arm pain at the injection site; feeling markedly tired; had just a slight muscle pain; he felt particularly off; This is a spontaneous report from a contactable consumer (patient). A male patient of an unspecified age received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE, Formulation: Solution for injection, Batch/Lot number was not reported) via an unspecified route of administration on 27Jul2021 as dose 1, single for COVID-19 immunization. The patient's medical history and concomitant medications were not reported. The patient experienced arm pain at the injection site, feeling markedly tired, had just a slight muscle pain, he felt particularly off on 28Jul2021. Reported as, reporter stated he felt fine after the injection; he even felt "relaxed." He stated that he always gets up at 4am to meditate and exercise until 8am, but this morning when he woke up at 4am, he felt particularly "off". Reported feeling markedly tired and stated his arm where he received the injection "feels like withheld whacked me in the side of the arm". Reporter asking how long the tiredness may last. Reported when he woke up he felt tired and had just a slight muscle pain but he still went and worked out it was just more laborious. Caller said that yesterday he got the 1st dose and he felt fine and his call wasn't an emergency or anything but he has been reading the literature and he guessed that he wanted to ask how long do these side effects will last. He woke up this morning and usually he woke up at 4 every day and he meditates and trains for triathlons, so he was pretty fit, but when he woke up he felt tired and had just a slight muscle pain but he still went and worked out it was just more laborious. He guess if he was feeling any effect the most it was being tired, and he didn't get tired. His question was how long do the side effects last. Patient was informed that tiredness and arm pain were some of the more commonly reported side effects of the Pfizer BioNTech Covid-19 Vaccine. The safety evaluation of participants was still ongoing. Participants were asked about local and systemic events, and use of fever reducing medication after each vaccination. Participants continued to be monitored for non-requested adverse events, including serious adverse events up to 6 months after the last vaccine dose. Among the Pfizer-BioNTech COVID-19 Vaccine recipients, mild-to-moderate pain at the injection site within 7 days after an injection was the most commonly reported local reaction, with less than 1% of participants across all age groups reporting severe pain. In general, local side effects; the ones you get on the arm where you got the shot (such as injection site redness and injection site swelling) were mostly mild-to-moderate in severity and resolved within 1 to 2 days. Side effects that you may experience throughout the rest of your body; (systemic side effects) including fever and chills were observed with the first 1 to 2 days after vaccination and resolved shortly thereafter. COVID-19 vaccination will help protect you from getting COVID-19. You may have some side effects, which are normal signs that your body is building protection. These side effects may affect your ability to do daily activities, but they should go away in a few days. Side effects after your second shot may be more intense than the ones you experienced after your first shot. These side effects are normal signs that your body is building protection and should go away within a few days. These side effects usually start within a day or two of getting the vaccine. Side effects might affect your ability to do daily activities, but they should go away in a few days. Call the vaccination provider or your healthcare provider if you have any side effects that bother you or do not go away." Outcome of the event "he felt particularly off " was unknown and not recovered for rest of the events.  The lot number for the vaccine [BNT162B2] was not provided and will be requested during follow up.  Follow up attempts are completed. No further information is expected.