Boosting capacity of a fourth dose BNT162b2 in cancer patients

Due to their immunocompromised status, cancer patients have reduced immune responses against SARS-CoV-2 after dual-dose COVID-19 vaccination [1]. A third primary dose has been recommended for this population as various studies showed its ability to boost the humoural immune response against SARS-CoV-2 [2,3]. However, it is presumed that after this third primary vaccination dose, the vaccination-induced protection against SARS-CoV-2 will wane rapidly, as seen after dual-dose vaccination [2,4,5]. This in combination with the emergence of highly transmissible SARS-CoV-2 variants, such as omicron BA.1, suggested that a fourth vaccination doses against SARS-CoV-2 may be beneficial for cancer and other immunocompromised patients, aiming to improve the protection against COVID-19.