People with blood cancer, who already are particularly vulnerable to COVID-19, do not develop strong immunity after vaccination and need additional layers of protection, according to led by UCLA Health.
Antoni Ribas, MD, director of the at the Jonsson Comprehensive Cancer Center, said of patients with common blood cancers, such as chronic lymphocytic leukemia (CLL) and non-Hodgkins lymphoma, only 40% to 70% produced antibodies to fight COVID-19 after vaccination. By comparison, 98% to 100% of healthy people developed antibodies.
Blood cancer patients also responded poorly to third doses of the COVID-19 vaccine that were approved in August for those who are immunocompromised.
“The data suggest that the major issue is the cancer treatment,” said Dr. Ribas, who was the lead author of the study. “These treatments are life-saving for these patients. That’s why the rest of the article is about how to provide protection to patients.”
The paper was published Sept. 15 in the journal Blood Cancer Discovery.
Dr. Ribas, professor of medicine at the , said the findings build on his earlier research published in December in that analyzed COVID-19 outcomes in people with cancer before vaccines were widely available.
The study concluded that, globally, people with cancer were more likely to suffer severe illness or die because of their limited abilities to naturally mount an antibody response to the virus.
“Patients with cancer had a doubling risk of death and the highest risk of death was blood malignancies,” Dr. Ribas said. “They had higher death rates so it makes sense to study the vaccine response in them.”
More vulnerable
People with blood cancer are more vulnerable to COVID-19 because of the nature of their cancer, which most often starts in the immune system blood cells, and because of their cancer treatment, which further damages immune cells.
“Many blood cancers are cancers of the lymphocytes, which are the white blood cells that make up the immune system,” Dr. Ribas said. “In many of the lymphocyte blood cancers, the normal lymphocytes do not work as well and do not make antibodies as well.”
Not only does the cancer impair the ability to fight infection, but treatments such as chemotherapy, bone marrow transplants and targeted drugs kill the cells that would normally allow patients to develop immunity from the vaccine.
The research found that immune response was weakest among those actively undergoing treatment, Dr. Ribas said.
“The ones that are receiving treatments that decrease the function of the cells that make antibodies are the ones that are not responding to the vaccine, which is logical,” Dr. Ribas said.
Dr. Ribas said doctors already knew that people with blood cancer were less likely to develop immunity after other types of vaccination. The team of cancer immunology and hematology-oncology experts from across the country analyzed 22 clinical papers on response to COVID-19 vaccines in people with blood cancer.
Despite the reduced immune response, Dr. Ribas said it’s essential for patients to undergo treatment during the pandemic and to get vaccinated.
“It’s better to be vaccinated even if they are on treatment than to not be vaccinated,” he said. “Any added protection from the vaccine, even if it’s much lower than in normal persons, it would help them fight the virus.”
In August, the Centers for Disease Control and Prevention recommended that people who are immunocompromised, including patients with blood cancer, receive a third COVID-19 shot.
Dr. Ribas said among patients with blood cancer who did not produce antibodies after completing their first two shots, 50% continued to have no response after a third shot.
Added protection
Dr. Ribas said more research is needed to determine if people with blood cancer need more frequent doses, larger doses or a combination of different types of COVID-19 vaccines for greater effectiveness.
In the meantime, a number of measures can help shield them from the risk of contracting the coronavirus.
People with blood cancer should have their antibody levels checked after vaccination. All health care workers around them, as well as family members, should be vaccinated. Dr. Ribas said masking, social distancing and frequent COVID-19 testing for the vaccinated are also necessary.
“My simple way to explain this is the virus has no legs – we humans give legs to the virus,” he said. “If there are people, like patients with blood cancers, that have less protection to the virus, somebody with legs will bring the virus to them. That’s what we have to prevent.”
People with blood cancer who test positive should immediately receive treatment, such as monoclonal antibodies or convalescent plasma.
“What’s missing in them is the antibody response, so getting antibody therapy would make a lot of sense,” Dr. Ribas said.
Broader consequences
According to the Leukemia and Lymphoma Society, an estimated 186,000 Americans will be diagnosed with a blood cancer this year, accounting for nearly 10% of new cancer cases.
Dr. Ribas said better protection for people with blood cancer and other immunocompromised patients is crucial to ending the pandemic, even if herd immunity is achieved by the population at large.
“If the body cannot mount a response to the virus, then it keeps growing and growing,” he said. “Every time it grows it can make errors, which are mutations that can lead to a variant. If there’s a lot of virus growing in a person for a long time, the chance for a new variant to appear is much higher.”
New strains of the virus can eventually pose a threat to those who are fully vaccinated.
“At some point, those variants may go back and infect the previously protected population because the virus has evolved so much,” he said.
Learn more about research and patient care at UCLA’s .
Courtney Perkes is the author of this article.
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