Evaluation of immune response to anti‐COVID‐19 booster in cancer patients and chronic medical cannabis users and its association with circulating Eosinophils levels

Dear Editor On July 29, 2021, the Israeli Ministry of Health approved the third anti-Coronavirus disease 2019(COVID-19) vaccination (3rd-BNT162b2-booster-dose), leading to a sharp daily drop in diagnosed positive COVID-19 cases and mortality rates in Israel [1]. The booster dose increased severe acute respiratory syndrome coronavirus-2(SARS-CoV-2) neutralization efficiency approximately a hundred-fold compared to individuals receiving only the second dose, providing significant protection against infection [2]. Due to their immunocompromised condition, cancer patients may be more susceptible and generally more vulnerable to infections [3]. Indeed, due to the chronic weakening of their immune system, cancer patients are at higher risk of developing severe clinical outcomes from SARS-CoV-2 infection and are associated with an increased risk of morbidity and mortality [3]. Cancer patients treated with anticancer drugs or undergoing major surgery have double the risk of developing a severe illness, hospitalization, and death due to COVID19 [3, 4]. Early studies on cancer patients in Israel who received the second BNT162b-booster-dose indicated a noticeable lag in antibody production compared to controls, despite the comparable seroconversion rate tested four weeks after administration [5]. No adverse effects or interaction between immunoglobulin G (IgG) levels and active anticancer therapies, such as chemotherapy or radiation, were reported [4]. Recently, a study evaluating immune response 4-weeks after administration by cancer patients receiving the 3rd-BNT162b2-boosterdose indicated an efficient anti-COVID-19 immunity when neither gender nor chemotherapy status was associated