COVID-19Common question

Are the Pfizer and Moderna COVID-19 vaccines interchangeable?

COVID-19 vaccines are not interchangeable. If you received a Pfizer-BioNTech or Moderna COVID-19 vaccine, you should get the same product for your second shot. You should get your second shot even if you have side effects after the first shot, unless a vaccination provider or your doctor tells you not to get it.

How many shots do I need with the Pfizer or Moderna COVID-19 vaccine?

If you receive a Pfizer-BioNTech or Moderna COVID-19 vaccine, you will need 2 shots to get the most protection.

Are the Moderna or Pfizer COVID-19 booster shots the same as the first?

If you got Moderna or Pfizer for your first dose: Moderna's booster dose will be half of its original dosing, while Pfizer's booster shot is the same as the initial doses.

How long after Pfizer COVID-19 vaccine booster is it effective?

The authors explain: “In this study, we estimated effectiveness starting from day 7 after the third dose, which is similar to the period used to define full vaccination after the second dose. Our choice is supported by high concentrations of antibodies in individuals 7 days after administration of the third dose.”

What happens if you don't take the second shot of the COVID-19 vaccine?

Put simply: Not receiving the second vaccine increases your risk of contracting COVID-19.

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How many doses of COVID-19 vaccine will I need to get?

The number of doses needed depends on which vaccine you receive. To get the most protection:

• Two Pfizer-BioNTech vaccine doses should be given 3 weeks (21 days) apart.
• Two Moderna vaccine doses should be given 1 month (28 days) apart.
• Johnson & Johnsons Jansen (J&J/Janssen) COVID-19 vaccine requires only one dose.

If you receive a vaccine that requires two doses, you should get your second shot as close to the recommended interval as possible. However, your second dose may be given up to 6 weeks (42 days) after the first dose, if necessary.. You should not get the second dose earlier than the recommended interval.

What happens if you get COVID-19 between first and second shots?

It's possible to become infected with COVID-19 between the first and second shots of the Pfizer and Moderna vaccines — and immediately following the second shot of these vaccines. If you do catch COVID-19 between the two vaccine doses, you should make sure to get the second shot once you're feeling better.

How long after Pfizer COVID-19 vaccine booster is it effective?

The authors explain: “In this study, we estimated effectiveness starting from day 7 after the third dose, which is similar to the period used to define full vaccination after the second dose. Our choice is supported by high concentrations of antibodies in individuals 7 days after administration of the third dose.”

How long will it take to build immunity after getting the COVID-19 vaccine?

It takes time for your body to build protection after any vaccination. People are considered fully vaccinated two weeks after their second shot of the Pfizer-BioNtech or Moderna COVID-19 vaccine, or two weeks after the single-dose J&J/Janssen COVID-19 vaccine.

Do COVID-19 vaccine boosters work?

Results from Israel indicate that a booster dose greatly lowers the risk of severe illness. Boosters also prevent infection. This reduces the spread of SARS-CoV-2 among vaccinated and unvaccinated individuals. It isn't yet clear how long protection from boosters will last, but the world can't wait to find out.

Are the Moderna or Pfizer COVID-19 booster shots the same as the first?

If you got Moderna or Pfizer for your first dose: Moderna's booster dose will be half of its original dosing, while Pfizer's booster shot is the same as the initial doses.

Is it safe to take a different COVID-19 booster shot?

The study found that boosting with a different vaccine is safe, and that boosters increased antibody levels no matter the combination.

Can I mix and match COVID-19 booster vaccines?

Boosters are now available for the three COVID-19 vaccines, made by Pfizer-BioNTech, Moderna and Johnson & Johnson. And the Centers for Disease Control and Prevention (CDC) has given the green light for safely mixing and matching the shots.

Do you need two Pfizer-BioNTech and Moderna COVID-19 vaccines?

If you received a Pfizer-BioNTech or Moderna COVID-19 vaccine, you should get the same product for your second shot. You should get your second shot even if you have side effects after the first shot, unless a vaccination provider or your doctor tells you not to get it.

What is the recommended interval between doses of the Pfizer-BioNTech and Moderna COVID-19 vaccines?

The recommended interval between doses is 21 days for Pfizer-BioNTech and 28 days for Moderna; however, up to 42 days between doses is permissible when a delay is unavoidable.

Are the Moderna or Pfizer COVID-19 booster shots the same as the first?

If you got Moderna or Pfizer for your first dose: Moderna's booster dose will be half of its original dosing, while Pfizer's booster shot is the same as the initial doses.

How long after Pfizer COVID-19 vaccine booster is it effective?

The authors explain: “In this study, we estimated effectiveness starting from day 7 after the third dose, which is similar to the period used to define full vaccination after the second dose. Our choice is supported by high concentrations of antibodies in individuals 7 days after administration of the third dose.”

Can you still get COVID-19 after booster vaccine?

COVID-19 is still a risk. Getting a booster shot doesn't guarantee you won't be infected with the coronavirus. But it can help your immune system build protection against severe disease or hospitalization -- including from the delta variant.

Can you still spread COVID-19 if you have the vaccine?

Vaccinated People Can Transmit the Coronavirus, but It's Still More Likely If You're Unvaccinated. COVID-19 vaccines continue to protect against severe illness but do not entirely block transmission. Fully vaccinated people are also less likely to contract the coronavirus than unvaccinated people.

How long after Pfizer COVID-19 vaccine booster is it effective?

The authors explain: “In this study, we estimated effectiveness starting from day 7 after the third dose, which is similar to the period used to define full vaccination after the second dose. Our choice is supported by high concentrations of antibodies in individuals 7 days after administration of the third dose.”

How does the COVID-19 booster shot work?

A COVID booster shot is an additional dose of a vaccine given after the protection provided by the original shot(s) has begun to decrease over time. Typically, you would get a booster after the immunity from the initial dose(s) naturally starts to wane.

How long do COVID-19 booster side effects last?

They're very similar to what happens after the second dose, which is that you do tend to get pain at the injection site, usually just lasts a few days, and usually it's not severe. And then you can get systemic side effects such as fever, fatigue, headache, and again, that usually goes away after a day or two.

How soon after exposure should I get tested for COVID-19 if vaccinated?

Get tested 3-5 days after their first exposure. A person with COVID-19 is considered infectious starting 2 days before they develop symptoms, or 2 days before the date of their positive test if they do not have symptoms.

What should be done if someone has a positive antigen test while being fully vaccinated against COVID-19?

In healthcare settings, infection prevention and control practices for caring for a person with COVID-19 should be followed until their isolation is discontinued. However, if the person who has received a positive antigen test result is fully vaccinated, the healthcare provider should inform public health authorities.

Should I get the COVID-19 vaccine if I had COVID-19?

Yes, you should be vaccinated regardless of whether you already had COVID-19.