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tempered hope in covid vax study of cancer patients
while 94 per cent of 131 patients produced the antibodies needed to fight the virus after the second dose, seven remained unprotected.
jul 5 2021
3 minute read
empty vials of the pfizer-biontech vaccine are seen at the michener institute, in toronto.
carlos osorio/reuters
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reuters
the vast majority of cancer patients who received two doses of an mrna vaccine developed a robust immune response within a month of their second jab, according to an international study. the encouraging findings were tempered by concerns about the remaining participants who developed no response at all.
the u.s. and swiss study, published in the journal cancer cell , found that while 94 per cent of 131 patients produced the antibodies needed to fight covid-19 within a month of their second dose, seven high-risk individuals remained unprotected. “we could not find any antibodies against the virus in those patients,” said dimpy p. shah , corresponding author of the study at the mays cancer center in san antonio. “that has implications for the future. should we provide a third dose of vaccine after cancer therapy has been completed in certain high-risk patients?”
cancer patients have been a particular concern to doctors throughout the pandemic because undergoing chemotherapy or other gruelling treatments can compromise the immune system and leave a person more vulnerable to the virus. while it’s encouraging that the vast majority of participants developed antibodies to the virus, it was at levels much lower than the rest of the population. “how that relates to protection against covid-19, we don’t know yet,” shah said.
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within six months of their second jab, none of the high-risk patients undergoing a monoclonal cancer therapy called rituximab produced any of the antibodies needed to fight the virus.
“with other vaccines and infections, patients with cancer have been shown not to develop as robust an immune response as the general population,” said ruben mesa, study senior coauthor and executive director of the mays cancer center. “it made sense, therefore, to hypothesize that certain high-risk groups of patients do not have antibody response to covid-19 vaccine.”
the specific type of cancer appeared to play a role in the immune system’s response. “patients with hematological malignancies, such as myeloma and hodgkin lymphoma, were less likely to respond to vaccination than those with solid tumours,” said pankil k. shah, co-lead author of the study, also from the mays cancer center.
the study — which did not include the delta variant or any other covid mutations — had a few limitations researchers are hopeful will be addressed by future research, including the size and diversity of its sample group. participants had a median age of 63 and were 80 per cent non-hispanic white, 18 per cent hispanic and two per cent black. just over 80 per cent had solid cancers, the remainder had hematological malignancies — cancers that affect the blood, bone marrow and lymph nodes.
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“we recommend that future studies be done in black, asian and hispanic patients, as well, to see if there are any differences in vaccination immune response,” mesa said.
the study was one of the few that included months of observation after the second dose of vaccines, allowing it to conclude the second jab is vital for a certain group of people. “we observed a significant difference in response when two doses were given,” shah said. “at least for patients with cancer, two doses are very important for robust antibody response.”
those currently fighting cancer, particularly people receiving anti-cd20 antibodies, should continue to take every public safety precaution — even after inoculation, shah said. “they still need to have that awareness that they could potentially be at risk because their body has not responded to vaccination.”
dave yasvinski is a writer with healthing.ca
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