SUSPECTED IMMUNOLOGICAL VACCINE FAILURE; REVACCINATION WITH DIFFERENT COVID-19 VACCINE; This spontaneous report was received from literature. This report concerned 3 multiple patients of an unspecified age, sex, race and ethnicity. The objective of the authors was to study the In-Depth Cellular and Humoral Dynamics of the Response to COVID-19 Vaccine Booster in Patients with Chronic B-Cell Neoplasms.  The patient's height, and weight were not reported. The patient's concurrent conditions included: non-hodgkin lymphoma, b-cell neoplasms, and chronic lymphocytic leukemia. The patients received covid-19 vaccine ad26.cov2.s (dose number in series 1) (suspension for injection, route of admin, and batch number were not reported, expiry: unknown) 1 total, dose and start therapy date were not reported for covid-19 prophylaxis. The batch number was not reported and has been requested. No concomitant medications were reported.  The patients received non-company suspect vaccine Moderna covid-19 vaccine (elasomeran) (dose number in series 2) (form of admin, route of admin not reported, batch number: Unknown, expiry: Unknown) dose, start therapy date were not reported for covid-19 prophylaxis which was associated with revaccination with different covid-19 vaccine (dose number in series 2). In this study, the cut-off of the IgG antibodies to SARS-CoV-2 spike RBD (receptor-binding domain) assay was considered as 1 microgram/ milliliter, Hence therapy non-responders were defined as patients with Immunoglobulin G (IgG) to S-RBD below 1 microgram/ milliliter. The patients were classified as antibody responders if their IgG level at 3 weeks post-booster was greater than 1 microgram/ milliliter.  Out of total 56 patients, 3 patients (10 percent) who had received first dose of covid-19 vaccine ad26.cov2.s followed by second dose of Moderna covid-19 vaccine (elasomeran), on an unspecified date, the patients had less than 1 microgram/ milliliter of Immunoglobulin G (IgG) antibodies who were reported as therapy non-responders which was coded as suspected immunological vaccine failure (dose number in series 1). The action taken with covid-19 vaccine ad26.cov2.s, and elasomeran was not applicable. The outcome of the suspected immunological vaccine failure and revaccination with different covid-19 vaccine was not reported. The authors concluded that, findings provide new insight into the nature of humoral and T-cell responses to SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) vaccine booster and in vivo cellular dynamics in patients who have chronic B-cell neoplasms. The results support the usefulness of vaccination in patients with CLL (chronic lymphocytic leukemia) to boost anti-viral T cells, even in the absence of antibody responses, and shed new light on the determinants and variability of vaccine response. The differences in vaccine response between disease types warrant further investigation of the biology of adaptive responses in patients with distinct B-cell malignancies. This report was serious (Other Medically Important Condition). This case, from Same Literature article is linked to 20230808152. This report was associated with a product quality complaint and reference number requested.; Sender's Comments: V0: 20230835813-Suspected immunological vaccine failure. The event has an unknown/unclear temporal relationship, is unlabeled, and has unknown scientific plausibility. There are other factors more likely to be associated with the event. Specifically: SPECIAL SITUATIONS. Therefore, this event is considered inconsistent with vaccine administration.