No AB to SARS Cov 2; This is a spontaneous report received from a contactable reporter(s) (Physician) from medical information team for a Pfizer sponsored program. The reporter is the patient.  A 51 year-old male patient received bnt162b2 (BNT162B2), intramuscular, administered in deltoid right, administration date 14Aug2021 15:00 (Lot number: FC3181) at the age of 50 years as dose 3 (booster), single, intramuscular, administered in deltoid left, administration date 12Jan2021 11:00 (Lot number: EK4176) as dose 2, single and intramuscular, administered in deltoid left, administration date 24Dec2020 11:00 (Lot number: EH9899) as dose 1, single for covid-19 immunisation. Relevant medical history included: "Hypothyroid" (unspecified if ongoing); "Thyroid CA", start date: 01Feb2014 (unspecified if ongoing); "Thyroidectomy", start date: Jul2016 (unspecified if ongoing), notes: s/p resection 2016; "GERD" (unspecified if ongoing). Concomitant medication(s) included: SYNTHROID taken for hypothyroidism, start date: 2014 (ongoing); PANTOPRAZOLE taken for gastrooesophageal reflux disease, start date: 2018 (ongoing). The following information was reported: SARS-COV-2 TEST FALSE NEGATIVE (non-serious) with onset 09Sep2021, outcome "unknown", described as "No AB to SARS Cov 2". Relevant laboratory tests and procedures are available in the appropriate section.  Additional information: As a health care provider patient was vaccinated early in Dec2020 1st dose and Jan2021 second dose, see attached cards, patient checked his IgG SARS CoV-2 AB. In 07Sep2021 about 3 weeks after his third dose on 14Aug2021-which showed no AB, 6 months post Booster he was contemplating to get a 4th dose, then Feb2022 antibody check was done, and again No AB to SARS Cov-2. Patient had good AB response to other vaccines, he was not immunocompromised. This test is intended for the qualitative detection of antibodies to SARS-CoV-2 in human serum and as in identifying individuals with an adaptive immune response on SARS-CoV-2, indicating recent or prior infection. At this time, in is unknown for how long antibodies persist following infection and to what degree the presence of antibodies confers protective immunity. The Roche Elecsys Anti-SARS-CoV-2 assay should not diagnose acute SARS-CoV-2 infection. Negative results do not preclude SARS-CoV-2 infection. If acute infection is suspected, direct PCR -is recommended. False positive results may occur due to sensitivity from pre-existing antibodies or other possible causes. This assay has overall sensitivity of 100% and specifically- in patients >-14 days post-PCR confirmation. The Elecsys Anti-SARS-CoV-2 assay is - or under the food and Drug Administration's Emergency Use Authorization (EUA) - Testing is limited to Laboratories certified - and perform moderate and high complexity tests. The Abbott SARS-CoV-2 lgG assay is a chemiluminescent microparticle immunoassay Intended for the qualitative detection of IgG antibodies specific to the nucleocapsid protein of SARS CoV-2 serum from patients who are suspected to have had COVID-19 disease. Negative antibody results do not rule out SARS-CoV-2 infection, particularly in those who have been in contact with the virus. Testing with a molecular diagnostic should be considered to evaluate for active infection in these individuals. Results from antibody testing should not be used as the sole basis to diagnosis or exclude SARS-CoV-2 infection or to inform infection status. This test has not been Food and Drug Administration (FDA) cleared or approved but has been authorized by FDA under an emergency use authorization (EUA). This test has been authorized only for the detection of IgG antibodies against SARS-CoV-2, not any other viruses or pathogens. Patient had provide information to you regarding the reported adverse event(s) with the use of product.   No follow-up attempts are possible. No further information is expected.  Follow up (28Feb2022): This is a follow-up spontaneous report received from the same contactable Physician. This Physician (patient) reported in response to HCP letter sent via follow-up letter in which updated information included that: Patient age at vaccination added, patient and Lab data were added, Dosage regimen details added, vaccine facility information added and Concomitant drugs and details updated.  Follow-Up (09Mar2022): Follow-up attempts are completed. No further information is expected.