Slight pain in left arm; a dose of the vaccine was diluted with 0.18mL of diluent instead of the recommended 1.8m and this dose was administered to a patient; a dose of the vaccine was diluted with 0.18mL of diluent instead of the recommended 1.8m and this dose was administered to a patient; This is a spontaneous report from a Pfizer-sponsored program. A contactable Other-HCP reported that a patient of 39 age and gender received bnt162b2 (BNT162B2 Formulation: Solution for injection), dose 1 0.3 ml single via an Intramuscular route and Left arm, of administration on an date 03Sep2021 10:00 (Batch/Lot number: EWO187, Expiry date: unknown) as DOSE 1 0.3 ML SINGLE for covid-19 immunization. The patient medical history was not reported. The patient's concomitant medications were not reported. The patient experienced a dose of the vaccine was diluted with 0.18ml of diluent instead of the recommended 1.8m and this dose was administered to a patient and a dose of the vaccine was diluted with 0.18ml of diluent instead of the recommended 1.8m and this dose was administered to a patient on an 03Sep2021 10:00 date and outcome recovered 03 Sep2021 10:00. The Pfizer covid 19 vaccine/Comirnaty confirmed. Onset date 03Sep2021 10:00 reports that a dose of the vaccine was diluted with 0.18mL of diluent instead of the recommended 1.8m and this dose was administered to a patient outcome recovered on 03Sep2021 10:00. The Patient had slight pain in left arm, onset dates and Event outcome unknown.  The reporter was asked for guidance on scheduling the second dose of the vaccine. The patient had underwent of Lab data blood pressure 160/90 mmHg unknown date.  Clinical information: The patient was provided information to you regarding the reported adverse event with the use of the product. The patient had considered the Pfizer product had a causal effect to the adverse event. The patient and reporter had contacted again by Pfizer on the reported adverse event. The patient had dose: 1 on date: 03Sep2021 10:00 by the site and route of injection: left arm, intramuscular along with batch lot number: EWO187. The patient had dose: 2 on Date: 24Sep2021 10:00 by site and route of injection: left arm, intramuscular with batch lot number: EWO187.The vaccination facility information was privacy. Their was no prior vaccinations and concomitant drugs as well as patient medical history were none. The patient had adverse events with term of extra dose on date: 03Sep2021 10:00. The reporter was reported non seriousness criteria. The patient had AE required visited physician office and AE outcome was recovered unspecified date treatment was not used. The patient had dose 2 AE term adverse event on administered date: 24Sep2021 10:00. The patient had non seriousness criteria. The AE required visited physician office and AE outcome was Recovered unspecified date treatment not used.  The reporter was reported for dose 1: Using lot EWO0187, vial was diluted with 0.18 ml of diluent. Patient was administrated 0.3 ml dose on stage: preparation. The patient had event slight pain in left arm. The patient had dose 2: Patient was given correctly diluted dose, patient had reported headache. The lab data had Blood pressure was measured to be 160/90 mmHg.  Follow-up (05Oct2021). The following information was received from a contactable pharmacist: New information included - Clinical information added.  No follow-up attempts are possible. No further information expected.