COVID-19 Vaccination in Oncology Patients Receiving Chemotherapy.

Madam — We read with interest Sudan et al.’s Letter ‘Optimal timing for COVID-19 vaccination in oncology patients receiving chemotherapy?’ [1]. We agree that the immunogenic efficacy of the vaccine is an important issue when vaccinating cancer patients receiving chemotherapy. However, another important issue that should not be forgotten is safety. Sudan et al. [1] have already mentioned the change in immune status, optimal timing for vaccination and risk of serious COVID-19.

Moreover, the administration of a COVID-19 vaccine can induce increased blood viscosity, as there is a rapid production of antibody protein in the plasma after vaccination [2]. In a cancer patient receiving chemotherapy, increased blood viscosity might occur [3]. During chemotherapy there is rapid cell lysis, which may cause a change in the protein component in the plasma [3]. Therefore, there is a possibility that hyperviscosity could occur. It is necessary to monitor the blood viscosity of cancer patients to prevent hyperviscosity. Therefore, it may not be appropriate to give a COVID-19 vaccine during chemotherapy.

Conflict of interest

The authors declare no conflict of interest.