Should I Get the COVID-19 Booster?

Recommendations for getting the COVID-19 booster vaccine keep getting stronger. Now, everyone ages 12 and and older can get a booster shot after their initial vaccine series, according to the Centers for Disease Control and Prevention.

Real-time research already suggests that booster shots enhance protection from becoming infected or experiencing severe COVID-19 disease. These are the latest recommendations and guidelines for COVID-19 boosters:

— Everyone 12 and older should get a booster dose. Teens ages 12 to 17 can only get a Pfizer vaccine booster.

— Those who completed a Pfizer vaccine series are eligible for a booster five months after, or those who completed a Moderna vaccine series are eligible for a booster six months after.

— Those who initially received the J&J vaccine should get the booster two months after.

— You can choose which type of booster you receive — it’s OK to mix and match.

— You’re still considered fully vaccinated if you don’t get a booster but have completed the initial two-dose Moderna or Pfizer series, or you received the initial single-dose J&J vaccine, according to the CDC.

“Data show that COVID-19 boosters help broaden and strengthen protection against omicron and other SARS-CoV-2 variants,” according to a Jan. 5 statement from CDC Director Dr. Rochelle Walensky.

Only two months prior, as the prevailing delta variant fueled the ongoing pandemic, the CDC advised that all adults under 65 were allowed to receive a booster, but with less urgency. “Booster shots have demonstrated the ability to safely increase people’s protection against severe outcomes and are an important public health tool to strengthen our defenses against the virus as we enter the winter holidays,” according to a Nov. 19 statement from Walensky.

Most recently, new data suggests that getting a booster can indeed help protect against the omicron variant. On Dec. 8, Pfizer reported that in preliminary laboratory studies, three doses of the Pfizer vaccine increased antibodies that “neutralize” the omicron variant.

[SEE: Photos: Doctors, Nurses and Hospital Staff Fight Coronavirus Pandemic.]

Supporting Evidence

Boosters significantly increase protection against COVID-19 for people who already received the primary vaccine series, according to a massive study from Israel, published online Nov. 30 in JAMA Internal Medicine. The study of nearly 307,000 adults ages 40 and older, all of whom had received the initial two-dose Pfizer vaccine series, compared participants who either did or did not go on to receive the booster.

There were significantly reduced odds — 86% lower — of testing positive for COVID-19 infection within a few weeks of receiving the booster compared with only having the primary vaccine series. Hospitalization odds were also lower for participants who had booster shots, researchers found. Visit the CDC website for in-depth details on COVID-19 booster shots.

Extra Protection

If anything, receiving your booster shot may feel more routine, with less fanfare than getting your first COVID-19 vaccine. Initial vaccines came with a flourish, often at mass vaccination sites in convention centers and arenas, complete with uniformed Federal Emergency Management Agency officials.

In comparison, the booster experience seems almost mundane. Now, you’re likely to get your booster shot with little ceremony at the local pharmacy or county health department.

Although the initial vaccine series was more consequential in terms of taking most people from zero to extremely high protection against COVID-19, booster shots extend that protection significantly. That’s because the body’s immune response may fade somewhat months after the initial series.

“Although COVID-19 vaccination remains effective in preventing severe disease, recent data suggest vaccination becomes less effective over time, especially in people aged 65 and older,” according to the CDC booster webpage. In addition, effectiveness wanes in terms of preventing infection or milder illness with symptoms.

For health care and other front-line workers — among the first groups to be vaccinated — effectiveness against infection is also decreasing. “This lower effectiveness is likely due to the combination of decreasing protection as time passes since getting vaccinated, as well as the greater infectiousness of the delta variant,” the CDC explains.

A large study of vaccine effectiveness over time analyzed data for nearly 3.5 million members of a Southern California health system who were fully vaccinated with the Pfizer vaccine against COVID-19. The average age of participants was 45 years old. Among study findings, published Oct. 19 in The Lancet:

— Effectiveness against infection was initially 88% after the first month on average, waning to 47% after five months.

— Effectiveness against infection by the delta variant was 93% after the first month, waning to 53% after four months.

— Effectiveness against non-delta variants was 97% after the first month, waning to 67% after four to five months.

— Effectiveness against hospitalization for those infected with the delta variant remained high at 93% up to six months.

The most important step is getting vaccinated in the first place, experts emphasize. If you’ve received the primary vaccine series but still haven’t gotten a booster, you still have much better protection against COVID-19 than those people who are still unvaccinated.

[See: What Are the Symptoms of Coronavirus?]

Omicron Factor

On Dec. 1, the first U.S. case from the omicron variant was reported in California. As of Dec. 20, omicron has been detected in most states across the country.

If people are eligible to receive a booster shot, it makes sense to do so, says Dr. Albert Shaw, a professor of medicine in the section of infectious diseases at Yale School of Medicine in New Haven, Connecticut.

“It’s a good idea to get it, particularly with this unknown quantity of the new variant that we’re only just now learning about,” Shaw says. “We’re kind of entering new territory with omicron. Maximizing the immune response that you have is probably a good idea.”

Information on the effectiveness of booster shots is happening in real-time, Shaw says, so there isn’t a lot of long-term, follow-up data available yet. “We certainly know from laboratory studies that the levels of protective antibodies increase substantially after the booster dose,” he says. He also points out that large observational studies from Israel among people vaccinated against COVID-19 suggest that the boosters really seem to be effective compared with receiving the initial vaccine series alone.

Booster Side Effects and Details

Booster shot side effects reported so far are similar to those of the initial COVID-19 vaccine series, or milder depending on the recipient. Arm pain and redness at the injection site, fatigue and headaches are the most commonly reported booster side effects so far. Muscle and joint pain, fever and chills, swollen lymph nodes in the arm where the shot was given, and nausea and vomiting are also common. As with the first COVID-19 series, a rare but severe allergic reaction called anaphylaxis — possible after any type of vaccination — can happen.

Booster shots have the same formulations, or ingredients, as the primary COVID-19 vaccine series. The dosage also remains the same for the Pfizer and J&J boosters as for their initial vaccines. However, dosage is different for the Moderna booster vaccine — it’s half the dose of the Moderna primary series, Shaw notes.

Third Doses and Booster Shots for Most Vulnerable

A booster shot causes “B cells” — immune system cells that make antibodies — to multiply, raise antibody levels again and to produce an even stronger, more rapid response to future virus exposures.

Vaccine experts emphasize the difference between a booster shot versus a third dose of the COVID-19 vaccine for immunocompromised or other vulnerable people:

Booster shot. A healthy person who gets two doses of the mRNA vaccine develops a good antibody response and a high immunity level against COVID-19, explains Dr. Kathleen Neuzil, a professor in vaccinology and director of the Center for Vaccine Development and Global Health at the University of Maryland School of Medicine. The booster is given to augment immunity that already exists, should it start to fade after a period of months or a year.

Third dose. An immunosuppressed person often fails to reach a basic, protective immune response after those initial two vaccine doses, Neuzil says. Fortunately, she adds, “After three doses, many more of them get there.”

Now, some immunocompromised people may receive an additional booster dose, beyond the additional dose they may already have received. According to the CDC webpage on vaccines for moderately to severely immunocompromised people, updated on Jan. 4:

— Those 5 and older who received a primary Pfizer series should get an additional (third) dose. Those 12 and older are eligible to receive a booster dose, as well.

— Those 18 and older who received a primary Moderna series and additional (third) dose are eligible to receive a booster dose, as well.

— Those 18 and older who received the single-dose J&J series, although not recommended to get an additional primary dose, should get a booster shot at least two months after their initial (single) J&J primary shot.

People may be immunosuppressed for various reasons, including:

— Active or recent cancer treatment.

— Solid organ or stem cell transplant.

HIV infection that’s advanced or untreated.

— Medications such as high-dose steroids, chemotherapy drugs, tumor-necrosis factor (TNF) blockers used to treat inflammatory conditions like rheumatoid arthritis.

— Medical conditions like chronic kidney disease that can weaken the immune system.

In August 2021, a third COVID-19 vaccine was initially recommended for people on medications that suppress the immune system, such as certain rheumatology patients or those who’ve undergone a transplant, as well as for cancer survivors. For some, that additional dose is raising antibody levels above the threshold needed for protection against COVID-19:

— Administration of a third dose of the Pfizer vaccine “significantly improved the (ability to elicit an immune response) of the vaccine, with no cases of COVID-19 reported in any of the patients” for 101 patients with solid organ (kidney, liver, lung, heart or pancreas) transplants, in a study published August 12 in the New England Journal of Medicine.

— Similarly, a third dose of the Moderna vaccine produced an increased COVID-19 antibody response in another study of 120 solid-organ transplant patients. The response rate was 55% among those who received the additional dose, versus 18% who received a placebo injection in the comparison study.

“It’s a really important statement that the CDC has authorized the third dose, the emergency use authorization, in the setting of immunocompromised patients,” Dr. David Cohn told U.S. News when the third dose was approved. Cohn is the chief medical officer at the Ohio State University Comprehensive Cancer Center, a professor in gynecologic oncology and a practicing gynecologic oncologist.

“Patients who are immunocompromised at baseline have a higher risk of contracting COVID because their immune systems are weakened,” Cohn says. “And if they were to get COVID, they’d have a higher rate of severe complications or death, and hospitalization from COVID. So, it’s a really important population to target.”

Cancer patients have been eager to get the extra protection an additional dose could afford. “When we offered vaccination for our cancer patients, they were the first ones in line when their number got picked by the state of Ohio, and I’m sure it’s the same across the country,” Cohn says. “They were really excited to get back to some level of normalcy. And when the CDC authorized the third dose for this population, they were literally lined up at our door waiting to be vaccinated again.”

Approval for boosters or third doses takes several steps. That includes emergency use authorization by the Food and Drug Administration and a recommendation by the Advisory Committee on Immunization Practices at the CDC, which endorses the ACIP recommendation.

[SEE: What to Say to Friends or Family Members Who Hesitate to Wear a Mask.]

Staying Vigilant

Having a booster still doesn’t mean that other COVID-19 prevention methods — masks and social distancing — aren’t needed anymore. “I don’t view them as mutually exclusive,” Shaw says. It’s still unknown how well boosters work against omicron, he points out. “Certainly, one would hope that like with the other variants we’ve seen, there would still be protection against the most serious outcomes of disease, hospitalizations or death.” Whether or not that’s the case, he adds, “I certainly think there would be concern about limiting transmissions — particularly for people with members of the family who may have preexisting medical conditions or who are older.”

If you get the third dose, continue to practice caution. “The safest guidance for those at the highest risk for contracting COVID or getting severe disease from COVID is still to be vaccinated and act unvaccinated,” Cohn says.

A key, persistent issue is that many Americans still remain unvaccinated against COVID-19 altogether. “By this time, we’ve had hundreds of millions of Americans who have been vaccinated,” Shaw says. “We really think the vaccines are safe. They seem to be highly effective and there is emerging data that booster shots may help up. And particularly with this new variant, it’s reasonable to incorporate vaccines and boosters as part of this strategy of keeping everybody safe over the holidays.”

More from U.S. News

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Should I Get the COVID-19 Booster? originally appeared on

Update 01/06/22: This story was previously published at an earlier date and has been updated with new information.

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