Cancer patients have a higher risk of developing severe symptoms from a COVID-19 infection. Many cancer patients undergoing active cancer therapy are immunocompromised, making them even more susceptible to contracting COVID-19.
Protecting vulnerable populations, including cancer patients, from COVID-19 is a high priority for public health. Therefore, the efficacy of COVID-19 vaccines is an essential factor for patients and their doctors to consider.
Encouraging data published recently by a team of researchers in JAMA Oncology suggests that most cancer patients who received two doses of the BioNTech-Pfizer mRNA vaccine still retained immunity four months after vaccination.
The researchers measured titers of anti-spike (anti-S) immunoglobulin G (IgG) antibodies against SARS-CoV2 in blood samples from 95 cancer patients with various solid tumors who were undergoing systemic therapy. The most prevalent cancer types in the study were gastrointestinal, lung, and breast. Patients received different treatments, including chemotherapy, immunotherapy, and biological therapy. Some patients received more than one therapy.
Seropositivity, the presence of a specific marker in the blood, was defined as 50 or greater AU/ml. Therefore, blood samples deemed positive contained COVID specific antibodies which may protect from COVID-19 infection. Previous data from the same group of patients found that 92% exhibited seropositivity at an average of 28 days following the second dose of vaccination.
Approximately four months (an average of 123 days) after the second dose of vaccine, 87% of patients tested positive for anti-S IgG antibodies. The anti-S IgG titers varied by tumor type and therapy. The research team detected the lowest titers in patients receiving immunotherapy plus chemotherapy/biological therapy.
The study also included 66 healthy controls chosen from caregivers accompanying patients to treatment. Notably, 100% of the controls tested positive for anti-S IgG antibodies in both the current and previous studies.
While vaccinated patients undergoing cancer treatment generate less anti-S IgG than healthy individuals, the authors conclude that the seropositivity rate remains high for most of these cancer patients up to four months after vaccination.