Vaccination failure; SARS-CoV-2; This is a literature report from the Journal.   A 63-year-old male patient received bnt162b2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, Lot number was EM9810), dose 1 via an unspecified route of administration on Mar2021 dose 1, single and second dose of bnt162b2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, EN6207), via an unspecified route of administration on Apr2021 as dose 2, single for covid-19 immunisation.  Medical history included mild hypertension, benign prostatic hypertrophy, and a body mass index o27, was found to be SARS-CoV-2 positive by reverse transcription polymerase chain reaction (RT-PCR) on June 3, 2021. His 25-yearold son (Patient B), whom he had seen the previous weekend, had developed upper respiratory symptoms and headaches 6 days earlier, and also had a SARS-CoV-2 positive PCR on June 3, 2021. Although Patient A was asymptomatic at the time of testing, he developed nasal congestion, headache, and a dry cough the following day. These symptoms became more pronounced over the next few days and were associated with extreme fatigue and lassitude. His SPO2 was consistently above 98% by self-monitoring, except for a transient drop to 95%. Both patients had previously received two doses of COVID-19 vaccine BNT162b2 (Pfizer-BioNTech, LOT# EM9810, EN6207) 22 days apart in March and April of 2021. After 4 days of symptoms following his diagnosis, Patient A presented to Hospital in New York City. His vital signs were stable, and he was afebrile. A SARS-CoV-2 IgG semi-quantitative anti-spike protein antibody was a strong positive at 178 AU/ml (negativel < 5AU/ml), suggesting a strong immune response to the vaccine. He received mAb infusion (bamlanivimab/etesevimab) and was discharged. He reported feeling a returned sense of well-being with complete resolution of symptoms by the next morning. The close contacts of both patients remained asymptomatic and were negative by repeat SARS CoV-2 PCR testing. The SARS-CoV-2 positive clinical specimens (nasopharyngeal swabs) were further tested by RT-PCR and next-generation sequencing (NGS). COVID-DX software (Biotia) was used to detect genetic variants, define PANGO lineage, and assess clade-level phylogenetic analysis. NGS testing of Patient A identified the B.1.617.2 lineage with 35 mutations detected, including 9 in the spike protein (Figure 1). Patient B had a similar phylogenetic and variant profile to Patient A (B.1.617.2 lineage, with 7/12 shared S-gene mutations). Notably, we detected two spike protein deletions in Patient A that were not present in-Patient B [H69_V70del (ATACATG21764A) and Y145del (TTTA21990T)]. The patients provided informed consent to provide specimen and clinical metadata, and the samples were processed under Protocol Number 00042824 (Advarra Institutional Review Board). DISCUSSION: To our knowledge, this is the first known Delta variant vaccine breakthrough case with hospitalization. Interestingly, the two vaccine breakthroughs in the same family with similar variant profiles of the SARS-CoV-2 virus may be related to host genetics or the specific mutations of a shared virus. At hospitalization, the patient described no fever, no loss of smell or taste, and no shortness of breath, presenting a clinical picture related to Delta variant cases. Despite his SARS CoV-2 IgG being strongly positive, he was treated with mAb (bamlanivimab/ etesevimab) and his symptoms resolved quickly. The mAb therapy potentially influenced the patients clinical course as within 12 hours of receiving this therapy the patient got better and within 24 hours, he was completely free of all symptoms he had been suffering within the previous three days. Genomic surveillance of novel variants in SARS-CoV-2 positive cases, especially vaccine breakthrough cases, as well as collection of related clinical metadata and therapeutic outcomes, will be necessary to fight the virus as it continues to evolve.; Sender's Comments: Based on the available information in the case, the causal association between the events vaccination failure, COVID-19 and the suspect drug BNT162B2 cannot be excluded.,Linked Report(s) : 202101392635 Same article/ drug/event and different patient