People with chronic lymphocytic leukemia (CLL) may be at higher risk of severe illness from COVID-19. While the COVID-19 vaccines may not be as effective in these individuals, health experts still advise that the majority of people with CLL get the vaccine as soon as possible because the benefits outweigh any potential risks.

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CLL is a type of cancer that affects the lymphocytes, which are a type of white blood cell. It is the most common type of leukemia in adults in the United States. Both CLL and its treatment options can weaken the immune system.

As a result, people with CLL are at a higher risk of severe illness from COVID-19, and vaccines may not offer complete protection again the virus.

However, health experts recommend that people living with cancer receive all their COVID-19 shots, including third doses and boosters, as soon as possible. This advice is applicable to cancer survivors and those currently undergoing cancer treatment as long as there is no contraindication for any components of the vaccine.

The COVID-19 vaccines are safe and effective for most people with blood cancers and can help protect against SARS-CoV-2 infection. Health experts believe that the benefit of these vaccines outweighs the potential risks for the majority of those with CLL.

In addition to receiving vaccines, people with CLL and their caregivers should also continue taking additional precautions, such as hand washing and mask wearing.

In this article, we look at the safety and efficacy of the COVID-19 vaccines for people with CLL, any considerations to make when getting a vaccine, and other precautions people can take.

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The Leukemia and Lymphoma Society (LLS) recommends that all people with blood cancers get the COVID-19 vaccine unless, in rare cases, people have a contraindication to the vaccine.

The LLS states that the COVID-19 vaccines are safe and effective for the majority of people with blood cancers. People with CLL are at higher risk of severe symptoms from COVID-19, which the vaccines offer protection against. Therefore, it is advisable for them to receive the vaccine to reduce any potential risks.

While some evidence suggests that people living with CLL may have a limited immune response, health experts still encourage those with blood cancers to follow guidelines for recommended COVID-19 vaccine doses as soon as they are eligible. Additionally, it is advisable to continue preventive actions despite the relaxation of local regulations.

A 2021 systematic review and meta-analysis notes that individuals with CLL may fail to develop a robust antibody response following vaccination. This is likely due to how CLL impacts the immune system.

While further research is still necessary, some evidence suggests that certain CLL treatments may also impact the immune response. However, research indicates that further doses may offer improved protection.

A 2021 study by the LLS found that COVID-19 vaccines might not produce detectable antibodies in people with certain types of blood cancer. The study looked at the effects of COVID-19 vaccination in more than 1,400 people with different types of blood cancers.

A fortnight after receiving the second dose of an mRNA vaccine, researchers measured the antibodies present in the participants. The study found that people with CLL are most likely to be seronegative, which means antibodies against SARS-CoV-2 were not detectable in their blood.

Over 36% of people with CLL were seronegative, and 3 in 10 of those had not received cancer therapy within the previous 2 years. This suggests that CLL, rather than cancer treatment, may affect the function of B cells, which produce antibodies in response to vaccines.

However, certain treatments may also affect antibody production. Seronegative rates were higher in people given drugs such as BTK inhibitors. Treatment with anti-C20 antibodies within the past 12 months may also reduce the response to COVID-19 vaccines.

As a result, a doctor may suggest pausing certain treatments if the condition is under control, or waiting until treatment is complete, to try to maximize the immune response to vaccination.

A 2022 study adds that in individuals who were seronegative after a second dose, almost 1 in 4 responded to a third dose of the vaccine. These findings suggest that a third dose can offer protection even in more immunosuppressed people.

According to a 2021 study, people with CLL are at higher risk of complications and life threatening illnesses from COVID-19. The study states that despite a lower rate of antibody production in people with CLL, vaccinations are still the best protection available against COVID-19 and remain a priority for people with cancer.

As such, while a doctor may assess the benefit of the vaccines on a case-by-case basis, health experts generally recommend the vaccine for those with CLL.

People may need to discuss COVID-19 vaccination with their doctor, as certain CLL treatments may affect how effective the vaccines are. Research suggests the most effective time for vaccination is straight after a CLL diagnosis, in the early stages of the disease, or before receiving any treatment for CLL.

As with the general population, people with CLL may experience some side effects from COVID-19 vaccination. A 2021 survey of 4,505 people with blood cancer looked at the side effects of COVID-19 vaccinations. Most people had Pfizer or Moderna vaccines, with a small percentage receiving Johnson & Johnson or AstraZeneca.

The most common side effects that people reported include:

  • sore arm and pain at the injection site
  • fatigue
  • headache
  • muscle aches
  • feeling unwell
  • fever

Some people experienced no negative side effects, and allergic reactions were rare. Less commonly, people experienced:

  • chills
  • nausea
  • swollen lymph nodes

People can talk to a healthcare professional about getting a COVID-19 vaccine. The Centers for Disease Control and Prevention (CDC) list ways of getting the vaccine here.

People will need at least two doses of a COVID-19 vaccine as this increases its effectiveness. Leaving a gap of 10–12 weeks between the first and second doses of mRNA and adenovirus vaccines may also increase the response rate.

The LLS advises all people with blood cancer to receive the full set of doses that each vaccine requires, as well as booster doses.

People with compromised immune systems can receive three doses of an mRNA vaccine, as well as a booster dose 3 months afterward. People who are receiving the Johnson & Johnson vaccine can receive a second dose with an mRNA vaccine 28 days after the first, and then a booster mRNA vaccine 2 months following the second dose.

The LLS suggests that all people with blood cancers receive COVID-19 vaccinations but continue to act as though they have not taken a vaccine. This means that even once people are fully vaccinated, they will continue to take protective measures against COVID-19.

This is because vaccination may not provide complete protection, and people could still be at risk of infection.

Additional protective measures can include:

  • wearing masks in public places
  • social distancing
  • regular hand washing
  • avoiding crowds
  • avoiding indoor spaces with poor ventilation
  • considering any travel carefully

People will need to contact a doctor straight away if they think they have had exposure to COVID-19. People can receive monoclonal antibody treatment, which can help to treat COVID-19 infection in people at high risk of severe illness.

COVID-19 vaccines are safe for people with CLL, and health experts generally advise that people receive the vaccine as soon as they are eligible. People with CLL are at higher risk of severe illness from COVID-19, and the vaccines can help to protect against SARS-CoV-2.

Some CLL treatments may affect how effective the vaccine is, so people can discuss the timing of their medication and vaccination schedule with their doctor.

Full vaccination may not offer complete protection for people with CLL, so it is advisable for people to continue taking additional precautions such as mask wearing, physical distancing, and hand washing.