Since they’ve been introduced, COVID-19 vaccines have been the best way to protect yourself and others from the coronavirus. But there are a lot of questions about the doses that come after the initial vaccines, such as: What’s the difference between a booster shot and an immunocompromised dose? When should you get a booster dose? And is the initial vaccine still effective?

We answer these questions and more below.

Booster shot vs. immunocompromised dose: Is there a difference?

Yes. There’s a difference between COVID-19 vaccine booster shots and immunocompromised doses. Though they are both an additional shot of the vaccine, they’re used for different reasons which we’ll get into in the following sections.

What is a COVID-19 booster shot?

The COVID-19 booster shot is a dose of the vaccine that’s used to increase the original vaccine's level of effectiveness and extend the length of protection.

Why would I need a COVID-19 booster shot?

Receiving the initial COVID-19 vaccine and the booster dose is the best way to protect yourself against getting sick. Even if you got a breakthrough case of COVID-19, you should still get a booster after you’ve recovered.

Data from the Centers for Disease Control and Prevention (CDC) shows that COVID-19 vaccines and booster shots continue to be effective against the coronavirus, and greatly reduces the severity of symptoms if you get a breakthrough case.

During the Omicron spike, getting a booster dose greatly increased protection against COVID-19. People who had received booster shots were 23 times less likely to be hospitalized than people who weren’t vaccinated.

How are booster shots different than the vaccine shots?

The booster shots are a dose of the same, approved COVID-19 vaccines. The Pfizer and Johnson & Johnson boosters contain the same dose as the original vaccine, while the Moderna booster is a half-dose of the original.

Does the need for additional shots mean that the COVID-19 vaccine isn't effective?

No. An available COVID-19 booster shot doesn’t mean there’s anything wrong with the COVID-19 vaccine. Rather, this is what normally happens with many vaccines – your immune response can decrease over time.

That’s why there are booster shots for illnesses such as chickenpox, tetanus, mumps and measles, to name a few – and why you should get a flu shot every year.

Who’s eligible for a COVID-19 vaccine booster shot?

All fully vaccinated people over the age of 5 are eligible to receive at least one COVID-19 booster shot.

How long is the COVID-19 booster shot effective?

The CDC continues to research how long booster shots protect against COVID-19. Based on recent data, booster shots provide good protection for at least four months. Does that mean a second booster shot is in your future? It depends on your age and health factors.

Who’s eligible for a second COVID-19 booster shot?

A second booster shot is most beneficial to those who are more likely to get severe COVID-19. People most at risk include those who are immunocompromised, over 65 years old, or over 50 years old with chronic medical conditions such as obesity, diabetes, kidney disease, cardiovascular disease, high blood pressure and lung disease.

You’re also eligible for second booster if you’re:

  • At least 50 years old.
  • At least 18 years old and have received Johnson & Johnson vaccine for your initial vaccine and first booster shot.
  • At least 12 years and moderately to severely immunocompromised.

If a second booster hasn’t been authorized for you, it means that, based on your age and health factors, one booster dose still provides good protection against COVID-19.

Which booster shot can I get? Can you mix vaccines?

According to the CDC, mRNA booster shots (Pfizer or Moderna) are recommended over the Johnson & Johnson booster shot – regardless of your initial COVID-19 vaccine.

As far as which of the mRNA booster shots you can get, there’s some flexibility. Getting another dose of your initial COVID-19 vaccine will, undoubtedly, boost your protection. But studies show that a mix-and-match approach for booster shots can be valuable, especially if the vaccines are based on different technology. For example, someone who originally received the viral vector vaccine from Johnson & Johnson may get even more protection from a booster dose of a mRNA vaccine like Moderna. You can also mix up mRNA doses and get the Pfizer booster after the Moderna vaccine or the other way around.

However, any booster shot will increase your protection against COVID-19. So, we recommend getting the booster shot that’s available to you.

When to get a COVID-19 booster shot based on your initial vaccine

The timing of your booster shot depends on your initial vaccine, your age and whether you’re immunocompromised (we’ll get into the timing of booster shots for immunocompromised people later in this post).

Age Type of initial vaccine 1st booster shot timing 2nd booster shot timing Type of booster vaccine to get
5-17 years old Pfizer 5 months after last dose Not applicable Pfizer
18-49 years old Pfizer or Moderna 5 months after last dose Not applicable Any
18-49 years old Johnson & Johnson 2 months after last dose 4 months after 1st booster Any
50+ years old Pfizer or Moderna 5 months after last dose 4 months after 1st booster 1st booster – any

2nd booster – Pfizer or Moderna

50+ years old Johnson & Johnson 2 months after last dose 4 months after 1st booster 1st booster – any

2nd booster – Pfizer or Moderna

What is a COVID-19 immunocompromised dose?

For most people, receiving the prescribed doses of the COVID-19 vaccine (two for Moderna and Pfizer; one for Johnson & Johnson) causes enough of an initial immune system response to protect them from falling ill with COVID-19.

But for people with weakened immune systems, the initial vaccine may not produce enough protective antibodies to prevent them from getting the disease – especially with new, more contagious strains of COVID-19 emerging. In these cases, people may need an additional dose of a COVID-19 vaccine for full protection.

Who is eligible for a COVID-19 vaccine immunocompromised dose?

People over the age of 5 years old who are moderately to severely immunocompromised and received the Moderna or Pfizer COVID-19 vaccine are eligible to receive an additional dose 28 days after their second dose. Usually, an immunocompromised dose is given 28 days after your second dose, but your doctor may suggest different timing based on what they think you need.

You may be considered immunocompromised if you:

  • Had an organ transplant
  • Had stem cell transplants within the past two years
  • Have severe primary immunodeficiency
  • Are being treated for active cancer
  • Have advanced or untreated HIV
  • Are being treated with drugs that may suppress your immune system, such as high-dose corticosteroids

Which immunocompromised dose can I get?

Your immunocompromised dose is usually from the same vaccine manufacturer as your initial series. If you received two doses of Pfizer previously, your additional dose should be Pfizer. If you received two doses of Moderna, your additional dose should be Moderna. But if you got the Johnson & Johnson vaccine, you should get the Moderna or Pfizer vaccine as a booster dose.

When should I get an immunocompromised dose and booster shot?

The following is the typical timing of additional doses and booster shots for people who are immunocompromised. But your doctor may suggest different timing or additional doses, based on what they think is best for you.

Immunocompromised dose Booster shot
Age Type of initial vaccine Dose timing Type of vaccine 1st booster timing 2nd booster timing Type of vaccine
5-11 years old Pfizer 28 days after last dose Pfizer 5 months after immunocompromised dose Not applicable Pfizer
12-17 years old Pfizer 28 days after last dose Pfizer 3 months after immunocompromised dose 4 months after 1st booster Pfizer
18+ years old Pfizer and Moderna 28 days after last dose Same as initial vaccine 3 months after immunocompromised dose 4 months after 1st booster 1st booster – any

2nd booster – Pfizer or Moderna

18+ years old Johnson & Johnson 28 days after last dose Pfizer or Moderna 3 months after immunocompromised dose 4 months after 1st booster 1st booster – any

2nd booster – Pfizer or Moderna

Even after you get an immunocompromised dose, it’s still recommended you continue to take other steps to avoid getting COVID-19, including wearing a mask and avoiding large crowds.

If you’re eligible for a third dose and received your initial vaccines through HealthPartners, you likely have already received an email or text message from us and can schedule your next dose online. But you don’t have to be a HealthPartners patient to schedule your immunocompromised dose.

If you’re not sure if you’re eligible, call one of our nurse lines – HealthPartners CareLine℠ at 800-551-0859 or the Park Nicollet Nurse Line at 952-993-4665.

Are COVID-19 vaccine booster shots and immunocompromised doses safe?

Yes. COVID-19 booster shots and immunocompromised doses are the same as your earlier doses. The COVID-19 vaccines are incredibly safe – they’ve protected millions of people against COVID-19, usually with few side effects.

What are the possible side effects of a COVID-19 vaccine booster shot or immunocompromised dose?

Do you remember the side effects you had with your initial vaccine dose(s)? Chances are that your side effects will be very similar this time around.

For most people, the common side effects are usually fatigue and feeling pain around where they got the shot. Less commonly, people experience headache, muscle pain, chills, fever and nausea. These side effects usually only last a couple days.

Moving forward as things change

It may seem like things with COVID-19 keep changing, and it’s true. Boosters and additional doses demonstrate that we’re learning more about COVID-19 so we can control the spread of the coronavirus and keep communities healthy.

We know that the vaccines work. According to the CDC, unvaccinated people are more likely to get COVID-19 than vaccinated people. There’s also a huge difference in the severity of symptoms between vaccinated and unvaccinated people. If someone who is vaccinated gets breakthrough COVID-19, they usually have mild COVID-19 symptoms that can be treated at home .

Getting vaccinated is still the best thing you can do to prevent COVID-19. And, getting the appropriate boosters or immunocompromised dose can help extend your protection against the coronavirus.