Who should get COVID-19 booster shots. An older woman gets her vaccine at UCHealth Universtiy of Colorado Hospital in Aurora.

Millions more people across the U.S. now may get COVID-19 booster vaccine doses after leaders of the U.S. Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) authorized mix-and-match vaccines and provided long-awaited guidance to people who received Moderna and Johnson & Johnson (J&J) vaccines.

Research shows that COVID-19 vaccines are remarkably effective in preventing hospitalizations and deaths, but the effectiveness of vaccines wanes over time. Booster doses two months after a J & J vaccine or six months or longer after two initial doses of Pfizer or Moderna vaccines can jumpstart vaccine efficacy, bringing it back up to remarkably protective levels of about 95%.

Who should get booster shots?

Dr. Rochelle Walensky, head of the CDC, on Thursday night endorsed the guidance that medical experts at both the CDC and FDA had recommended. The new rules pave the way for J & J recipients to finally get booster doses. And, Americans are free to make their own choices about mixing and matching they types of vaccines that they receive. If those who got the single-dose J & J vaccine now want to pump up their immunities with an mRNA dose from Moderna or Pfizer, they are free to do so. Similarly, people who received doses of Moderna or Pfizer for their initial two doses may also get a different brand for their booster dose. They can do what’s most convenient and easiest for them.

Here’s the newest guidance:

For individuals who received a Pfizer-BioNTech or Moderna COVID-19 vaccine, the following groups are eligible for a booster shot at 6 months or more after their initial series:

For the nearly 15 million people who received a J & J COVID-19 vaccine, booster shots are also recommended for those who are 18 and older and who were vaccinated two or more months ago.

Health experts agree that the best way to end the pandemic as soon as possible is for all eligible unvaccinated people to get their first doses of vaccines as soon as possible. (Learn more about getting COVID-19 vaccines and booster doses.)

But, broad availability of COVID-19 booster shots will help drive down infections,

“These recommendations are another example of our fundamental commitment to protect as many people as possible from COVID-19. The evidence shows that all three COVID-19 vaccines authorized in the United States are safe – as demonstrated by the over 400 million vaccine doses already given. And, they are all highly effective in reducing the risk of severe disease, hospitalization, and death, even in the midst of the widely circulating Delta variant,” Walensky said in a statement October 21, hours after a CDC advisory panel unanimously endorsed new booster recommendations.

Added Dr. Michelle Barron, senior medical director of infection prevention at UCHealth:

“We know booster shots play an important role in the fight against COVID-19, and we’re still in the midst of a pandemic. Vaccine efficacy may diminish over time with the potential risk for increased susceptibility to breakthrough infections.”

COVID-19 infections and hospitalizations in Colorado remain very high, prompting Barron and others to urge people to get initial vaccines immediately and booster doses as soon as people are eligible. Coloradans should continue to be very cautious and wear masks in crowded indoor spaces.

Now that booster shots have been formally authorized for millions of other Americans, we’re providing answers to your key questions on COVID-19 booster shots.

What is a booster shot?

A booster shot is an additional dose of a vaccine after a person has received an earlier dose (or two in the case of COVID-19 mRNA vaccines). An extra dose “boosts” your immune system, sparking better protection against an illness.

Why do we need boosters?

It’s normal for some vaccines to wane or become slightly less effective over time. Research both by the COVID-19 vaccine makers and independent scientists is showing that the mRNA COVID-19 vaccines are waning several months after recipients get their first doses. Also, the delta variant is extremely contagious and it has caused hundreds of thousands of new infections. Because of new infections and waning effectiveness of some COVID-19 vaccines, FDA and CDC experts are recommending booster doses for many people.

What is the specific CDC advice about who should get a booster shot?

The new guidance focuses on getting boosters for older people as quickly as possible because they are most vulnerable to severe disease from a COVID-19 infection. But, anyone who is 18 and older and lives and works in a high-risk environment also can opt to get a booster dose.

Joan Hooker, 89, received her vaccine on Sunday at her church, Shorter Community AME in Denver. Who should get booster shots now?
Older adults are among the first who should receive booster shots. Joan Hooker, 90, received her first COVID-19 vaccine doses at her church, Shorter Community AME in Denver. Photo by Cyrus McCrimmon for UCHealth.

When should I get a booster?

If you received a J & J vaccine, you should get a booster shot two months or longer after your vaccine. If you received Pfizer or Moderna vaccines, you should get a third dose at least six months after you received your first vaccine doses.

Is the booster dose for Moderna different than the initial dose?

Yes. Research shows that half a dose of Moderna works well as a booster dose. So, the Moderna booster doses will now be 50 micrograms compared with 100-microgram initial doses.

Have the Pfizer and J & J booster dose amounts changed?

No. People who receive Pfizer or J & J will continue receiving the same doses that they previously did.

What’s the difference between a booster dose and a third shot for immunocompromised people?

A third shot is now the standard initial dose for immunocompromised people. These are people who have specific conditions that make it hard for them to build up antibodies to fight infections.

Immunocompromised people should get a third shot about one month after their first two doses of mRNA vaccines like Pfizer and Moderna.

Booster shots, on the other hand, are for everyone else. Healthy vaccinated people should wait two months after a J & J vaccines or six months or longer after their second dose of Moderna or Pfizer to get a booster vaccine dose.

Do I have to have a doctor’s order to get a booster shot?

No. To streamline booster doses, people can “self-attest” that they qualify for a booster dose. Also, no one needs a doctor’s order to get initial doses of COVID-19 vaccines. They are free and easy to find through hospitals, doctor’s offices, pharmacies, and at some mass vaccination clinics. Learn more about vaccine locations in Colorado.

How much do booster doses cost?

Booster doses are free, just like the initial COVID-19 vaccine doses.

Can I get a flu shot at the same time I get my booster shot?

It’s safe to get flu and COVID-19 vaccines or booster shots at the same time. But, some vaccine clinics only offer COVID-19 vaccines. You may need to schedule a flu shot separately. Please check with your doctor.

Health experts are encouraging people to get both COVID-19 vaccines and flu shots as soon as possible since we may have an early flu season and the U.S. might face a “twindemic” of infectious diseases this fall and winter.

Is it true that the Moderna vaccine is staying effective longer than the Pfizer vaccine?

Yes. Research like this new study in the New England Journal of Medicine is showing that both the Pfizer and Moderna vaccines are highly effective and very safe. It’s also common for some vaccines to diminish in their effectiveness over time. The Pfizer vaccine seems to be waning (or becoming somewhat less effective) more quickly than the Moderna vaccine.

According to new data from the CDC, vaccine effectiveness in preventing hospitalizations for COVID-19 was highest for people who received Moderna vaccines — 93% — compared with efficacy rates of 88% for people who had received Pfizer vaccines and 71% for those who had received the Johnson & Johnson vaccine.

What should people who received the single-dose Johnson & Johnson vaccine do?

About 15 million people in the U.S. received J & J vaccines, far fewer those who have received Moderna and Pfizer vaccines. J & J recipients should get a second vaccine two or more months after they got their J & J vaccine. People who received J & J may stick with that brand or they can opt to get a single dose of a Pfizer or Moderna vaccine.

Are there enough vaccines available in the U.S. for people to get both their initial doses of vaccines and their booster doses?

Yes. CDC health experts say that vaccines are plentiful. So, supply is not a problem. Get your initial vaccines as soon as possible and feel free to get a booster dose if you are eligible.

Who is considered immunocompromised?

  • Cancer patients.
  • Organ and stem cell transplant patients.
  • People with immunodeficiencies.
  • People living with HIV.
  • Patients who are being treated with immunosuppressive medications such as chemotherapy, TNF blockers to stop inflammation tied to rheumatoid arthritis, certain biologic agents like rituximab and high-dose corticosteroids.

Are boosters recommended because of breakthrough cases, COVID-19 infections in fully-vaccinated people?

  • Increases in the number of breakthrough cases of COVID-19 have caused health experts to recommend booster shots for some people.
  • But, most people getting sick with COVID-19 now are unvaccinated. And, an overwhelming majority of hospitalized COVID-19 patients have not been vaccinated.
  • Some immunocompromised people have been getting COVID-19 even if they are fully vaccinated. That’s because their bodies are unable to create the same number of antibodies as healthy people, and thus, they cannot mount the same defense against COVID-19.
  • In particular, people with cancer, rheumatoid arthritis, lupus and patients who have had organ or bone marrow transplants and those who are taking immunosuppressive medications have not been able to build up the same level of antibodies to COVID-19 as people without underlying health conditions.

How long are coronavirus vaccines effective?

Both the Moderna and the Pfizer vaccines — which account for more than 95% of U.S. vaccinations so far — remain highly effective for at least six months after people receive their second dose. The efficacy data is based on studies of how clinical trial participants have fared over time. The efficacy has declined slightly over the summer and fall, both because of the delta variant and the waning effect.

Should I stick with the same vaccine brand that I initially received when I get my booster shot?

People who are getting boosters can go with their personal presence. If you received Pfizer or Moderna and you want to stick with your original brand, you may do so. But, if you want to bump up your immunities with a different type or brand of vaccine, you are welcome to do so. A National Institutes of Health study that included a small number of people found that mixing and matching vaccine types helped increase immunities to the virus that causes COVID-19.

What are the side effects of the third dose?

So far side effects for boosters are similar to those that people experienced when they got their first two doses.

Individuals may experience a sore arm, headache, muscle aches, a low-grade fever or feel tired. These side effects typically last fewer than three days. Experts from Pfizer told FDA and CDC officials during recent testimony that many people receiving booster doses have experienced fewer side effects after third doses than they did with their second dose.

Who should skip booster doses?

Young, fully-vaccinated, healthy people probably don’t need booster doses because the vaccines are working very well to protect them from severe infections, hospitalizations and death from COVID-19, according to CDC experts.

Because the vaccines are holding up so well for young, healthy people, some infectious disease experts were hesitant to recommend booster doses for all adults.

In addition, in very rare cases, young men who have been vaccinated have experienced heart issues known as myocarditis. Due to this very rare vaccine side effect, some younger men, ages 18 to 30, may decide to skip booster doses.

Are people in other countries getting booster doses?

Yes. Israel has led the way. In Israel, older adults began getting booster doses in the early summer and now, anyone who is 12 or older can get a booster dose. Other countries like the United Kingdom and Germany also are offering booster doses.

Is there a test to determine how strong your immunity is against COVID-19?

Yes, there are antibody tests. But, doctors do not recommend antibody testing outside of clinical trials. The best way to stay healthy is to get your primary COVID-19 vaccines as soon as possible, then to get a booster dose if you qualify or fall into one of the recommended groups.

If I had COVID-19 already, do I still need vaccines?

Yes. Studies like this one are finding that vaccines are even more protective than natural antibodies. And, people can get COVID-19 after having previously had it. So, it’s best to get fully vaccinated.

Are antibodies from vaccines or previous infections the only mechanisms in our body that are fighting COVID-19 infections?

No. Researchers are finding that antibodies from vaccines team up with natural “memory” cells in our bodies. These are known as “B” and “T” cells.  CDC researchers estimate that antibodies play a majority role in fighting COVID-19 infections, but “B” and “T” cells are also crucial.

Erin Emery is a co-author of this article.

Editor’s Note: During the pandemic, the Colorado Times Recorder will occasionally post articles, like this one, from UCHealth Today, which is published by UCHeatlh, the hospital associated with the University of Colorado School of Medicine. Our goal is to provide as many people as possible with accurate information about the virus and related topics.