How well do COVID-19 vaccines work for those with chronic lymphocytic leukemia (CLL)?
What we currently know

March 2022

If you have CLL, your immune system may be weakened by the disease and from the effects of treatments. This puts you at increased risk when it comes to COVID-19. As a result, you probably have a lot of questions about:

  • Your immune system response to the COVID-19 vaccine
  • Your best time to receive the vaccine and booster

Several studies have shown increased rates of complications after COVID-19 infection in people with CLL. The COVID-19 vaccines offer potential protection but there are concerns about how effective the vaccine is for people with CLL.

Recent study data

There are several factors that affect how well people with CLL respond to COVID-19 vaccines. Researchers found the best responses to the vaccine are:

  • in younger patients (aged ≤65 years)
  • in female subjects
  • with favourable disease-related factors (mutated IGHV, β2-microglobulin ≤3.5 mg/L, and early disease stage)
  • during lack of active treatment (treatment naive or off-therapy, including ≥12 months from the last anti-CD20 therapy at the time of vaccination)
  • in higher serum immunoglobulin levels at time of vaccination

On the other hand, there are multiple reasons for poor response to a COVID-19 vaccination. Antibody response against COVID-19 was detected in only 39% of the people with CLL. However, antibody responses increased after the second vaccine.

Studies show that where a person is in their CLL treatment affects their response rate. Researchers found a:

  • 16% response rate in people in active treatment
  • 79% response rate in people who had received prior treatment and were in remission
  • 94% response rate in people who completed treatment >12 months ago
  • 16% response rate in people receiving BTK inhibitors
  • 14% response rate in people receiving Bcl2 inhibitor venetoclax
  • no response was seen in all people who received anti-CD20 antibodies in combination with targeted agents or chemotherapy within the last 12 months.
  • 55% response rate in people who had never received a treatment

CLL treatment and timing of vaccination

The type of therapy likely has an impact on the timing of a COVID vaccination and booster dose. Although some treatment options are administered as a time-limited regimen, some others, such as continuous treatment with BTK inhibitors, are not.

It isn’t yet clear how long BTK inhibitor or other continuously administered CLL therapy should be interrupted in order to achieve a better response to COVID-19 vaccines. It is important to consult your healthcare team to develop the best treatment plan. Keep in mind that if you have been on anti-CD20 therapy in the last 12 months before vaccination, you may fail to produce antibodies.

These findings are important as they might suggest that an added booster dose could be considered for people with CLL who have completed therapy and previously did not respond to a COVID-19 vaccine. Further studies are needed to determine the exact timing of an added booster.

The key points

Before starting therapy, people with CLL should receive all relevant vaccinations and this also appears to be true for COVID-19 vaccines.. Notably, people with CLL who have never been treated had a better antibody response to the vaccine than those in active treatment.

In general, the vaccine is well-tolerated. Talk to your healthcare team to get your vaccination as soon as indicated.

For people who are still untreated, or will be treated shortly, a pre-therapy vaccination may be recommended, although responses might also be affected by the immunosuppression that accompanies the disease itself.

In summary, the response to COVID-19 vaccine is lower in people with CLL. Depending on your situation, you may want to continuously evaluate other measures to keep yourself protected, including social distancing and wearing a mask. It is strongly recommended that anyone with whom you are in close contact should be vaccinated.