Booster Shots & Third Doses: What you should know


A row of nine COVID vaccine vials.

It’s been a tough month. We’re seeing the delta variant spread like wildfire through our communities. COVID-19 transmissions have increased and state hospitalization rates have reached an all-time high. Unfortunately, this means we’ve had to return to some preventative measures like wearing masks again. Even though this may feel like a giant step backwards, there’s also some good news out there — the vaccines are working.

Even in the extremely rare breakthrough cases, the vaccines have been proven to prevent serious illnesses from COVID-19. And, we’re continuing to see the positive impact of vaccines to reduce the spread of the virus. Medical experts are carefully monitoring the effectiveness of the vaccines. They are trying to determine if (or exactly when) the lifesaving immunity provided by the vaccines decreases over time. This is known in the medical community as waning immunity.

Waning immunity is a part of normal biological response to some vaccines. It’s similar to how your muscles can shrink when you don’t use them. Waning effectiveness also occurs when a virus changes and the resulting variant is resistant to the vaccine. When immunity from a vaccine begins to wane, a booster dose may be needed to help “boost” immunity again. Knowing that medical experts are already thinking ahead to see if or when boosters may be needed is more great news.

Recently, the U.S. Food and Drug Administration (FDA) authorized a third dose of the vaccine for immunocompromised people. This is because their bodies have limited ability to learn how to make antibodies from the vaccine. For this small group of individuals, a third dose may help them create a more lasting immunity. So, upon hearing this, you might wonder, “do I need another shot too?” and that’s a great question. Read on to learn what you need to know about getting vaccinated again.

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

Though they’re often used interchangeably, there’s a distinction.

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.

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.

Am I eligible for one?

Both national and state-level expert advisory panels recommend additional doses of mRNA vaccines for some immunocompromised people, and this is what the FDA authorized. So, if your condition qualifies you for a third dose, and you got a Pfizer or Moderna COVID-19 vaccine, you’re eligible. Third doses should be given at least 28 days after dose two. You can also check out this CDC page to find out if a third dose is recommended based on your condition. Ask your health care provider if an additional dose is right for you.

If you got the Johnson & Johnson (Janssen) single-dose vaccine, you do not need to get another dose at this time, but you should check with your health care provider to see if they have other recommendations. Currently, additional doses of this vaccine are not authorized by the FDA.

Boosters are not currently recommended for any of the COVID-19 vaccines in the United States. However, that may change soon pending guidance from the FDA and the Advisory Committee on Immunization Practices who advise the Centers for Disease Control and Prevention. Following any updated recommendations, the Western States Science Advisory Committee reviews and provides recommendations for Washington. Although boosters are not currently recommended in the U.S., we’re preparing for the possibility that they may be offered in the future. We expect that people who were vaccinated early during Washington’s vaccine rollout — including many health care providers, nursing home residents, and older adults — may be the first who are recommended for a booster dose.

Is another dose or booster really necessary?

An additional 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. The CDC believes that booster shots may be needed to make vaccine-induced protection stronger and last longer.

How can I make an appointment?

Talk to your health care provider if you think you might need a third dose due to your medical condition. They can share more information about how to get a third dose if needed.

We’re still learning if and when boosters will be needed for most people. We will share more information about whether (or when) boosters are needed as it becomes available.

What if I got the Johnson & Johnson single dose vaccine?

Currently, additional doses are only recommended for eligible people who got an mRNA vaccine, like Pfizer or Moderna.

The CDC does anticipate that boosters may be needed for people who got the Johnson & Johnson vaccine, but they aren’t available quite yet. Since the Johnson & Johnson vaccine came out later than the others, experts need a little more data before making a recommendation.

More information

This blog is accurate as of the date of posting. Information changes rapidly, so check the state’s COVID-19 website for the most up-to-date info at You can also sign up to be notified whenever we post new articles.

The COVID-19 vaccine is now available to everyone 12 and older. For more information about the vaccine, visit and use the vaccine locator tool to find an appointment. The COVID-19 vaccine is provided at no cost to you.

WA Notify can alert you if you’ve been near another user who tested positive for COVID-19. Add WA Notify to your phone today:

Answers to your questions or concerns about COVID-19 in Washington State may be found at our website. You can also contact the Department of Health call center at 1–800–525–0127 and press # from 6 a.m. to 10 p.m. Monday, and 6 a.m. to 6 p.m. Tuesday — Sunday and observed state holidays. Language assistance is available.



Washington State Department of Health
Public Health Connection

Protecting and improving the health of people in Washington State.