Should you get a third dose of COVID vaccine?

September 28, 2021 5:00 AM

A guide to the new CDC recommendations about who might benefit from a booster or third dose of the COVID-19 vaccines

Three syringes with vaccine on orange background
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This article was last updated on September 28, 2021.

Hundreds of millions of people in the U.S. have rolled up their sleeves to be vaccinated against COVID-19. With a new pronouncement from the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC), many millions may be going back for another dose.

After reviewing the data and a somewhat contentious debate over whether third doses were necessary for everyone, experts have come to agree that certain people should consider getting a third, booster dose of the vaccine for COVID-19.

The FDA and CDC had already approved and recommended an additional dose of mRNA COVID-19 vaccines as part of a primary series for moderately and severely immunocompromised people in August.

Here, we breakdown what the new recommendations mean for everyone in a quick, easy-to-understand guide.

New recommendations for COVID vaccine booster doses by population group

People over 65

Those who have been vaccinated should be assured that overall, the vaccines work to reduce the risk of severe disease. Data collected by the CDC shows that unvaccinated people 65 and older are 13 times more likely to be hospitalized with COVID-19 than those who are vaccinated.

Yet, while all of the vaccines are still highly effective at preventing severe illness, hospitalization and death, the number of infections in vaccinated people, particularly those over age 65, began to concern researchers in both in the U.S. and abroad.

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“People over 65 are not as well protected with the vaccines as they were with the emergence of the delta variant, so they should get a booster,” says Pamela Rockwell, D.O., FAAFP, a Michigan Medicine family physician and professor in the department of family medicine at the University of Michigan Medical School. She represents the American Academy of Family Physicians on the CDC’s Advisory Committee for Immunization Practices (ACIP) that just approved the new recommendation.

"People over 65 are not as well protected with the vaccines as they were with the emergence of the delta variant, so they should get a booster."
Pamela Rockwell, D.O.

All of the vaccines appear to lose a bit of effectiveness over time, as people’s immunity naturally wanes with time. And this fact combined with the emergence of the highly contagious delta variant of the coronavirus has led to more infections.

ACIP came to its decision by balancing the benefits and risks of a third dose of vaccine. They determined that the benefits of the vaccine--avoiding infection and possible hospitalization--far outweighed any risk of side effects such as swollen lymph nodes or myocarditis, a rare side effect that has been reported mostly in younger men who have received an mRNA COVID-19 vaccine.

Currently, the booster is only approved for people who have received the two-dose Pfizer mRNA vaccine more than six months ago. This is because Pfizer was the first to apply for approval of a booster dose from the FDA, but Moderna and Johnson & Johnson are expected to apply for approval of a booster dose of their vaccines soon, explained Rockwell. Recipients of these vaccines should hold tight, she said.

Future ACIP meetings will discuss mixing and matching mRNA vaccines for non-immunocompromised individuals. Said Rockwell, “my advice, until there is more data, is to not mix and match.”

People living in long-term care facilities

Adults living in long term care facilities like nursing homes are particularly vulnerable to infections, given their age, underlying health conditions and increased exposure from living in a group setting. CDC also recommends that they get a booster dose for more protection.

People age 50-64 with health conditions

The data for people with underlying health conditions—like heart disease or obesity—was mixed, with some evidence of waning immunity in people with at least one health problem, especially with the delta variant.

Again, because the benefits currently outweigh the risks, CDC recommends that people with underlying health conditions who are 50-64 should get a booster.

People age 18-49 with health conditions

Small studies have showed that people who get a third dose of mRNA vaccine have an increase in antibody levels and a subsequent reduction in infections. This may be of relevance to people who have other health problems that put them at risk for severe COVID-19 disease.

However, the overall benefit for a booster appears smaller for this age range, so CDC recommends that people aged 18-49 with underlying medical conditions may get a booster based on individual benefit and risk.

People in high risk professions

People with a lot of exposure to the public, like healthcare workers, daycare providers, teachers, and grocery store cashiers, are also at increased risk of exposure to the coronavirus. Because of this, many of these people were prioritized for the vaccines more than six months ago. Some studies showed a boost in antibody levels and an accompanying reduction in infections in people who received a third dose.

Reduced infections could mean fewer people in isolation and quarantine, currently required for many who test positive, even if they don’t have symptoms.

Wanting to base their decision on available data, ACIP did not vote to recommend that this group get a booster, because there is limited data to suggest this group is less protected against severe illness requiring hospitalization with the current vaccines.

However, Rochelle Walensky, M.D., director of the CDC, overturned this decision, saying, “it is my job to recognize where our actions can have the greatest impact. At CDC, we are tasked with analyzing complex, often imperfect data to make concrete recommendations that optimize health. In a pandemic, even with uncertainty, we must take actions that we anticipate will do the greatest good.”

This group is now eligible for a booster on individual benefit and risk and should discuss the option with their physician if they have questions.

People who are immunocompromised

People who are moderately to severely immunocompromised, either due to a condition such as cancer or HIV or due to medications they are taking, are not as well protected with the COVID vaccines.

Immunocompromised people are more likely to get severely ill from COVID-19, are at higher risk for prolonged viral infection and shedding of the virus, are more likely to transmit the infection to people they live with and show a lower immune response to vaccination compared to non-immunocompromised people, said Rockwell.

This group’s recommendation is slightly different in that it also includes immunocompromised people who received the Moderna mRNA vaccine, and the timing is much sooner than for other, non-immune compromised groups.

Their additional dose should ideally be the same mRNA COVID-19 vaccine as the first two shots the person received before but may be either mRNA vaccine, and should be administered at least 28 days after completion of the initial primary series of two shots.

This is not considered a “booster shot,” but rather an additional dose to the recommended use of COVID-19 vaccines in these individuals to complete their primary series of COVID-19 vaccination. It’s recommended because moderately to severely immunocompromised individuals have likely not produced an adequate immune response after getting two doses of an mRNA COVID-19 vaccine, considered a primary series for vaccination against COVID-19 for all others. 

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Currently there is not data to support giving an additional dose of mRNA COVID-19 vaccine to immunocompromised people whose previously received the one-dose Johnson & Johnson/Janssen vaccine. A recommendation for immunocompromised people who got that vaccine is still being developed.

“As COVID-19 surges across the country, vaccinated people who are moderately-severely immunocompromised and have completed a two-dose series of either the Pfizer or Moderna COVID-19 vaccine series should ideally obtain a third dose of the same mRNA vaccine that they have already received, and if not available, a third dose of an available mRNA vaccine, at least 28 days from their second vaccine dose. This includes children and adolescents 12 and older who are immunocompromised,” said Rockwell.

“If you aren’t sure if you or your child falls into this group, talk with a trusted health care provider,” she added. “And if you fall into the third-dose group, but you haven’t gotten vaccinated at all yet, or haven’t finished your two-dose series, now’s the time to do it.”

Other steps immunocompromised people should take

Vaccination is not all people in this group should do, she adds.

“It’s important for immunocompromised people to wear masks in public, maintain social distancing of at least 6 feet from people they do not live with, avoid crowds and poorly ventilated indoor spaces until advised otherwise by their healthcare provider, and to encourage everyone over the age of 12 who interacts with them closely to get vaccinated if they aren’t already,” she said.

“They may not realize how much they are putting you at risk, or that your immunocompromised state puts you at high risk of severe COVID-19,” she added. “Ask them to help protect you.”

Rockwell also encourages people who get a third dose of COVID-19 vaccine to sign up for the CDC’s V-safe system which will text them occasionally to ask them to report any reactions to the vaccine. This will help collect data that will guide the vaccination process and look for any rare effects.

SEE ALSO: If I’m Immunocompromised, Should I Keep Wearing My Mask Once I’m Vaccinated?

While the overwhelming majority of people hospitalized for COVID-19 right now are unvaccinated adults and children, many of the rest of those in hospitals for COVID-19 care have a condition or take a medication that affects their immune system.

Who is considered moderately to severely immunocompromised

If you have fall into one of the categories below as defined by the CDC as those individuals moderately-severely immunocompromised, contact your health provider or your child’s provider to see whether they recommend a third dose.

  • 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 two 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 (>20 mg prednisone/day for at least two weeks)

What’s next?

The FDA and CDC continue to monitor how well vaccines are protecting people in the real world to try and make the best decisions possible to protect public health, and these new recommendations are subject to change as even more data is collected.

Ending the pandemic will take more than just vaccination, including booster doses. Until cases are brought under control, wearing masks, improving indoor ventilation and other public health measures will be needed to slow the spread of COVID-19 and prevent hospitalization. However, getting shots to the 45 percent of the U.S. population who are not fully vaccinated will go a long way to ending the current crisis and as such, remains a top priority for the CDC and other health professionals.