shingles; so he thought it was just a pulled muscle; Back pain; soreness in the arm; This is a spontaneous report from a contactable other health professional via the Pfizer-sponsored program.   A 77-year-old male patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE), via an unspecified route of administration (at the age of 77-years-old), administered in Arm Left on 26Jan2021 13:30 (Lot Number: EL9263) as 1st dose, single for COVID-19 immunization. Medical history included penicillin allergy. It's been 25-30 years ago and he can't take it. He gets swollen and hives and sick. There were no concomitant medications. The patient previously received a shingles shot about 5-6 years ago and flu shot Nov2020. The patient experienced soreness in the arm on 26Jan2021, back pain on 30Jan2021, so he thought it was just a pulled muscle on Feb2021, shingles on 15Feb2021. The patient received the first COVID shot on 26Jan2021 and didn't really have a reaction, but soreness in the arm a couple of days. He then started having back pain and he is a very active person so he didn't think anything of it. Spouse told him that he needs to see the doctor because she thought he had shingles. They do not know if it's associated to the COVID shot or not. They need to also cancel his appointment for tomorrow because the doctor does not want him to get his second COVID shot since he is on medication for the shingles. Mentions again, his arm was a little sore, but then 4 days after that he had back pain. He is an exceptionally active person, and excavation construction worker and still works and so he thought it was just a pulled muscle. Then a few days later, pain was awful and area was sensitive to touch and it looked a little swollen and he had nothing else. A couple days later he kept saying it bothered him and it was all the way around to his side. It was fine at first it started with a little rash and so he went to the doctor today and diagnosed with shingles. Therapeutic measures were taken as a result of shingles which included valacyclovir (Was given Valacyclovir 1 gram tablet to take three times daily to help the shingles). Adverse events required a visit to Physician Office. The outcome of the event "soreness in the arm" was recovered on 28Jan2021, for Back pain and shingles was not recovered, for "so he thought it was just a pulled muscle" was unknown. No other vaccines given the same day or 4 weeks prior. No problem with vaccines in past.   Follow-up attempts are completed. No further information is expected.; Sender's Comments: Based on the information currently available, a possible contributory role of the suspect vaccine BNT162B2 or comirnarty in triggering the onset of Herpes zoster,sorenessin the arm,backpain,pulled muscle cannot be excluded.But also consider.medical history of allergic drug history and other relevant medical history.The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to Regulatory Authorities, Ethics Committees and Investigators, as appropriate.