COVID-19; interchange of vaccine products; This spontaneous case was reported by a patient and describes the occurrence of COVID-19 (COVID-19) and INTERCHANGE OF VACCINE PRODUCTS (interchange of vaccine products) in a 37-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     Previously administered products included for Product used for unknown indication: Pfizer / BioNTech (It was reported, Dose Number 1, Batch/Lot no. was Unknown. Injection site location was Left arm and Vaccine Administration Time at 02:00 PM) on 01-Mar-2021, Pfizer / BioNTech (It was reported, Dose Number 2, Batch/Lot no. was Unknown. Injection site location was Left arm and Vaccine Administration Time at 01:00 PM) on 01-Apr-2021, Pfizer / BioNTech (It was reported, Dose Number 3 and Batch/Lot no. was Unknown. Injection site location was Left arm and Vaccine Administration Time at 02:00 PM) on 06-Sep-2021; for Drug use for unknown indication: PENICILLIN [PENICILLIN NOS]. Past adverse reactions to the above products included Allergy with PENICILLIN [PENICILLIN NOS]; and No adverse event with Pfizer / BioNTech, Pfizer / BioNTech and Pfizer / BioNTech. Concurrent medical conditions included Immunoglobulin A decreased.    On 28-Apr-2022 at 9:00 AM, the patient received fourth dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced COVID-19 (COVID-19) and INTERCHANGE OF VACCINE PRODUCTS (interchange of vaccine products). At the time of the report, COVID-19 (COVID-19) had resolved and INTERCHANGE OF VACCINE PRODUCTS (interchange of vaccine products) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 19-May-2022, SARS-CoV-2 test: positive (Positive) Patient began testing positive again. On an unknown date, SARS-CoV-2 test: negative (Negative) Tested negative.         No concomitant medications were reported. The patient received Pfizer drug as treatment drug for COVID-19  It was reported patient was recovered and tested negative with minor ongoing symptoms. After several days, on day 9 of start of symptoms, symptoms returned, and patient began tested positive again. Patient was on day 18 of isolation. Doctor was unsure of rebound and considered it a severe case based on symptoms of continuing. Patient was asked to isolate for 21 days instead of the original 5/10.  Patient received unspecified Pfizer medication for COVID-19 treatment (first episode) and did not received any treatment for second episode.  Device date was reported as 28-May-2022.  Company comment-This spontaneous case concerns a female patient aged 37 years with no relevant medical history reported, who experienced the unexpected non serious AESI of COVID-19 on an unknown date after receiving the 4th dose of mRNA-1273 vaccine in the COVID-19 vaccination series. It was reported that the patient was treated for COVID infection with Pfizer drug from 11th May 2022 to 16th May 2022 for 6 days. Patient recovered with negative COVID test and minor symptoms. After several days symptoms recurred with a positive COVID test and was advised isolation. Patient has received initial schedule of vaccinations (dose 1,2 and 3) with TOZINAMERAN (interchange of vaccine products) noted. The current pandemic situation of COVID 19 may remain as confounder. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. Event seriousness assessed per medical judgement.; Sender's Comments: This spontaneous case concerns a female patient aged 37 years with no relevant medical history reported, who experienced the unexpected non serious AESI of COVID -19 on an unknown date after receiving the 4th dose of mRNA-1273 vaccine in the COVID -19 vaccination series. It was reported that the patient was treated for COVID infection with Pfizer drug from 11th May 2022 to 16th May 2022 for 6 days. Patient recovered with negative COVID test and minor symptoms. After several days symptoms recurred with a positive COVID test and was advised isolation. Patient has received initial schedule of vaccinations (dose 1,2 and 3) with TOZINAMERAN (interchange of vaccine products) noted. The current pandemic situation of COVID -19 may remain as confounder. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. Event seriousness assessed per medical judgement.