Chest tightness; Headache; Tired; Little spacy; Received Moderna COVID-19 vaccine and then received the first dose of Pfizer COVID-19; This is a spontaneous report from a contactable consumer (patient). A 56-year-old female patient received BNT162B2 (PFIZER-BIONTECH COVID-19 VACCINE; Lot Number was not reported), via an unspecified route of administration, on 21Jul2021 (at the age of 56 years), as dose 2 (initial Pfizer dose), single, for COVID-19 immunization; and COVID-19 vaccine mRNA (mRNA 1273) (MODERNA COVID-19 VACCINE; Lot Number was not reported), via an unspecified route of administration, on 19Jan2021, as an unspecified dose and frequency, for COVID-19 immunization. The patient's medical history included childbirth, broken bones, and surgeries. The patient's concomitant medication included estradiol (ESTROGEN Patch). The patient was not obese and had no underlying health conditions but had an assortment of painful experiences throughout life. The patient received MODERNA COVID-19 vaccine on 19Jan2021 and then received the first dose of Pfizer COVID-19 vaccine yesterday (21Jul2021). The patient had an extremely horrific reaction to MODERNA vaccine (as reported). She received product and commented that "it was great" (as reported) as she had an adverse event including felt like she was going to die, horrific experience. The patient had antibodies from MODERNA vaccine, no T cells (2021). Around the time the patient was vaccinated with MODERNA vaccine (19Jan2021), they sent seven people to the hospital and someone died in a city; same time as recalled in withheld doses. According to the patient, whether it was her body or reconstituted, something was absolutely wrong with that dose (sister indicated fourteen people hospitalized and one deceased). After the MODERNA vaccine, the patient's liver hurts and teeth were throbbing lasting 4 to 5 days. The patient was so sick, had pretty healthy lifestyle, and not obese. The patient literally thought she was going to go to the emergency room (ER). Someone died that day. Would have gotten 3 weeks, the patient was so incredibly sick from MODERNA vaccine. On 21Jul2021 (this week), the patient started with Pfizer vaccine without antibodies and T-cells testing. The patient received first dose of Pfizer product yesterday (21Jul2021) and did experience chest tightness in which she took a diphenhydramine hydrochloride (BENADRYL); did it in the morning. They lowered her estrogen patch and maintained hydration as estrogen can cause inflammation. With the Pfizer vaccine, the patient had headache, tired, and a little spacy on 21Jul2021. Fine by the next day (22Jul2021). They were not going to do a tissue sample, clean slate. The patient asked the following questions including if a person could take into too much mRNA; if she should do another Pfizer vaccine administration and if this would be a third shot; if they would test T cells and antibodies (boss is an immunologist); if the booster is going to be the same thing; if there is any information on interchangeability of product; if the Pfizer-BioNTech COVID-19 vaccine the same vaccine in different countries; if Pfizer has provided a statement on the need for a booster dose (third dose); and if Pfizer is investigating the need for a booster dose (talking about a third dose or a different formulation especially in those immunocompromised). The patient recovered from the events on 22Jul2021.  The lot number for the vaccine, BNT162B2, was not provided and will be requested during follow up.