disease.