July 12, 2022
Covid booster doses are more effective in people with hematologic malignancies — or blood cancers including leukaemia, lymphoma, and multiple myeloma and improves their antibody levels than initial shots, finds a study.
People with blood cancers have an impaired immune system due to their disease and its treatment, which increases their risk of severe Covid-19 infection and experiencing a reduced response to Covid-19 vaccination.
The study, published in the peer-reviewed journal CANCER, showed that less than half of patients with hematologic malignancies mounted detectable antibodies after initial Covid vaccination, but 56 per cent of ‘nonresponders’ produced antibodies after receiving a booster dose.
“Our findings build on the wealth of literature showing that patients with hematologic malignancies have an impaired response to Covid vaccination. Importantly, we show that many of these patients who did not respond initially will in fact have a response to booster vaccination,” said Thomas Ollila, from the Brown University in the US.
For the study, researchers retrospectively analysed antibody responses to initial and booster Covid-19 vaccination in 378 patients with hematologic malignancies.
Anti-SARS-CoV-2 antibodies were detected in the blood of 181 patients (48 per cent) after initial vaccination. Patients with active cancer or those recently treated with an immune cell-depleting therapy were least likely to produce these antibodies. Of these, 56 per cent went on to have the antibodies after boosters.
About 33 patients developed a Covid infection, with three Covid-19-related deaths. Although there was no significant link between post-vaccination antibody response and incidence of Covid infection, no patient with antibody responses died from Covid-19.
Also, no patient who received the antibody therapy tixagevimab plus cilgavimab (packaged in Evusheld) by AstraZeneca was diagnosed with a Covid-19 infection. The antibody therapies bind to non-overlapping portions of the SARS-CoV-2 spike protein, preventing the virus from binding to and infecting cells.
“When we looked at outcomes, we found that deaths from Covid-19 in the patient population we reviewed only occurred in those with undetectable antibodies, and nobody who received prophylactic antibody therapy was diagnosed with Covid-19. This suggests to us the importance of checking antibody levels in these patients and arranging prophylactic antibody therapy,” Ollila said.
Ollila encouraged providing booster vaccines for patients and prioritising prophylactic antibody therapy when indicated. “This is real world evidence that these actions can save lives,” he said.