Pfizer-BioNTech BNT162b2 is one of the three U.S. Food and Drug Administration (FDA)-approved vaccines for the prevention of COVID-19. Its most common side effect, injection site pain, occurs because of locally recruited inflammatory mediators and is mitigated by the lymphatic system. Side effects may discourage individuals from receiving vaccines; therefore, reducing the duration of injection site pain can promote vaccination compliance. Osteopathic manipulative treatments (OMT) can directly affect the physiology underlying muscle soreness; however, there is currently no literature that supports the use of OMT in this scenario. In this case report, an otherwise healthy male presented with acute left deltoid soreness after receiving the Pfizer COVID-19 vaccine. The pain began 5 h prior to the visit. Three hours after being treated with lymphatic OMT, the severity of the pain was significantly reduced and was alleviated 8h after onset in comparison to the median duration of 24–48 h. He received his second dose 3 weeks later. This case report can provide future studies with the groundwork for further investigating the role of OMT in treating postvaccination muscle soreness, which can improve patient satisfaction and potentially promote vaccination compliance.