severe breakthrough COVID-19 with a heavily mutated variant; Lack of drug effect; This literature-non-study case was reported in a literature article and describes the occurrence of COVID-19 (severe breakthrough COVID-19 with a heavily mutated variant) in a 61-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Multiple myeloma in remission (kappa light chain in complete remission) since September 2020. Concomitant products included IXAZOMIB, LENALIDOMIDE (LENALIDOMIDE ACCORD) and METHYLPREDNISOLONE for Multiple myeloma.   On 30-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 24-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 08-May-2021, the patient experienced COVID-19 (severe breakthrough COVID-19 with a heavily mutated variant) (seriousness criterion medically significant) and DRUG INEFFECTIVE (Lack of drug effect). On 08-May-2021, DRUG INEFFECTIVE (Lack of drug effect) had resolved. In 2021, COVID-19 (severe breakthrough COVID-19 with a heavily mutated variant) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 26-Jan-2021, Blood immunoglobulin A (101-645): 131 mg/dl (normal) 131 mg/dl. On 26-Jan-2021, Blood immunoglobulin G (540-1822): 776 mg/dl (normal) 776 mg/dl. On 26-Jan-2021, Blood immunoglobulin M (22-240): 47 mg/dl (normal) 47 mg/dl. On 26-Jan-2021, Light chain analysis (3.3 mg/l-19.4 mg/l): 15.7  mg/l (normal) 15.7 mg/L and 22.7 mg/l (normal) 22.7 mg/L. On 26-Jan-2021, Lymphocyte count (1 × 10^3/µl-5 × 10^3/µl): 1.52 (normal) 1.52 × 10^3/µ. On 17-Feb-2021, SARS-CoV-2 antibody test: 34.6 iu/ml 18 days after dose 1. On 17-Mar-2021, SARS-CoV-2 antibody test: 608 iu/ml 21 days after dose 2. In April 2021, SARS-CoV-2 antibody test: 126 iu/ml 8 weeks after second dose (consistent with a  half-life of 16.3 days, calculated by exponential decay). On 08-May-2021, SARS-CoV-2 test: positive (Positive) Sequencing revealed an extensively mutated B.1.628 SARS-CoV-2 variant with 10 mutations in spike protein, including E484Q and N440K and positive (Positive) with cycle thresholds of 20.8 (Ngene) and 21.8 (E-gene). On 08-May-2021, Viral load: approximate 400,000 Approximate 400,000. On 21-May-2021, SARS-CoV-2 antibody test: 37,400 iu/ml 13 days after the positive PCR for COVID-19 and 23 days after the likely exposure on 4/28, increased over 250-fold to 37,400 IU/mL.. On 28-May-2021, SARS-CoV-2 antibody test: 34,700 iu/ml 34,700 IU/mL. On 20-Jul-2021, SARS-CoV-2 antibody test: 4070 iu/ml 4070 IU/mL. On an unknown date, Body temperature: 101 °f 101 °F. On an unknown date, Oxygen saturation: 92 % 92 %. On an unknown date, SARS-CoV-2 antibody test: 5.74 iu/ml Baseline anti-spike IgG of 5.74 IU/mL (below the assay background of 50 IU/mL).     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered COVID-19 (severe breakthrough COVID-19 with a heavily mutated variant) and DRUG INEFFECTIVE (Lack of drug effect) to be related.    Patient had no evidence of pre-existing immunity to COVID-19. Patient was thought to confer significant protection after vaccination, as the second value was 37th percentile when compared to similar specimens from vaccinated healthy controls in our recently published study.  Patient left the Country and flew to Country and developed pharyngitis, myalgias, rhinitis, and severe coughing resulting in a subconjunctival hemorrhage on returning home. He subsequently developed diaphoresis and fever. Patient met with the criteria for severe COVID-19 with an oxygen saturation of 92% but declined hospitalization. Symptoms persisted for another 10 days before beginning to improve, and he recovered fully during the next month.  Company comment: This literature non-study case concerns a 61-year-old male patient with a relevant medical history of Multiple myeloma in remission undergoing treatment with Lenalidomide, Ixazomib and Methylprednisolone, who experienced the unexpected - according to CCDS - serious (medically significant) event of COVID-19 (AESI) after mRNA- 1273 Moderna vaccine. Additionally, Drug ineffective was considered. The event occurred approximately 10 weeks after the second dose of mRNA- 1273 vaccine. Clinical manifestations included pharyngitis, myalgias, rhinitis, cough, pyrexia and decreased oxygen saturation (S92%). The patient had criteria for hospitalization, but declined it.  SARS-CoV-2 test was positive, sequencing was performed and showed a B.1.628 SARS-CoV-2 variant. His symptoms had a duration of 10 days, and patient fully recovered after 1 month. Previous history of Myeloma multiple and concomitant immunosuppressive regimen remain as confounder. The benefit-risk relationship of mRNA- 1273 vaccine is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 21-Dec-2021: Follow-up received by safety on 21-Dec-2021 included an Email with Administration received from team; Sender's Comments: This literature non-study case concerns a 61-year-old male patient with a relevant medical history of Multiple myeloma in remission undergoing treatment with Lenalidomide, Ixazomib and Methylprednisolone, who experienced the unexpected - according to CCDS - serious (medically significant) event of COVID-19 (AESI) after mRNA- 1273 Moderna vaccine. Additionally, Drug ineffective was considered. The event occurred approximately 10 weeks after the second dose of mRNA- 1273 vaccine. Clinical manifestations included pharyngitis, myalgias, rhinitis, cough, pyrexia and decreased oxygen saturation (S92%). The patient had criteria for hospitalization, but declined it.  SARS-CoV-2 test was positive, sequencing was performed and showed a B.1.628 SARS-CoV-2 variant. His symptoms had a duration of 10 days, and patient fully recovered after 1 month. Previous history of Myeloma multiple and concomitant immunosuppressive regimen remain as confounder. The benefit-risk relationship of mRNA- 1273 vaccine is not affected by this report.