A new study has found that certain types of cancers -- particularly those that affect the blood, bone marrow, or lymph nodes -- could render COVID-19 vaccines significantly less effective.
The results of an analysis of University of Pittsburgh Medical Center (UPMC) patients found that people with these cancers are at a higher risk of COVID-19 vaccine failure. The risk was particularly elevated among patients with chronic lymphocytic leukemia (CLL).
The researchers said these patients, as well as those who interact with them, should get vaccinated as soon as possible and keep practicing pandemic health protocols. Even after getting vaccinated, the researchers recommend that consumers continue to wear masks and practice social distancing.
"As we see more national guidance allowing for unmasked gatherings among vaccinated people, clinicians should counsel their immunocompromised patients about the possibility that COVID-19 vaccines may not fully protect them against SARS-CoV-2," said senior author Dr. Ghady Haidar, a UPMC transplant infectious diseases physician, in a news release.
‘Equivalent of a coin flip’
The study, which has been published in the preprint server medRxiv, involved 67 patients with hematologic malignancies who had been vaccinated with either the Pfizer or Moderna COVID-19 vaccines.
The researchers tested the patients’ blood three weeks after the final dose and found that more than 46 percent of the patients had not generated COVID-19 antibodies. Only 3 of the 13 patients with chronic lymphocytic leukemia made antibodies, even though 70 percent weren't undergoing any cancer therapy.
Haidar said the analysis showed that the antibody response to vaccines among those with hematologic malignancies are “the equivalent of a coin flip.” He added that a negative antibody test doesn’t necessarily mean that the patient doesn’t have any protection from the virus. Still, the researchers said the lack of response was “strikingly low.”
“We're still working to determine why people with hematologic malignancies -- particularly those with CLL -- have a lower antibody response and if this low response also extends to patients with solid tumors," said Dr. Mounzer Agha, a hematologist at UPMC's Hillman Cancer Center.
While more research is being carried out, these patients should “be aware of their continued risk and to seek prompt medical attention if they have COVID-19 symptoms, even after vaccination," Agha said.
"They may benefit from outpatient treatments, such as monoclonal antibodies, before the illness becomes severe,” Agha added.