None of the COVID-19 vaccines currently in development in the United States use the live virus that causes COVID-19.
Vaccination can cause short-term discomfort (such as headache, muscle pains, fatigue, chills, fever, and pain at injection site) in a percentage of the people who receive them. This is the effect of your body developing immunity. When you receive the second dose of the vaccine, the discomfort can be more pronounced. This is a normal reaction, so be prepared.
Typically takes a few weeks for the body to build immunity after vaccination.
It is possible a person could be infected with the virus that causes COVID-19 just before or just after vaccination and get sick. This is because the vaccine has not had enough time to provide protection.
Vaccines currently in clinical trials in the United States will not cause you to test positive on viral tests, which are used to see if you have a current infection.
If your body develops an immune response, which is the goal of vaccination, there is a possibility you may test positive on some antibody tests.
Due to the severe health risks associated with COVID-19 and the fact that re-infection with COVID-19 is possible, people may be advised to get a COVID-19 vaccine even if they have been sick with COVID-19 before.
The mRNA (messenger ribonucleic acid) from a COVID-19 vaccine never enter the nucleus of the cell, which is where our DNA are kept. This means the mRNA does not affect or interact with our DNA in any way. Instead, COVID-19 vaccines that use mRNA work with the body’s natural defenses to safely develop protection (immunity) to disease.
COVID-19 vaccines help our bodies develop immunity to the virus that causes COVID-19 without us having to get the illness.
All but one of the COVID-19 vaccines that are currently in Phase 3 clinical trials in the United States use two shots. The first shot starts building protection. A second shot a few weeks later is needed to get the most protection the vaccine has to offer. One vaccine in Phase 3 clinical trials only needs one shot.
HUMAN IMMUNUE SYSTEM
When COVID-19 virus, invade our bodies, they attack and multiply. This invasion, called an infection, is what causes illness. Our immune system uses several tools to fight infection. Blood contains red cells, which carry oxygen to tissues and organs, and white or immune cells, which fight infection. Different types of white blood cells fight infection in different ways:
Macrophages are white blood cells that swallow up and digest germs and dead or dying cells. The macrophages leave behind parts of the invading germs called antigens. The body identifies antigens as dangerous and stimulates antibodies to attack them.
B-lymphocytes are defensive white blood cells. They produce antibodies that attack the pieces of the virus left behind by the macrophages.
T-lymphocytes are another type of defensive white blood cell. They attack cells in the body that have already been infected.
The first time a person is infected with the virus that causes COVID-19, it can take several days or weeks for their body to make and use all the germ-fighting tools needed to get over the infection. After the infection, the person’s immune system remembers what it learned about how to protect the body against that disease.
The body keeps a few T-lymphocytes, called memory cells, that go into action quickly if the body encounters the same virus again. When the familiar antigens are detected, B-lymphocytes produce antibodies to attack them. Experts are still learning how long these memory cells protect a person against the virus that causes COVID-19.
HOW COVID-19 VACCINES WORK
COVID-19 vaccines help our bodies develop immunity to the virus that causes COVID-19 without us having to get the illness. Different types of vaccines work in different ways to offer protection, but with all types of vaccines, the body is left with a supply of “memory” T-lymphocytes as well as B-lymphocytes that will remember how to fight that virus in the future.
It typically takes a few weeks for the body to produce T-lymphocytes and B-lymphocytes after vaccination. Therefore, it is possible that a person could be infected with the virus that causes COVID-19 just before or just after vaccination and then get sick because the vaccine did not have enough time to provide protection.
Currently, there are three main types of COVID-19 vaccines that are or soon will be undergoing large-scale (Phase 3) clinical trials in the United States. Below is a description of how each type of vaccine prompts our bodies to recognize and protect us from the virus that causes COVID-19. None of these vaccines can give you COVID-19.
At this time, experts do not know how long someone is protected from getting sick again after recovering from COVID-19. The immunity someone gains from having an infection, called natural immunity, varies from person to person. Some early evidence suggests natural immunity may not last very long.