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COVID vaccines do not work well for patients with hematologic malignancies, new data suggest.
A small study involving 67 such patients shows that nearly half did not produce antibodies and were therefore still at risk of contracting COVID-19, even though they had all received both doses of one of the new mRNA COVID vaccines (Moderna or Pfizer).
"[This] is in stark contrast with the results of phase 1 mRNA vaccine immunogenicity trials, in which robust antibody responses were seen in essentially 100% of participants," say the authors, led by Mounzer Agha, MD, director of the Mario Lemieux Center for Blood Cancers at the University of Pittsburgh Medical Center (UPMC) Hillman Cancer Center, Pittsburgh, Pennsylvania.
"Clinicians caring for patients with hematological malignancies and other immunocompromising conditions should be aware of the possibility of COVID-19 vaccine failure," they emphasize.
"It's critically important for these patients to be aware of their continued risk [for SARS-CoV-2 infection] and to seek prompt medical attention if they have COVID-19 symptoms, even after vaccination," Agha said in a statement.
The study was published online on April 9 as preprint in medRxiv and has not yet undergone peer review.
The authors analyzed responses in a group of 67 patients who had a hematologic malignancy, including chronic lymphocytic leukemia (CLL), lymphoma, and multiple myeloma. Approximately 45% of the patients were receiving therapy for their cancer at the time of vaccination; the rest were under observation.
All patients received two doses of an mRNA COVID vaccine and so were considered to be fully vaccinated.
Antibody responses for these fully vaccinated patients were then analyzed. The median duration between receipt of the second dose of the vaccine and the antibody test was 23 days.
"In total...46.3%...had a negative antibody result after vaccination and were therefore considered to be vaccine non-responders," the authors report.
The worst responses occurred in patients with CLL, of whom only 23% produced measurable antibodies to either vaccine, although approximately 70% of these patients were not receiving any form of cancer therapy at the time of vaccination.
Older patients were more likely not to have a response to either vaccine than younger patients, the investigators add.
In contrast, gender, immunoglobulin G levels, the number of days between the second dose and the measurement of antibodies, and status of cancer therapy did not differ among patients who had a response to the vaccines and those who did not.
"Our findings underscore the importance of adherence to non-pharmaceutical interventions to prevent COVID-19 in hematological malignancy patients," the authors emphasize. This is particularly important, given the fact that among patients with hematologic malignancies who become infected with SARS-CoV-2, the mortality rate is in excess of 30%.
Moreover, among such patients, viral shedding may be prolonged, often lasting several months. As such, "these patients should be advised to wear masks and observe social distancing regardless of vaccination status," the investigators advise.
As of March 2021, guidance from the Centers for Disease Control and Prevention has allowed gatherings of unmasked people who have been vaccinated and of those at low risk for COVID-19 who have not yet been vaccinated. "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," co-author Ghady Haidar, MD, assistant professor of medicine at the UPMC, said in a statement.
"Our results show that the odds of the vaccine producing an antibody response in people with hematologic malignancies are the equivalent of a coin flip," he reemphasized.
The authors have disclosed no relevant financial relationships.
medRxiv. Published online April 7, 2021. Full text
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Cite this: COVID-19 Vaccine Failure in Patients With Blood Cancers - Medscape - Apr 13, 2021.