Throughout the COVID-19 pandemic, people with compromised immune systems have been cautioned that they have a higher chance of severe illness if they contract the virus.

While vaccination paved the way for something of a return-to-normal for much of the world, new data suggests that some people — like those with leukemia — still need to take certain precautions to prevent serious illness.

There have been several vaccines developed to fight COVID-19 over the last few months. Because these vaccines are so new, there’s been little data on how well they work among people with various health conditions.

Over the last several months, a number of studies have been published that take a closer look at the response in people with blood cancers, including chronic lymphocytic leukemia (CLL).

People with CLL and other types of leukemia already carry a higher chance of severe illness or even mortality if they develop COVID-19. This is because cancer impairs the immune system.

As vaccines against the virus were developed, they were tested in generally healthy adults. As more groups become vaccinated, there’s more evidence on special populations, like people with compromised immune systems.

Recent study data

B cells are critical to fighting COVID-19. These are the immune cells that can neutralize the virus and help produce antibodies. People with CLL are at an increased risk when it comes to COVID-19 because B cells are the most affected by this specific type of blood cancer.

A 2021 study found that people with CLL who were vaccinated with Pfizer’s mRNA COVID-19 vaccine had an antibody response rate of 39.5 percent. In generally healthy adults, this rate is around 90 percent.

Individual response rates varied among people with CLL based on their disease progression and treatment. Response rates in different groups of people with CLL included:

  • 79.2 percent response rate in people in clinical remission from CLL
  • 55.2 percent response rate in people with CLL who hadn’t yet received treatment
  • 16 percent in people with CLL who were undergoing treatment at the time of COVID vaccination

While response rates were generally low in people with CLL receiving treatment at the time of vaccination, these rates were further impacted by the type of treatment.

People treated with Bruton’s tyrosine kinase (BTK) inhibitors had a 16 percent response rate to the vaccine, while those treated with venetoclax ± anti-CD20 antibody had just a 13.6 percent response rate. No one who was treated with anti-CD20 antibodies in the year before COVID-19 vaccination had any immune response, according to the study.

There were other factors that affected how well people with CLL responded to the vaccine, too. Researchers found that the people with CLL who had the best responses to the vaccine:

  • were younger in age
  • were female
  • weren’t receiving active treatment for CLL
  • had immunoglobulin G levels of 550 mg/dL or higher
  • had immunoglobulin M levels of 40 mg/dL or higher

While about a quarter of all people with CLL who were fully vaccinated against COVID-19 didn’t have immune responses to the virus, leading cancer organizations are still recommending that people with CLL receive some type of COVID vaccine.

The Leukemia and Lymphoma Society suggests people with leukemias and lymphomas should “get vaccinated, act unvaccinated.” This means that while the vaccine may be helpful, it may not work at its full potential in people with blood cancers.

Despite the fact that people with certain cancers may not get the highest levels of protection from the vaccine, even some protection is better than none.

At this time, extensive research hasn’t been done to study the effect of the various COVID-19 vaccines in specific populations. However, early data on people with blood cancers suggest the vaccine is safe.

While it may not be as effective as in people without blood cancers, the vaccine can offer at least some protection against COVID-19. The Leukemia and Lymphoma Society stresses the dangers of a COVID-19 infection for people with CLL and supports vaccination in people with this condition.

Vaccines from Pfizer, Moderna, and Johnson & Johnson are all believed to be safe for people with CLL, unless you have an allergy or other contraindication to the vaccine.

Although vaccination can offer some protection against COVID-19 for people with CLL, experts suggest that anyone with blood cancers — especially those undergoing active treatment — continue to take precautions, even after being fully vaccinated. Precautions include:

If you live in places with a high prevalence of COVID-19 transmission, your treatments may be modified or delayed to protect against infection. These decisions should be made by you and your doctor based on your location and your specific condition and risk factors.

CLL is a type of blood cancer that can affect your immune system’s ability to fight off illnesses. Treatments for this cancer can further decrease your immune system’s functioning, leading to lower response for several types of vaccines, including the COVID-19 vaccine.

The COVID-19 vaccine is recommended for anyone with CLL, as it still offers a level of protection. If you have CLL, you should continue to take precautions like wearing a mask and avoiding crowds, even after you’ve been fully vaccinated.

If you still have questions or concerns about whether the vaccine is right for you, bring this up at your next medical appointment to find out what might work best for you.