decline in muscle function; sick; aches and pains all over his body; did not feel well; muscle mass; scared; he really thinks the biologics in the Humira he takes and the biologics in the vaccine are counter acting each other and putting him into a major flare; he really thinks the biologics in the Humira he takes and the biologics in the vaccine are counter acting each other and putting him into a major flare; generalized aches and pains; This is a spontaneous report from a contactable other HCP (patient's mother). This other HCP reported for patient (reporter's son). A 42-year-old male received (age at vaccination: 42 year) first dose of BNT162B2 (PFIZER-BIONTEC COVID-19 mRNA VACCINE, Solution for injection, lot number: EW0169 and expiry date was reported), via an unspecified route of administration, in Arm Right, on 22Apr2021, as a single dose for COVID-19 immunization. The patient's medical history included spinal muscular atrophy, osteoporosis, and ankylosing spondylitis. Concomitant medications included adalimumab (HUMIRA) which was started about a year and a half ago for ankylosing spondylitis, denosumab (PROLIA) which started about a year ago for osteoporotic bones and Evrysdi: (Start: Dec 2020 Stop: Ongoing). This female consumer reported her son/patient received his first injection of the Pfizer covid-19 vaccine on 22Apr2021. The patient has been taking Evrysdi over the past year and experienced some gains in muscle function. After receiving the Pfizer covid-19 vaccine, the patient began experiencing a decline in muscle function described further as losing all the muscle function he had gained while taking Evrysdi. The reporter/mother said her son has been sick ever since receiving the Pfizer covid-19 vaccine and was experiencing flare-up and been prescribed prednisone as treatment. The reporter stated that since their son got the vaccine, he had gone downhill and clarified he had generalized aches and pains all over his body since the vaccine, mostly in the spinal and sacral area, but they were also in his arms, elbows, everything ached, he really did not feel well and could not do anything he used to do after the vaccine. He was starting to gain muscle mass and everything and since the vaccine all that was gone. The reporter stated they took him to both doctors, and they have been zooming with him and want him to get the second dose. He really thinks the biologics in the Humira he took and the biologics in the vaccine were counter acting each other and putting him into a major flare. The patient was treating symptoms with a dose pack of prednisone, getting a little better but did not have strength back at all. The reporter also stated that prior to this vaccine, the doctors were saying was an anomaly, the newer medication he was on was supposed to stop the progression of muscular dystrophy and he was doing so well on the medication until he got the vaccine. The patient was scared he was going to get worse; they were looking for information about getting the second dose, stated their doctors did not have a lot of information. The reporter asked could the Pfizer COVID-19 vaccine reverse the progress our son made in his muscles while taking Evrysdi for spinal muscular atrophy and should her son get the second dose after what has happened after the first dose of the Pfizer covid-19 vaccine. Also asked how long you could wait to get the second dose of the Pfizer covid-19 vaccine and was there an interaction with Humira. The reporter got response that spoke per FAQ and referred to HCP. Outcome of the event generalized aches and pains was not recovered and for all other events, it was unknown.  Additional information has been requested and will be provided as it becomes available.