In a study conducted by Dr Romain Palich of the Medical Oncology department, Pitié-Salpêtrière hospital in Paris, France and colleagues almost half patients with cancer showed no anti-spike antibody response after a first injection of BNT162b2 (Pfizer-BioNTech) vaccine, and this low seroconversion rate was much worse in elderly patients and in those under chemotherapy. Moreover, even in patients with seroconversion, the level of antibody response was lower than expected. Findings from the study on antibody response 4 weeks after the first injection of the BNT162b2 vaccine in patients with cancer and healthcare workers as the control population were published on 28 April 2021 in the Annals of Oncology.

Patients with cancer on active treatment or who were treated in last two years and healthcare workers who received vaccine between 17 February 2021 and 18 March 2021 at the Pitié-Salpêtrière hospital were included in this analysis. Titration of antibodies was done just before the second injection of BNT162b2 vaccine.

The antibodies were measured in 110 patients with cancer and 25 healthcare workers. In patients with cancer who did not have COVID-19 before vaccination, the seroconversion rate was only 55% versus 100% in healthcare workers. Titers of antibodies were significantly higher in healthcare workers when compared with seropositive patients with cancer, in particular 680 versus 315 UA/mL (p = 0.04).

Gender, cancer locations and metastatic status were similar in patients with cancer with seroconversion and non-seroconversion.

After adjustment for potential confounders, age over 65 (odds-ratio [OR] 3.58, 95% confidence interval [CI] 1.40-9.15, p = 0.008) and treatment with chemotherapy (OR 4.34, 95% CI 1.67-11.30, p = 0.003) were two factors that have strongly associated with no seroconversion.

No symptomatic COVID-19 occurred between the two vaccine injections neither in patients with cancer nor healthcare workers.

The study team argued for not extending the 21-day period between the two vaccine injections in patients with cancer and for performing serological monitoring to assess antibody response in this population. They also recommended COVID-19 vaccination among family and friendship circles.

This study was approved by the Commission Nationale de l’Informatique et des Libertés.


Palich R, Veyri M, Marot S, et al. Weak immunogenicity after a single dose of SARS-CoV-2 mRNA vaccine in treated cancer patients. Annals of Oncology; Published online 28 April 2021; DOI: