ABSTRACT
Coronavirus disease 2019 (COVID-19) vaccine development and administration have become global priorities since the beginning of the pandemic, particularly for special populations at higher risk of complications and mortality, such as patients with haematologic and solid organ malignancies. This review aims to summarise the current data for COVID-19 vaccine efficacy in patients with cancer, suggest priority areas for future research and look at potential disparities at a global level. Although patients diagnosed with or receiving therapy for cancer were excluded from the initial vaccine trials, emerging evidence now supports vaccine safety with potentially diminished immune response in this group. Several studies that evaluated antibody response to COVID-19 vaccination found that patients with solid malignancies had lower serologic response rates compared to healthy controls, but better than patients with haematologic malignancies, who had the lowest seroconversion rates and antibody titres. As anticipated, poor serologic responses have been particularly observed among patients receiving B-cell depleting therapies. The data on cellular response are scarce and conflicting since not all studies have showed a difference between patients with malignancies and healthy subjects. Several questions concerning vaccination remain unanswered and require further exploration, such as response duration, need for response monitoring and rates of breakthrough infections.
ABSTRACT
Vaccines against COVID-19 have demonstrated a remarkable efficacy in decreasing hospitalisations and deaths; however, clinical trials leading to vaccine approvals did not include immunocompromised individuals such as patients receiving antineoplastic therapies. Emerging data suggest that patients on active anti-cancer therapy may have a reduced immune response to COVID-19 vaccination compared to the general population and may be at greater risk of COVID-19 infection as measures to reduce transmission in the community are relaxed. We report preliminary data from the American University of Beirut Medical Center in Lebanon demonstrating relatively low seroconversion rates. Of 36 patients on active anti-cancer therapy who had received two doses of vaccine, 17% were negative for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) anti-spike IgG. These results highlight the importance of maintaining strict precautionary measures against COVID-19 in patients on immunosuppressive treatment. There is an urgent need for active monitoring of immune response post-vaccination in prospective studies involving populations from diverse resource settings.