UPDATE: A U.S. Food and Drug Administration advisory panel on Thursday endorsed administering lower-dose booster shots of the Moderna vaccine. Read more here.
The first step toward authorizing booster shots for millions of Americans who received the Moderna and Johnson & Johnson COVID vaccines begins Thursday as a panel of outside of experts for the Food and Drug Administration meets to determine its recommendation.
Last month, the FDA authorized booster shots of Pfizer’s vaccine for older Americans and other groups with heightened vulnerability to COVID-19.
Here's what you should know about booster shots and what to expect:
What's happening this week?
Both Moderna and Johnson & Johnson have submitted requests for emergency use authorization of their booster shots of the COVID vaccines.
The FDA's panel of outside experts is expected to focus on Moderna Thursday and J&J Friday. It’s the first step in a review process that also includes sign-off from the leadership of both the FDA and the Centers for Disease Control and Prevention.
The process is meant to bolster public confidence in the vaccines. But it has already led to conflicts among experts and agencies — and documents the FDA released Tuesday suggest this week’s decisions will be equally difficult.
In a new review of Moderna's data, the FDA did not indicate Tuesday if it was leaning toward clearing the company's booster. It said vaccines used in the U.S. still provide protection, and it raised questions about some of Moderna's data.
FDA staff similarly didn't take a stance on Pfizer's COVID booster shots last month. That didn't stop the agency's Vaccines and Related Biological Products Advisory Committee from recommending third shots.
The two initial Moderna shots contain 100 micrograms of vaccine each. But the drugmaker says 50 micrograms ought to be enough for a booster for healthy people.
A company study of 344 people gave them a 50-microgram shot six months after their second dose, and levels of virus-fighting antibodies jumped. Moderna said the booster even triggered a 42-fold rise in antibodies able to target the extra-contagious delta variant.
In an online review posted Wednesday, FDA scientists also didn't reach a firm conclusion about whether there's enough evidence for J&J boosters, citing shortcomings with the company's data and little information on protection against the extra-contagious delta variant of the coronavirus.
J&J also complicated the decision by proposing a second shot over a range of two to six months. The company said in its FDA submission that a six-month booster is recommended but that a second dose could be given at two months in some situations.
For its part, J&J filed data with the FDA from a real-world study showing its vaccine remains about 80% effective against hospitalizations in the U.S.
FDA reviewers wrote that a study of the two-month booster plan suggests “there may be a benefit," while pointing to only small numbers of people who got another shot at six months instead.
Overall, the J&J vaccine "still affords protection against severe COVID-19 disease and death," the FDA's reviewers concluded. But data about its effectiveness “are consistently less” than the protection seen with Pfizer and Moderna shots.
When the FDA's panel meets to review the Moderna and J&J vaccines, experts will discuss whether a third Moderna shot should contain just half the original dose and what’s the best timing for a second shot of the single-dose J&J vaccine.
The panel will also look into the safety and effectiveness of mixing-and-matching different brands of vaccine, something regulators have not endorsed so far.
An estimated 103 million Americans are fully vaccinated with Pfizer’s formula, 69 million with Moderna’s and 15 million with J&J’s, according to the CDC. Regulators took up the question of Pfizer boosters first because the company submitted its data ahead of the other vaccine makers.
Scientists emphasize that all three vaccines used in the U.S. still offer strong protection against severe disease and death from COVID-19. The issue is how quickly, and how much, protection against milder infection may wane.
When could booster shots for Moderna and J&J be decided?
The final go-ahead is not expected for at least another week.
After the FDA advisers give their recommendation, the agency itself will make a decision on whether to authorize boosters. Then next week, a panel convened by the Centers for Disease Control and Prevention will offer more specifics on who should get them. Its decision is subject to approval by the CDC director.
If both agencies give the go-ahead, Americans could begin getting J&J and Moderna boosters later this month.
"So Oct. 14, the FDA advisory committee will start considering Moderna boosters," Chicago Department of Pubic Health Commissioner Dr. Allison Arwady said. "So I would expect by... a week or two after that we should have guidance for people who got Moderna as their first series and similarly J&J probably. They'll consider these, I would guess, together so I'd say... before the end of October, I would expect that we would have guidance."
The CDC's advisory committee is next scheduled to meet on Oct. 20 and 21 to discuss the boosters.
While the FDA and CDC so far have endorsed Pfizer boosters for specific groups only, Biden administration officials, including Dr. Anthony Fauci, have suggested that extra shots will eventually be recommended for most Americans.
Who is already eligible?
- People 65 years and older and residents in long-term care settings should receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series,
- People aged 50–64 years with underlying medical conditions should receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine atleast 6 months after their Pfizer-BioNTech primary series,
- People aged 18–49 years with underlying medical conditions may receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series, based on their individual benefits and risks, and
- People aged 18-64 years who are at increased risk for COVID-19 exposure and transmission because of occupational or institutional setting may receive a booster shot of Pfizer-BioNTech’s COVID-19 vaccine at least 6 months after their Pfizer-BioNTech primary series, based on their individual benefits and risks.
What counts as a qualifying underlying health condition? Here's a list from the CDC:
- Chronic kidney disease
- Chronic lung diseases, including COPD, asthma (moderate-to-severe), interstitial lung disease, cystic fibrosis, and pulmonary hypertension
- Dementia or other neurological conditions
- Diabetes (type 1 or type 2)
- Down syndrome
- Heart conditions (such as heart failure, coronary artery disease, cardiomyopathies or hypertension)
- HIV infection
- Immunocompromised state (weakened immune system)
- Liver disease
- Overweight and obesity
- Sickle cell disease or thalassemia
- Smoking, current or former
- Solid organ or blood stem cell transplant
- Stroke or cerebrovascular disease, which affects blood flow to the brain
- Substance use disorders
In addition to the Pfizer authorization, officials have also cleared booster doses of both the Pfizer and Moderna vaccines for people with weakened immune systems.
According to the CDC, immunocompromised groups include 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
The agency notes that "people should talk to their healthcare provider about their medical condition, and whether getting an additional dose is appropriate for them."
What about mixing and matching vaccines?
Adding to the complexity is whether it's OK to use a booster that's a different brand than someone's initial shots.
Preliminary results of a U.S. government study suggest that mixing and matching boosters will work at least as well — and maybe far better for J&J recipients. Those people had a stronger immune response if they got either a Moderna or Pfizer shot as their booster than if they received another dose of the J&J vaccine, according to results posted online Wednesday.
Mix-and-match is also up for discussion by the FDA panel this week.
Are there any risks with getting a booster shot? What are the side effects of boosters?
Among people who stand to benefit from a booster, there are few risks, the CDC concluded. Serious side effects from the first two Pfizer doses are exceedingly rare, including heart inflammation that sometimes occurs in younger men. Data from Israel, which has given nearly 3 million people — mostly 60 and older — a third Pfizer dose, has uncovered no red flags.
The CDC has noted that side effects with the third shot "were similar to that of the two-dose series."
The most common symptoms include fatigue and pain at the injection site, but "most symptoms were mild to moderate."
For Moderna, side effects were similar to the fevers and aches that recipients commonly experience after their second regular shot, the company said.
As with previous doses of the vaccine, the CDC notes that, "serious side effects are rare, but may occur."
Am I still considered fully vaccinated if I don't get a booster?
Even with the introduction of boosters, someone who has gotten just the first two doses would still be considered fully vaccinated, according to the CDC's Dr. Kathleen Dooling. That is an important question to people in parts of the country where you need to show proof of vaccination to eat in a restaurant or enter other places of business.