Résumé
Background: Patients with cancer, whose immune responses to vaccines are commonly weaker than those of the general population, are recommended a booster dose after two initial doses of Covid-19 vaccine. Our objective was to compare the humoral immunogenicity of Covid-19 vaccines in patients with cancer compared to healthy adults (control group) after primary vaccine series and after a booster dose.Methods: We included participants aged ≤75 and vaccinated with two doses in the primary vaccine series and a booster, from the French national prospective Covid-19 vaccine cohort study (ANRS0001S COV-POPART) and excluded those with SARS-CoV-2 infection. Percentage of responders, geometric mean titers (GMT) of anti-SARS-CoV-2 IgG antibodies (ELISA) and specific neutralizing antibodies against original strain, Delta and Omicron variants of concern, were estimated one month after the primary vaccine series, then one month and six months after a booster dose.Results: We included 183 patients with cancer and 1173 controls. The most frequent cancers were breast (37.2 %) and lung cancer (17.5 %). Patients with cancer were older and had lower anti-Spike IgG levels after the primary vaccine series (GMT = 132.4 vs 332.7 BAU/mL, P < 0.0001), but they developed similar response at one month (GMT = 2146.1 vs 1841.3 BAU/mL], P = 0.16) and six months after booster (602.0 vs 574.4 BAU/mL, P = 0.80). Neutralizing antibodies levels confirmed these results.Conclusion: Patients with cancer have comparable response rates to controls one month and six months after a booster dose. Our results support the benefit of a booster dose in patients with cancer.