This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP) from medical information team, Program ID: (159558). The reporter is the patient. A 91-year-old female patient received BNT162b2 (COMIRNATY), as dose 3 (booster), single (Batch/Lot number: unknown) at the age of 91 years for covid-19 immunisation; coviD-19 vaccine mrna (mrna 1273) (MODERNA COVID-19 VACCINE), on 11Nov2021 as dose 4 (booster), single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history and concomitant medications were not reported. Vaccination history included: Pfizer Biontech covid-19 vaccine (DOSE 1, SINGLE), for Covid-19 immunization; Pfizer Biontech covid-19 vaccine (DOSE 2, SINGLE), for Covid-19 immunization. The following information was reported: INTERCHANGE OF VACCINE PRODUCTS (non-serious) with onset 11Nov2021, outcome "unknown", described as "received 3 doses of Pfizer covid-19 vaccine and was transferred to rehab and was inadvertently given MODERNA"; DIZZINESS (non-serious), FATIGUE (non-serious), outcome "unknown" and all described as "dizziness and tiredness". Additional Information: It was reported that caller was non-hcp calling on behalf of her mother, who already received 3 doses of Pfizer covid-19 vaccine and was transferred to rehab and was inadvertently given MODERNA 11Nov, 3 weeks after getting the 3rd dose of Pfizer covid booster dose. Caller reported that her mother experienced dizziness and tiredness. Caller asked what was the protocol or repercussion for those who received both or either-or different mRNA covid vaccine that was close together did it cause side effects or negative effects. Caller said that it did not matter of whose shot it was. Caller also stated, just say it was a Pfizer. In response to the queries, it was referred to the caller to manufacturer of MODERNA and caller was referred to CDC for protocols of covid vaccine. The response was received as : Gray Cap PI LAB-1485-9.0, A second booster dose of the Pfizer-BioNTech COVID-19 Vaccine (0.3 mL) may be administered to individuals 50 years of age and older at least 4 months after receipt of a first booster dose. Explained to the caller that this information was applicable from pfizer vaccine only. No specific information about double dosing. Another query from caller that, caller asked if she should wait for the new vaccine for her 4th booster (probably she's referring to her 2nd dose of booster/4th dose of pfizer covid vaccine). In response to the query the caller was referred to HCP. Also, Caller asked if it is true that we're studying about the new vaccine that would cover the B5 and B4. In response to that Referred the caller to pfizer website for more information. Another question from the caller that, this sound passing the box, your company should know whether or not double dosing your own product, they were just the same vaccine but a little bit stronger, your company should know the side effects of your medication to able to guide the CDC, if you don't know what your drugs would gonna do to the people this is a bad thing, big pharma. Caller added, maybe they should study that, referring to double dosing of Pfizer covid-19 vaccine, let's get everyone to be the guinea pig, and would take the drug off the market when someone died, that's what they did with caller father with (withheld) (unverified, sounds like). Caller also reported that she took some medications that was take off from the market and thanked did not die taking of those, It should be tested. (unverified products).  The information on the batch/lot number for BNT162b2 has been requested and will be submitted if and when received.