Age: 81.0
Sex: F
Vaccine: COVID19
Symptoms: Pain in extremity, Underdose
Clinical narrative: sore arm; he gave me a half a dose of the regular dose for an adult; This spontaneous case was reported by a patient and describes the occurrence of PAIN IN EXTREMITY (sore arm) and UNDERDOSE (he gave me a half a dose of the regular dose for an adult) in an 81-year-old female patient who received SPIKEVAX NOS (SPIKEVAX NOS) for COVID-19 prophylaxis.     The patient's past medical history included Pacemaker insertion (cardiac), Physical therapy (had physical therapy for 4.5 months following the Pfizer shot) and Hospitalization (I was in the hospital for a week). Previously administered products included for Drug use for unknown indication: z-pack erythromycin tablets (z-pack erythromycin tablets), Maxide, z-pack erythromycin tablets (z-pack erythromycin tablets), Maxide, Penicillin and Maxide; for Product used for unknown indication: Pfizer vaccine (Dose 2), Pfizer vaccine (Dose 1), Pfizer vaccine (Dose 2), Flu Shot, Pfizer vaccine (Dose 1), Pfizer vaccine (Dose 2), Pfizer vaccine (Dose 1), Pfizer vaccine (Dose 1) and Pfizer vaccine (Dose 2). Past adverse reactions to the above products included Adverse drug reaction NOS with Pfizer vaccine, Pfizer vaccine and z-pack erythromycin tablets; Allergic reaction NOS with Penicillin; Concussion with Maxide; Fall with Maxide; Frozen shoulder with Pfizer vaccine and Pfizer vaccine; Neck stiffness with Pfizer vaccine and Pfizer vaccine; Pain in arm with Pfizer vaccine, Pfizer vaccine and z-pack erythromycin tablets; Passed out with Maxide; and Vaccination adverse reaction with Flu Shot. Family history included Penicillin allergy (diagnosis from childhood) since an unknown date. Concurrent medical conditions included Allergy (allergy issues/ I'm allergic to whatever it is) and Allergy to antibiotic.   On an unknown date, the patient received dose of SPIKEVAX NOS (SPIKEVAX NOS) (Intramuscular use) 1 dosage form. On an unknown date, the patient experienced PAIN IN EXTREMITY (sore arm) and UNDERDOSE (he gave me a half a dose of the regular dose for an adult). At the time of the report, PAIN IN EXTREMITY (sore arm) had resolved and UNDERDOSE (he gave me a half a dose of the regular dose for an adult) outcome was unknown.      No concomitant medications were reported.  It was reported that patient had a weight of around 103104 lbs, and she had been 5 feet tall. She also reported that, due to having many allergy issues, it had been very difficult for her to distinguish them from a normal reaction. She had received a couple of Moderna shots, with the last one administered in late September or early October of 2024. She reported that she had known it had been "banned" because she had visited her sister in another state. She had received the shot and, upon seeing the actual vaccine and the needle going into her arm, had experienced a burning sensation and pain. This discomfort had lasted intermittently for around 33 weeks before subsiding. Then, moving forward to late March or early April, she had not had the data on her regarding a visit to the doctor but had been prescribed medication, of which she had taken one pill and had subsequently experienced heartburn and acid reflux. She had also taken Doxycycline, after which she had contacted the doctor's office and discarded the pills. She had reported that she had not been sick until the time of reporting; however, she had mentioned that, in the past, she had taken Z-Pack Erythromycin tablets, for which she had obtained a prescription that had been filled on April 4th or 5th. She had been uncertain but had reiterated that it was likely the 5th when she had taken only one of the tablets, which had caused her to have a very severe reaction. It had been the same reaction she had previously experienced when she had received her first COVID-19 shots at the beginning of the pandemic, during which she had "taken" two namely, the two original Pfizer vaccines and the second Pfizer vaccine.  She had experienced tensed or froze the muscles in her neck and shoulders, which was exactly what had occurred after taking erythromycin. In addition, she had felt pain at the site where she had received the Moderna shot, and as the previous night, it had been burning and painful, persisting in that manner. She had then questioned whether anyone else had experienced a similar reaction and had wondered whether the person who had administered the shot had injected it into the muscle or the nerve. She had been uncertain about what had caused that reaction and why she had now developed the same reaction to an antibiotic. She had reported that she had been trying to work with a pharmacist who might be able to help her understand her condition. She had believed that there was something in the fillers common to both the vaccine and the antibiotic, to which she was allergic. However, she had reported that she had been unable to determine exactly what the cause had been and had struggled to figure it out. She had asked whether anyone else had experienced similar pain and burning sensations, and if that had been the case, she had wondered why she had not experienced such reactions before. She had mentioned that she had visited the Moderna website to check for information about potential side effects while gathering details.  She had stated that her weight had fluctuated between 100 and 103 pounds and that she had been 5 feet tall. She had recounted that after receiving the Pfizer shot, her allergy doctor, who had been licensed to administer the Moderna vaccine, had given her a half dose initially because she had required a booster shot. He had provided her with half the standard adult dose. Later she had questioned whether the dosage had been too high for her body weight. She had also mentioned that she had undergone a titer test, which had shown a result of around 100%. Her healthcare provider had then recommended that she receive the full dose and had stated that, for her last couple of Moderna booster shots, she had received the full adult dosage. She wanted to know whether the provider had administered the shot into a muscle or a nerve, as she had wondered whether that had caused the reaction. She had mentioned that she had not experienced such a reaction previously and had suspected that the shot had likely been injected into a muscle. She had believed this to be the case because, based on her reaction to the antibiotic and the Pfizer vaccine, the effects had appeared to have involved the muscles. She had described the reaction as causing her muscles to feel frozen, extremely tight, or strained. She had explained that, prior to contacting MIS, she had consulted her allergy doctor, who had advised her to be cautious and had provided specific instructions, particularly regarding antibiotics. He had warned her against taking antibiotics unless she had confirmed a bacterial infection. She had also mentioned that she had been allergic to penicillin since childhood, which had concerned her doctor. Additionally, she had visited her orthopedic surgeon, who had prescribed physical therapy for her muscle issues in the neck and shoulders. She had noted that, while the reaction had not been as severe as the one she had experienced with the Pfizer vaccine, it had still been a concern. Although the surgeon had not been particularly worried about the Moderna shot, she had felt that it had contributed to the overall reaction affecting her shoulder. She had mentioned that she had undergone physical therapy for 4.5 months following the Pfizer shot, as prescribed. She had claimed that she had continued therapy for as long as necessary and had felt fine until she had taken the antibiotic. She had initially received two Pfizer shots at the start of the pandemic. Every booster shot she had received since then had been Moderna. She had stated that the last shot she had received, in September or October of 2024, had been the first to cause significant pain and burning sensations. She had recalled that, prior to that, she had typically experienced a sore arm for a few days or a week before the discomfort had resolved. She had compared her reaction to the flu shot, noting that something different had occurred with the last dose, leading to prolonged burning and pain that had fluctuated over time. She had suspected that the shot had been injected into her muscles, as the symptoms had varied based on her movements, particularly since the injection had been administered in her right arm, and she was right-handed. She had expressed dissatisfaction with her primary doctor and had reiterated that her allergy doctor had advised her to exercise extreme caution when taking medications, as she had experienced severe reactions in the past. She had recalled an incident from years ago in which she had taken a single pill of Maxide, passed out, hit her head on the concrete kitchen floor, and sustained a brain concussion, which had required hospitalization for a week. She had emphasized that her situation at the time of reporting had not been life-threatening but had sought clarification regarding whether the reaction had been caused by the shot being injected into a muscle. She had also questioned whether the dosage had been too high for her body weight and had requested recommendations related to that concern.  She had asked whether, given that the normal adult dosage might have been too high for her body weight, she could have received a pediatric dosage. She had explained that, upon discussing this with her allergy doctor, she had attempted to find a provider willing to administer a pediatric dose. However, she had been informed that it was against medical protocols, and her request had been denied. She had inquired whether she had been due for another booster shot.She had asked about the CDC's recommendations for people aged 65 and older regarding COVID-19 boosters. She had admitted that she had not recently checked the CDC's website for updated guidance. She had questioned how long the effects of her previous dose had been expected to last and when she should seek another booster shot. She had also wondered when the appropriate time would be to request a titer test to measure her antibody levels. She had sought information on whether massaging the area where she had received the injection could improve circulation or alleviate the symptoms. She had speculated that the vaccine might have remained in the muscle instead of circulating properly. She had wondered whether a massage therapist could help and whether such a treatment would be beneficial. She had asked whether a pharmacist could examine available reference materials to check the ingredients in the Pfizer and Moderna vaccines. She had specifically wanted to determine whether the fillers used in both vaccines had been the same, as she had suspected that she had been allergic to one of those components. She had explained that she had only begun experiencing muscle-related reactions after taking an antibiotic, and she had believed that her allergic response to the antibiotic had triggered a resurgence of symptoms related to the COVID-19 vaccines. She had then asked whether she should receive another COVID-19 shot. She had asked for an estimation of whether the likelihood had been high that the dosage had been injected into the muscle and whether that could have explained her reaction. She had also mentioned that her allergy doctor had recommended that she receive another shot, though she had expressed uncertainty about proceeding with it. She had hesitated about paying for another shot and had considered consulting her primary doctor. However, she had been contemplating changing primary doctors due to dissatisfaction with her previous provider's attitude. She had restated that her allergy doctor had encouraged her to get another vaccine, as her last dose had been administered in late September or early October of 2024, and she had questioned whether she had been due for another booster. The reporter had then remarked that if she had already developed sufficient antibodies, she might not have needed another shot. She had also acknowledged her ongoing pain and had planned to undergo physical therapy to address it. She had reflected on the challenges she had faced in distinguishing allergic reactions from normal vaccine side effects due to her extensive history of allergies.  The patient did not experience any additional symptoms or events.   No treatment medications were reported   This case was linked to MOD-2025-785740 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 28-Apr-2025: Live follow-up received contains non-significant information and reference ID added On 28-Apr-2025: Live follow-up received contains non-significant information and reference ID added On 29-Apr-2025: Live follow-up received contains non-significant information and reference ID added