Impaired acute‐phase humoral immunity is the major factor predicting unfavorable outcomes in multiple myeloma patients with SARS‐CoV‐2 Omicron variants outbreak infection.

At the end of 2022, a huge tide of SARS‐CoV‐2 infection mainly Omicron BA.4/5 developed in China. Multiple myeloma (MM) patients suffered cancer deterioration and mortality from COVID‐19, yet profound analyses of Omicron variants‐induced immunity function are scarce. We presented a longitudinal study in 218 MM patients and 73 healthy controls (HCs), reporting the prognostic factors and dynamic humoral and cellular immune responses. Neutralizing antibody and interferon γ ELISpot assay of SARS‐CoV‐2 was tested at three time points: 2–4, 8–10, and 14–16 weeks after infections. Our data showed older age, active MM, relapsed/refractory MM (R/RMM), immunotherapy, comorbidity, and non‐vaccination were risk factors associated with hospitalization. Severe humoral immunity impairment within 2–4 weeks was especially seen in patients with unvaccinated, older age, immunotherapy, R/RMM and comorbidities, while T‐cell response was relatively intact. Although antibodies of Omicron variants reached positive levels in MM patients at 8–10 weeks, half lost effective antibody protection at 14–16 weeks. However, most seronegative patients (76.2% at 2–4 weeks, 83.3% at 8–10 weeks) could develop effective T‐cell response. Notably, the inactivated wild‐type vaccinated patients exhibited weaker humoral and cellular immunity only at 2–4 weeks, escalating to similar levels as those in HCs later. Our findings indicate impairment of humoral immunity at acute‐phase after infection is the major factor correlated with hospitalization. One‐month suspension of immune therapy is suggested to prevent serious infection. These results confirm the value of inactivated vaccine, but indicate the need for additional booster at 14–16 weeks after infection for high‐risk MM population. [ABSTRACT FROM AUTHOR]