Booster? Third Dose? What’s the Difference?

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You’ve probably heard…Pfizer booster doses are now authorized for certain individuals. But what does this mean? And what is the difference between a Booster and a third dose? After all, haven’t third doses been available for a while now?

If you are confused, you’re not alone! Have questions? We’ve got your answers!

What’s the difference between a third dose and a booster?

These terms shouldn’t be used interchangeably! They do—in fact—mean two separate things.

A third dose (also known as an additional dose) is for people who are immunocompromised. Sometimes people who are immunocompromised do not build enough protection when they first get fully vaccinated. When this happens, getting another dose of a vaccine can help them build more protection against the disease. Third doses of Moderna or Pfizer vaccine are currently available for certain immunocompromised individuals.

A booster refers to a dose of a vaccine that is given to someone who built enough protection after vaccination, but that protection decreased over time (waning immunity). This is why you need a tetanus booster every 10 years, because the protection from your childhood tetanus vaccine wanes over time. Only Pfizer boosters are currently available for certain populations.

Am I eligible for a third dose?

Currently, the CDC is recommending that moderately to severely immunocompromised people receive a third dose. This includes people who have:

  • Been receiving active cancer treatment for tumors or cancers of the blood
  • Received an organ transplant and are taking medicine to suppress the immune system
  • Received a stem cell transplant within the last 2 years or are taking medicine to suppress the immune system
  • Moderate or severe primary immunodeficiency (such as DiGeorge syndrome, Wiskott-Aldrich syndrome)
  • Advanced or untreated HIV infection
  • Active treatment with high-dose corticosteroids or other drugs that may suppress your immune response

People should talk to their healthcare provider about their medical condition, and whether getting a third dose is appropriate for them.

A person receiving a third dose should get it at least 28 days after dose two. When possible, the individual should receive the same vaccine (Moderna or Pfizer) as the first two doses but may receive the other mRNA vaccine brand if the original vaccine is not available.

At this time, no third dose is recommended for people who had the Johnson & Johnson (J&J) vaccine. People who received J&J should not get a second dose of either J&J or a dose of an mRNA vaccine. Additionally, people with competent immune systems should not receive a third dose.

Am I eligible for a booster?

At this time, only Pfizer Boosters are authorized, and are only for specific groups. First off, only those who received a first and second dose of Pfizer COVID-19 vaccine should seek out a booster dose at this time. Those who initially received Moderna or J&J will need to wait (see more about this below).

It is recommended that the following people receive a Pfizer booster dose:

  • People 65 and older
  • People 18 and older living in long-term care settings
  • People 50 – 64 with underlying medical conditions or those at increased risk of social inequities

Additionally, the following people may receive a booster dose of the Pfizer vaccine:

Eligible people will need to wait to receive their Pfizer booster until at least 6 months after their second dose of Pfizer. This means that—at the time of this article—only those who received their second dose in March or earlier should seek out a booster.

Additional populations may be recommended to receive a Pfizer booster shot as more data become available.

Is a third dose or booster really necessary?

A third dose may prevent serious and possibly life-threatening COVID-19 disease in people with compromised immune systems who may not have responded to their initial vaccine series.

Although we still have much to learn, early findings are very encouraging. Research published by the Israeli Health Ministry suggests that a third dose of the Pfizer-BioNTech COVID-19 vaccine significantly improves protection for those 60 and older from infection and serious illness, compared to those who received just two doses.

As for boosters, the COVID-19 vaccines continue to be very effective at reducing the risk of severe disease. Data show that protection against COVID-19 from vaccination begins to decrease over time as it does with other diseases like tetanus or whooping cough.

Paired with the dominance of the delta variant, we are starting to see evidence of reduced protection against mild and moderate disease. As a result, the CDC now recommends booster shots for certain individuals to increase—and extend—protection against the virus.

What if I got Moderna or the J&J single dose vaccine?

At this time, there are not yet booster recommendations for people who received the Moderna or J&J COVID-19 vaccines. The CDC and FDA will evaluate data in the coming weeks and may make additional recommendations for other vaccine types.

How can I make an appointment?

If you’re looking for a third dose of Moderna or Pfizer vaccine, talk with your health care provider first to make sure that a third dose is right for you. If so, there are many vaccine provider locations available to you, including the Skagit County Fairgrounds.  

Looking for a Pfizer booster? Use the Vaccine Locator online tool, check in with your local pharmacy, or give the COVID Hotline a call at 1–800–525–0127, then press #.

Folks can also schedule an appointment for a Pfizer booster at the Skagit County Fairgrounds. To make an appointment, use the PrepMod online appointment finder and search for “Skagit County Public Health” under Name of Location.

Please note that appointments are limited at this time. If no appointments appear when you search, check back the following Monday for newly added appointments. The COVID Hotline is also available if you need further assistance: 1–800–525–0127, then press #.

What should I bring with me?

When seeking out a third dose or booster, please remember to bring your Vaccination Card with you! Can’t find it? Visit MyIR Mobile to pull your vaccination record or call the State COVID-19 Hotline for assistance at 1–800–525–0127, then press #.


To those who are fully vaccinated: We still need your help!

Reading Time: 3 minutes

I have been fully vaccinated for some time now. As a Public Health employee and a part-time staff person at the Fairgrounds Vaccine Site, I was given the opportunity to receive my vaccine back in January. I cannot tell you how excited I was to get my second dose, knowing that I would soon (in two weeks) be protected from this virus that has ransacked our lives since last spring.

Over the past several months, I have watched my friends and loved ones receive their doses as well. I have also seen thousands upon thousands of Skagitonians come through our Vaccine Site, all rolling up their sleeves with a glimmer of hope in their eyes. There has been no greater gift than watching my community getting vaccinated and hearing the stories that people share.

I’ve also watched these same individuals walk out of our Observation Room, pull off their masks, and continue to walk through the parking lot carefree. This has been so incredibly concerning to watch.

You, our fully vaccinated residents, can be our number one advocates for safety and precaution. By taking the time to get vaccinated, you have essentially done just that! You are showing your friends, neighbors, and family members that you believe in the power of science, and that you are willing to take actions against COVID-19. You—my fully vaccinated peers—can be a powerful force!

So, I am pleading with you now: Please, please continue to wear your mask in public. And please, continue to limit your social gatherings though it is so incredibly tempting to do otherwise.

Trust me—I get it. There is nothing else that I’d rather do right now than have a barbeque with all of my friends and throw my mask in the dirt. I want to see my mother who lives in Canada and who I haven’t seen in over a year. I want to send my babies to daycare each day without worrying about their health and safety. But I can’t do this right now, whether or not I have received my vaccines. We just aren’t to that point yet.

We are making incredible strides, Skagit County. Our vaccination numbers are great and ever increasing. We now have just over 30% of our eligible residents fully vaccinated, and 40% well on their way with one vaccine to their name. That said, there are still many people who haven’t gotten vaccinated (whether by choice or because they haven’t been eligible or have been underage). These individuals need your help right now in order to stay safe. Your choices—daily—can make a life or death difference. I know that this isn’t a responsibility that I hold lightly.

Together, we can show people that we care and that we are willing to fight. By continuing to wear our masks in public, we are communicating a message to our fellow Skagitonians: that masking should be the norm for right now. That science works. That we care. I’d also hate for someone who isn’t vaccinated to see me walking around sans mask, since they wouldn’t know that I’m fully vaccinated. They’d just assume that I don’t care.

Our case numbers are going up right now. The Governor has now coined it as the “forth wave.” I am sick of this and sick of COVID. And I know you are too. But we know that wearing our masks can make a big difference—heck, it has saved so many lives already. Let’s continue to make progress. We don’t want to move backward; not economically with our reopening, or emotionally (you feel me right?).

Thank you for getting vaccinated. From the bottom of our hearts at the Fairgrounds: Thank you! Now let’s be the change that we want to see in the world. Let’s mask up for each other.

And if you’re wondering then what the point of getting vaccinated is if you can’t get rid of the mask all together, I also get that. There are many benefits to getting vaccinated, both for health and safety reasons…but also for fringe benefits as well! For updated CDC guidelines around travel, gathering, and mask wearing for fully vaccinated folks, visit: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated.html.