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Experts: Blood Cancer Patients Should Receive a Booster COVID-19 Vaccine

An older adult woman with a scarf on her head looking at a male healthcare worker's hand, which is cleaning a spot on her arm to deliver a vaccine.

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Key Takeaways

  • Certain blood cancer treatments may cause patients to have a dulled reaction to the COVID-19 vaccine.
  • A booster dose of the COVID-19 vaccine may help blood cancer patients who had no response, or an inadequate response, to their initial dose of the vaccine.
  • Blood cancer patients should not stop their treatment before getting a COVID-19 vaccine unless their doctor tells them to.


The Leukemia & Lymphoma Society (LLS) is encouraging blood cancer patients who received either the Pfizer or Moderna mRNA COVID-19 vaccine to get a third dose.

The LLS’s recommendation aligns with the Centers for Disease Control and Prevention’s (CDC) booster guidelines for people who are moderately-to-severely immunocompromised.

Why Patients Need Boosters

Data collected by the LLS showed that about one in four blood cancer patients will not form detectable antibodies to COVID-19 after receiving two doses of the Pfizer and Moderna vaccines.

The reason for the dulled response is because the medications that are used to treat blood cancers often suppress the immune system, which in turn weakens its response to the vaccine.

In a press release on September 13, Lee Greenberger PhD, chief scientific officer for the LLS, said that “antibodies tell us that a patient has responded to vaccination—and that is a positive finding, but vaccine experts are still working to determine exactly what antibody level is needed to protect against COVID-19 infection or its worst outcomes.”

If You Got the J&J Vaccine

The CDC’s recommendations only apply to people who received either the Pfizer or Moderna vaccines.

Until more data is available, the LLS is asking patients to speak to their cancer care providers about a second dose of the Johnson & Johnson vaccine.

LLS investigators published follow-up research in the journal Cancer Cell showing that 55% of the patients who had no response to the first two doses of the Pfizer or Moderna vaccines did develop antibodies after receiving a third dose.

Furthermore, all of the patients that originally developed some antibodies against COVID-19 after receiving the first two vaccines had an even higher level of antibodies after the third dose.

However, Gwen Nichols, MD, the chief medical officer for LLS and one of the study’s authors, says that it is not yet known what level of antibodies provides full protection against COVID-19; still, any gain in antibodies is beneficial.

B-Cells and Vaccine Response

Non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia (CLL) damage and deplete healthy B lymphocytes, which play a key role in helping the body develop antibodies against the COVID virus.

The depletion of these cells is why patients with NHL and CLL are most likely to have an inadequate immune response to the COVID vaccine.

Anti-CD20 and BTK Inhibitor Therapies

The researchers discovered that two classifications of medications that are used in complement to blood cancer treatment (including to treat NHL and CLL) can diminish a person’s response to the COVID-19 vaccine.

  • CD20 monoclonal antibodies, or anti-CD20 antibodies. These medications are designed to attack CD20, a unique protein on the surface of B lymphocyte cells. The most common anti-CD20 antibody is rituximab (Rituxan). In addition to NHL and CLL, rituximab can also treat rheumatoid arthritis (RA) and multiple sclerosis (MS).
  • Bruton tyrosine kinase (BTK) inhibitors. BTK inhibitors stop an enzyme that signals B lymphocytes to reproduce (Bruton tyrosine kinase or BTK). Stopping reproduction of the B lymphocytes prevents them from proliferating, which in turn can slow the progression of NHL and CLL. Three BTK inhibitors are currently approved: ibrutinib (Imbruvica), acalabrutinib (Calquence), and zanubrutinib (Brukinsa).

Nichols highlights that neither class of medications selectively targets diseased B lymphocytes; both therapies have a broad effect on all B lymphocytes. Therefore, anyone taking these medications will have fewer healthy B lymphocytes than people who do not take them.

What This Means For You

If you’re taking any of these medications, you might wonder if you should stop taking them to help your body respond better to the COVID vaccine.

Nichols emphasizes that patients should not stop their treatment without talking to their healthcare team.

“Nothing in this paper suggests that you should stop your cancer therapy in order to get an antibody response to the vaccinations,” says Nichols. “If stop your medication and your lymphoma comes back, you’re in equally bad shape, so you should not stop it without talking to your doctor.”

When to Get a Booster

The CDC is advising that patients receive the third dose at least four weeks after getting their second dose of one of the mRNA COVID vaccines.

Nichols says that patients who had COVID-19 antibody testing showing that they have developed immunity in response to the vaccine can wait until six to eight months after their second dose to get a booster shot.

Take Precautions Even If You're Vaccinated

LLS is urging all blood cancer patients to continue taking COVID precautions regardless of their vaccination status.

Patients should keep wearing a face mask, practicing proper hand washing, social distancing, and avoiding poorly ventilated indoor spaces.

“Not everybody knows whether they made antibodies, but I don’t think there’s any harm in getting it sooner,” says Nichols. “If you know that you had no antibodies please get it as soon as you can, but if you made antibodies, you should get it at six to eight months because it will last longer.”

Future Research

The LLS Patient Registry has collected data on more than 11,000 blood cancer patients. Nichols acknowledges that this is "really a small number of patients" and that it is "a preliminary study," but it's still a good start.

As more patients contribute to the registry, researchers will gain a better understanding of how blood cancer patients respond to vaccines and will be able to make recommendations that will improve care for all people with blood cancer.

“The good news is, a lot of the patients are getting boosters and are giving us information about the boosters," says Nichols. "So we should have data on hundreds of more patients over the next few months.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention (CDC). COVID-19 vaccines for moderately to severely immunocompromised people. Updated September 2, 2021.

  2. Greenberger LM, Saltzman LA, Senefeld JW, Johnson PW, DeGennaro LJ, Nichols GL. Antibody response to SARS-CoV-2 vaccines in patients with hematologic malignanciesCancer Cell. 2021;39(8):1031-1033. doi:10.1016/j.ccell.2021.07.012

  3. Greenberger LM, Saltzman LA, Senefeld JW, Johnson PW, DeGennaro LJ, Nichols GL. Anti-spike antibody response to SARS-CoV-2 booster vaccination in patients with B cell-derived hematologic malignancies. Cancer Cell. Published online September 7, 2021. doi:10.1016/j.ccell.2021.09.001.