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January 7, 2022

How do the COVID-19 vaccines protect me?

The answers on this site were developed with and vetted by the CDC

COVID-19 vaccines are a critical tool to bring the pandemic under control. The risk of severe disease and death are all much lower for people who are vaccinated, compared to unvaccinated people. All authorized COVID-19 vaccines provide strong protection against serious illness and hospitalization due to COVID-19.

When we get a vaccine, it activates our immune response. This helps our bodies learn to fight off the virus without the danger of an actual infection. If we are exposed to the virus in the future, our immune system “remembers” how to fight it.

The Moderna and Pfizer-BioNTech vaccines use messenger RNA, or mRNA. mRNA vaccines do not contain a live virus. They give our bodies “instructions” for how to make and fight the spike-shaped proteins that will protect against a COVID-19 infection. While these vaccines use new technology, researchers have been studying them for decades.

Johnson & Johnson’s Janssen vaccine is a viral vector vaccine and does not contain a live virus either. It uses a harmless adenovirus to create a spike protein that the immune system responds to, creating antibodies to protect against COVID-19.

None of these vaccines can give you COVID-19.

It takes time for your body to build immunity after vaccination, so you won’t have full protection until 2 weeks after your most recent dose.

Dr Angelica Kottkamp Video
How vaccines work (vaccines.gov)

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What are the differences between the vaccines?

COVID-19 vaccines provide strong protection from serious illness and hospitalization. Getting vaccinated and following CDC’s recommendations to take care of yourself and others is the best way to protect against COVID-19. CDC and other health experts are currently recommending mRNA vaccines (Pfizer-BioNTech and Moderna) as the preferred vaccines to protect against new variants.

The Pfizer-BioNTech vaccine (Comirnaty) is authorized for people ages 5 and older. It’s a messenger RNA, or mRNA, vaccine and includes two shots spaced 21 days apart. This vaccine was fully approved by the FDA for ages 16 and older in August 2021. It’s also available for ages 5 to 15 under emergency use authorization (and is being given in smaller doses to children age 5 to 11).

The Moderna vaccine is authorized for people 18 years and over. It’s also an mRNA vaccine and includes two shots spaced 28 days apart. Clinical trials showed the Moderna vaccine also provides strong protection against serious illness.

For people who are unable or unwilling to receive an mRNA vaccine, the Johnson & Johnson Janssen vaccine is still authorized and available for people 18 years and over. It’s a viral vector vaccine and only requires one shot.

Different vaccines work (CDC)
If you’re ready to get vaccinated, get up-to-date information on locations near you.
Do the vaccines protect against the variants?

Staying up to date with COVID vaccines provides strong protection against severe disease and death when it comes to new variants. This includes booster shots at the appropriate time. Vaccines also reduce a person’s risk of getting the virus. But no vaccine is 100% effective and some fully vaccinated people will become infected and experience illness. This is called a breakthrough infection. When one happens, the vaccines still provide strong protection against serious illness and death.

The Delta variant and Omicron variant are extremely contagious — more than twice as contagious as the original virus. People who have not been fully vaccinated against COVID-19 are most at risk and more likely to transmit the virus to others.

What You Need to Know about Variants (CDC)
What should I know about breakthrough infections?

COVID-19 vaccines are an effective tool to bring the pandemic under control. No vaccines are 100% able to prevent illness. Fortunately, the risk of serious illness, hospitalization, and death are all much lower if you’re vaccinated.

Recent data shows that vaccine effectiveness decreases over time. New variants are also even more infectious than the original virus. Because of this, CDC recommends that everyone age 12+ receive a booster shot at the appropriate time.

The Possibility of COVID-19 after Vaccination: Breakthrough Infections (CDC)
What are mRNA vaccines and how do they work?

Many vaccines put a weakened or inactivated germ into your body to build immunity. But messenger RNA (mRNA) vaccines teach your cells how to make a protein that will trigger an immune response inside your body. This produces antibodies that protect you if the real virus were to enter your body. Since mRNA vaccines don't use an actual virus, they can be safely produced in large quantities faster than other vaccines.

The Moderna and Pfizer-BioNTech vaccines use mRNA. While these vaccines use new technology, researchers have been working with mRNA vaccines for decades. mRNA vaccines were studied before for flu, Zika, rabies, and cytomegalovirus (CMV).

mRNA never enters the nucleus of the cell where DNA is located, so it cannot change your genes. Our cells break down mRNA and get rid of it within a few days after vaccination.

Understanding mRNA COVID-19 Vaccines (CDC)

Looking for a vaccine? Visit the Vaccine Finder to get up-to-date information on locations near you.


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