Frequently Asked Questions on the COVID-19 Vaccine

What are the benefits of getting vaccinated?

The COVID-19 vaccines produce protection against the disease, as a result of developing an immune response to the SARS-Cov-2 virus. Developing immunity through vaccination means there is a reduced risk of developing the illness and its consequences. This immunity helps you fight the virus if exposed. Getting vaccinated may also protect people around you, because if you are protected from getting infected and from disease, you are less likely to infect someone else. This is particularly important to protect people at increased risk for severe illness from COVID-19, such as healthcare providers, older or elderly adults, and people with other medical conditions.

Are COVID-19 vaccines safe and effective?

The COVID-19 vaccines have undergone the most scrutinous safety monitoring in U.S. history. They are approved by the Food and Drug Administration’s (FDA) scientific standards for safety, effectiveness, and manufacturing quality. So far, hundreds of millions of people in the United States have received COVID-19 vaccines under the most intense safety monitoring in U.S. history.

Will COVID-19 vaccines provide long-term protection?

Pfizer, Moderna, and Johnson & Johnson have been monitoring immunity in people who were given their vaccines in the initial clinical trials. Both companies have reported strong overall efficacy at the six-month mark. After six months, research has shown the efficacy of these vaccines to begin to decline, which is why a booster is recommended to maintain a maximum immune response.

How do COVID-19 vaccines work?

These vaccines are all designed to teach the body’s immune system to safely recognize and block the virus that causes COVID-19.

What is the difference between how the Johnson & Johnson vaccine works and how the Pfizer and Moderna vaccines work?

The Moderna and Pfizer vaccines use mRNA technology, and the Johnson & Johnson vaccine uses the more traditional virus-based technology.

mRNA is essentially a little piece of code that the vaccine delivers to your cells. The code serves as an instruction manual for your immune system, teaching it to recognize the virus that causes COVID-19 and attack it, should it encounter the real thing.

Instead of using mRNA, the Johnson & Johnson vaccine uses a disabled adenovirus to deliver the instructions. This adenovirus is not related to the coronavirus. It is a completely different virus. Although it can deliver the instructions on how to defeat the coronavirus, it cannot replicate in your body and will not give you a viral infection. 

Can we stop taking precautions after being vaccinated?

Vaccination protects you from getting seriously ill and dying from COVID-19. For the first fourteen days after getting a vaccination, you do not have significant levels of protection. Then it increases gradually. For a single dose vaccine, immunity will generally occur two weeks after vaccination. For two-dose vaccines, both doses are needed to achieve the highest level of immunity possible.

Maintaining preventative measures is important especially in communities where SARS CoV-2 circulation is significant. To help keep you and others safe, and while efforts continue to reduce viral transmission and expand vaccine coverage, you should continue to maintain at least 6 feet distance from others, cover a cough or sneeze in your elbow, clean your hands frequently and wear a mask, particularly in enclosed, crowded or poorly ventilated spaces. Always follow guidance from local authorities based on the situation and risk where you live.

Can the COVID-19 vaccine cause a positive test result for the disease, such as for a PCR or antigen test?

The COVID-19 vaccine will not cause a positive test result for a COVID-19 PCR or antigen laboratory test. This is because the tests check for active disease and not whether an individual is immune or not. However, because the COVID-19 vaccine prompts an immune response, it may be possible to test positive in an antibody (serology) test that measures COVID-19 immunity in an individual.

Should I be vaccinated if I have had COVID-19?

Even if you have already had COVID-19, you should be vaccinated when it is offered to you. The protection that someone gains from having COVID-19 will vary greatly from person to person. The immunity people get from being vaccinated after having a natural infection is consistently very strong. Getting vaccinated even if you have had COVID-19 means you are more likely to be protected for longer.

Do the vaccines protect against variants?

A growing body of data suggests that most vaccines stimulate enough immunity to retain substantial efficacy against most variants, especially for severe disease, hospitalization, and death.

The reason vaccines substantially retain protection against disease is likely related to the broad immune response they induce, which means that virus changes or mutations are unlikely to make vaccines completely ineffective. If any of these vaccines become less effective against one or more variants, it will likely be possible to change the composition of the vaccines to protect against these variants, however this will take time and additional data to fully evaluate.

Does the vaccine cause different side effects in men and women? Does age have an impact?

The effect of the COVID-19 vaccine varies from person to person, like it does for most vaccines. As more people get vaccinated, we may be able to determine patterns. This information continues to be collected and will be shared, but for now, we cannot anticipate who may have side effects.

Does having side effects mean that the vaccine is working? What does having no side effects mean?

The vaccine stimulates your immune system to protect you from the virus. This process can sometimes cause side effects like fever, chills, or headache, but not everyone experiences this. The presence or magnitude of the reaction you may have after vaccination does not predict or reflect your immune response to the vaccine. You do not have to have side effects in order to be protected. 

What is the difference between the immunity you develop from getting COVID-19 and immunity from getting a COVID-19 vaccine?

We are still learning about how long immunity to COVID-19 lasts from natural infection, and from vaccination. We are now starting to see evidence that the immunity you get after having COVID-19 can be strong. However, the type of immunity that’s developed after infection varies from person to person, making it less predictable than immunity after vaccination.

What we do know is that COVID-19 is a life-threatening disease that can have long-term consequences. It is much safer to get vaccinated than it is to risk getting COVID-19.

What is the difference between the immunity you develop from getting COVID-19 and immunity from getting a COVID-19 vaccine?

For individuals who received a Pfizer-BioNTech or Moderna COVID-19 vaccine, the following groups are eligible for a booster shot at 6 months or more after their initial series:

·        65 years and older

·        Age 18+ who live in long-term care settings

·        Age 18+ who have underlying medical conditions

·        Age 18+ who work or live in high-risk settings

For the nearly 15 million people who got the Johnson & Johnson COVID-19 vaccine, booster shots are also recommended for those who are 18 and older and who were vaccinated two or more months ago.

There are now booster recommendations for all three available COVID-19 vaccines in the United States. Eligible individuals may choose which vaccine they receive as a booster dose. Some people may have a preference for the vaccine type that they originally received, and others may prefer to get a different booster. CDC’s recommendations now allow for this type of mix and match dosing for booster shots.