• To improve protection against COVID-19, the Centers for Disease Control and Prevention (CDC) has approved a second COVID-19 booster shot for adults aged 50 and older and all people with immunocompromising conditions.
• Most people with leukemia (over the age of 12) are eligible to receive a second booster shot. People receiving stem cell transplants or chimeric antigen receptor T-cell (CAR-T) therapy should wait at least three months after treatment and talk to their oncologist about any questions.
• With the omicron variant waning and COVID-19 control measures ending, now is an ideal time to get up-to-date on vaccinations before new variants arise.

Health officials at the CDC and the U.S. Food and Drug Administration (FDA) have authorized a second COVID-19 booster for all adults over 50 and for people with suppressed immune systems. These people are at increased risk for severe disease and hospitalization from COVID-19, so increased protection against infection is important.

Updated public health recommendations come after researchers found that receiving an initial booster of the Moderna or Pfizer vaccine is safe and effective in preventing severe disease and hospitalization. The CDC has also found that the effectiveness of the first booster decreases over time, so a second booster is recommended to help maintain protection against COVID-19 infection.

The New Recommendation and Second Booster Eligibility

On March 29, the FDA authorized a second booster of either Pfizer or Moderna COVID-19 vaccines for certain individuals. The following people are eligible for a second booster shot at least four months after their first booster vaccine:

• Individuals aged 50 or older who received a first booster dose of the Pfizer or Moderna COVID-19 vaccine are eligible to receive a second booster dose of the Pfizer or Moderna vaccine.
• Individuals aged 12 or older with certain immunocompromising conditions who received a first booster dose of either vaccine are eligible for a second booster dose of the Pfizer vaccine.
• Individuals aged 18 or older with the same types of immunocompromising conditions who received a first booster dose of either vaccine are eligible for a second booster dose of the Moderna vaccine.

Some important details about these recommendations include:

• This fourth shot would be either the Moderna or Pfizer vaccines, not the Johnson & Johnson vaccine.
• Even if you were previously vaccinated with the Johnson & Johnson vaccine, your booster should be a Moderna or Pfizer vaccine only.
• For those who are immunocompromised and received a third dose of the primary vaccination followed by an initial booster, this booster would count as your fifth shot.

If You Have Leukemia, Are You Eligible for a Second Booster?

The Leukemia & Lymphoma Society and the American Cancer Society support COVID-19 vaccination for most people with leukemia and other types of cancer. Your eligibility for a second booster depends on your age and the status of your immune system. If you have leukemia and are over 50 years old, it’s recommended you receive a second booster at least four months after your first booster shot.

The American Cancer Society notes that people with cancer may have weakened immune systems if they:

• Are in active cancer treatment (for solid tumors or cancers of the blood, like leukemia)
• Are being actively treated with high-dose corticosteroids or other medications that can suppress the immune system
• Have received a stem cell transplant or CAR T-cell therapy within two years

People who have leukemia and have weakened immune systems and are over the age of 12 are technically eligible for a second booster, but it’s best to make that decision with your cancer care team. The COVID-19 vaccine and booster doses may not be as effective for people with weakened immune systems. However, doctors and medical experts still recommend that these people get vaccinated because they are at high risk of severe COVID-19, complications, and hospitalizations.

People with leukemia who should not get a second COVID-19 booster include:

• People currently receiving stem cell transplants
• People currently receiving CAR T-cell therapy

These people should wait at least three months after treatment to get a second booster shot, and talk to their oncologists about any concerns.

If you need help finding a location to get a second booster or any COVID-19 vaccine, visit vaccines.gov.

How Effective Is the Moderna Vaccine for Immunocompromised People?

There is promising new research about the effectiveness of COVID-19 vaccines for immunocompromised people. A recent study from Moffitt Cancer Center included people diagnosed with blood cancers like leukemia and people with solid tumors in their organs. Researchers tested levels of antibodies, the proteins the immune system makes to help destroy a target. In this case, the antibodies were to the SARS-CoV-2 virus that causes COVID-19, made in response to the Moderna COVID-19 vaccine.

Study results showed that about 90 percent of people had COVID-19 antibodies after getting a second dose of the vaccine. About 98 percent of people with solid tumors showed an antibody immune response, while nearly 85 percent of people with blood cancers responded.

The lowest antibody response — around 30 percent — was seen among people who had chronic lymphocytic leukemia or B-cell non-Hodgkin lymphoma and were receiving immunosuppressive therapy. But their response was much higher — nearly 73 percent — when they were not receiving treatment at the time of vaccination.

People who had the following treatments generally had less response to the vaccine:

• Anti-CD20 monoclonal antibodies (including rituximab, sold as Rituxan) less than six months before vaccination
• Bruton tyrosine kinase inhibitors (such as ibrutinib, sold as Imbruvica) used to treat some types of lymphoma and leukemia
• P13K inhibitors (such as idelalisib, sold as Zydelig) used to treat a variety of cancers
• Venetoclax (sold as Venclexta) used to treat leukemia and lymphoma
• CD19 CAR-T therapy used to treat leukemia, lymphoma, and multiple myeloma

People who had autologous (self) stem cell transplants in the past year or allogeneic (donor) stem cell transplants had a stronger response to the vaccine

How Effective Is the Pfizer Vaccine for Immunocompromised Individuals?

Other research has looked at the response of immunocompromised individuals to the Pfizer vaccine. The Pfizer and Moderna vaccines both use a molecule called messenger RNA (mRNA) to teach cells how to make a protein that will trigger an immune system response and help prevent a COVID-19 infection.

In one study, around 72 percent of people who were immunocompromised produced antibodies in response to the Pfizer vaccine. Another study showed immune system response in people with a wide variety of immunocompromising conditions was, on average, about 67 percent.

Study participants with some conditions were much more responsive to the Pfizer vaccine than others. For instance:

• People with HIV made antibodies in response to the Pfizer vaccine 98.7 percent of the time (similar to the general population).
• People with multiple myeloma responded nearly 80 percent of the time.
• Only 45 percent of people with kidney transplants responded to the vaccine.

A study looking at both mRNA vaccines in immunocompromised people living with HIV or solid organ transplants found the Pfizer vaccine had a similar response rate (about 94 percent) to the Moderna vaccine’s (around 92 percent).

Why These Results Matter

These research studies show us that additional doses of mRNA vaccines may be effective at increasing detectable antibodies in a similar way to the first and second doses — which could mean improved protection against COVID-19. Other research tells us that antibody levels are likely to decrease over time, so getting booster doses at recommended intervals is necessary even in vaccinated people who made antibodies after their initial shots.

Simply making antibodies does not always necessarily translate to complete immunity against COVID-19 infection. The findings from these studies are a good sign that the mRNA vaccines for COVID-19 can trigger strong responses, even from people with compromised immune systems. It’s evidence that vaccines can protect people at higher risk of severe infections.

According to the CDC, getting vaccinated is still the best way to protect yourself and others, and slow the spread of the virus. If you’re unvaccinated because you have an immunodeficiency or autoimmune disease, were being treated for cancer, or are an organ transplant recipient, this new research should give you confidence to speak with your health care provider about when a COVID-19 vaccine would be right for you.

With the CDC now recommending a second COVID vaccine booster and the omicron variant declining, now is an excellent time to get vaccinated and give your body a chance to build up immunity before a possible next wave of the pandemic. Talk to your doctor about a booster dose, or schedule a booster appointment through vaccines.gov.

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